Dr Tim Brookes

Research Interests

Tim's research activities are on the engineering side of psychoacoustics: measuring, modelling and exploiting the relationships between the physical characteristics of sound and the corresponding perception evoked in listeners. He is particularly interested in the development of systems to predict and/or optimise the perceived quality of audio.

Postgraduate and funded projects supervised and managed include:

Teaching

Tim's teaching focuses on acoustics and psychoacoustics (as well as employment preparation, as part of his role as Assistant Senior Professional Training Tutor). He currently teaches the following modules:

  • TON1021 Acoustics & Computer Audio Systems A
  • TON1022 Acoustics & Computer Audio Systems B
  • TONP014 Personal & Professional Development
  • TONP015 Evaluation of Placement Learning
  • TONP016 Transfer of Placement Learning
  • TON3014 Technical Project

Contact Me

E-mail:
Phone: 01483 68 6539

Find me on campus
Room: 06 BC 03

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Publications

Journal articles

  • Francombe J, Brookes T, Mason R. (2017) 'Evaluation of Spatial Audio Reproduction Methods (Part 1): Elicitation of Perceptual Differences'. Audio Engineering Society Journal of the Audio Engineering Society, 65 (3), pp. 198-211.

    Abstract

    There are a wide variety of spatial audio reproduction systems available, from a single loudspeaker to many spatially distributed loudspeakers. An important factor in the selection, development, or optimization of such systems is listener preference, and the important perceptual characteristics that contribute to this. An experiment was performed to determine the attributes that contribute to listener preference for a range of spatial audio reproduction methods. Experienced and inexperienced listeners made preference ratings for combinations of seven program items replayed over eight reproduction systems, and reported the reasons for their judgments. Automatic text clustering reduced redundancy in the responses by approximately 90%, facilitating subsequent group discussions that produced clear attribute labels, descriptions, and scale end-points. Twenty-seven and twenty-four attributes contributed to preference for the experienced and inexperienced listeners respectively. The two sets of attributes contain a degree of overlap (ten attributes from the two sets were closely related); however, the experienced listeners used more technical terms whilst the inexperienced listeners used more broad descriptive categories.

  • Francombe J, Brookes T, Mason R, Woodcock J. (2017) 'Evaluation of Spatial Audio Reproduction Methods (Part 2): Analysis of Listener Preference'. Audio Engineering Society Journal of the Audio Engineering Society, 65 (3), pp. 212-225.

    Abstract

    It is desirable to determine which of the many different spatial audio reproduction systems listeners prefer, and the perceptual attributes that are most important to listener experience, so that future systems can be perceptually optimized. A paired comparison preference rating experiment was performed alongside a free elicitation task for eight reproduction methods (consumer and professional systems with a wide range of expected quality) and seven program items (representative of potential broadcast material). The experiment was performed by groups of experienced and inexperienced listeners. Thurstone Case V modeling was used to produce preference scales. Both listener groups preferred systems with increased spatial content; nineand five-channel systems were most preferred. The use of elicited attributes was analyzed alongside the preference ratings, resulting in an approximate hierarchy of attribute importance: three attributes (amount of distortion, output quality, and bandwidth) were found to be important for differentiating systems where there was a large preference difference; sixteen were always important (most notably enveloping and horizontal width); and seven were used alongside small preference differences.

  • Pearce A, Brookes T, Dewhirst M, Mason R. (2016) 'Eliciting the most prominent perceived differences between microphones'. ACOUSTICAL SOC AMER AMER INST PHYSICS JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 139 (5), pp. 2970-2981.
  • Conetta R, Brookes T, Rumsey F, ZielińSki S, Dewhirst M, Jackson P, Bech S, Meares D, George S. (2015) 'Spatial audio quality perception (Part 1): Impact of commonly encountered processes'. AES: Journal of the Audio Engineering Society, 62 (12), pp. 831-846.

    Abstract

    Spatial audio processes (SAPs) commonly encountered in consumer audio reproduction systems are known to generate a range of impairments to spatial quality. Two listening tests (involving two listening positions, six 5-channel audio recordings, and 48 SAPs) indicate that the degree of quality degradation is determined largely by the nature of the SAP but that the effect of a particular SAP can depend on program material and on listening position. Combining off-center listening with another SAP can reduce spatial quality significantly compared to auditioning that SAP centrally. These findings, and the associated listening test data, can guide the development of an artificial-listener-based spatial audio quality evaluation system.

  • Conetta R, Brookes T, Rumsey F, ZielińSki S, Dewhirst M, Jackson P, Bech S, Meares D, George S. (2015) 'Spatial audio quality perception (Part 2): A linear regression model'. AES: Journal of the Audio Engineering Society, 62 (12), pp. 847-860.

    Abstract

    Previously-obtained data, quantifying the degree of quality degradation resulting from a range of spatial audio processes (SAPs), can be used to build a regression model of perceived spatial audio quality in terms of previously developed spatially and timbrally relevant metrics. A generalizable model thus built, employing just five metrics and two principal components, performs well in its prediction of the quality of a range of program types degraded by a multitude of SAPs commonly encountered in consumer audio reproduction, auditioned at both central and off-center listening positions. Such a model can provide a correlation to listening test data of r = 0.89, with a root mean square error (RMSE) of 11%, making its performance comparable to that of previous audio quality models and making it a suitable core for an artificial-listener-based spatial audio quality evaluation system.

  • Ashby T, Brookes T, Mason R. (2014) 'Towards a head-movement-aware spatial localisation model: Elevation'. 21st International Congress on Sound and Vibration 2014, ICSV 2014, 4, pp. 2808-2815.

    Abstract

    Copyright © (2014) by the International Institute of Acoustics & Vibration All rights reserved.A multiple-microphone-sphere-based localisation model has been developed that predicts source location by modelling the cues given by head movement. In order to inform improvements to this model, a series of experiments was devised to investigate the impact of head movement cues on the localisation response accuracy of human listeners. It was shown that head movements improve elevation localisation response accuracy for noise sources. When pinna cues are impaired the significance of head movement cues increases. The improved localisation resulting from head movement is due to dynamic cues available during the period of movement, and not to improved static cues available once the head is turned to face the sound source. Head movements improve elevation localisation to a similar degree for band- limited sources with differing centre frequencies (500 Hz, 2 kHz and 6 kHz), which indicates that both dynamic ILDs and dynamic ITDs are used. Head movements do not improve elevation response accuracy for programme items with less than an octave bandwidth. Head movements improve elevation response accuracy to a greater degree for sources further away from the equatorial plane.

  • Hummersone C, Mason RD, Brookes TS. (2013) 'A Comparison of Computational Precedence Models for Source Separation in Reverberant Environments'. Journal of the Audio Engineering Society, 61 (7/8 (July/August)), pp. 508-520.

    Abstract

    Reverberation is a problem for source separation algorithms. Because the precedence effect allows human listeners to suppress the perception of reflections arising from room boundaries, numerous computational models have incorporated the precedence effect. However, relatively little work has been done on using the precedence effect in source separation algorithms. This paper compares several precedence models and their influence on the performance of a baseline separation algorithm. The models were tested in a variety of reverberant rooms and with a range of mixing parameters. Although there was a large difference in performance among the models, the one that was based on interaural coherence and onset-based inhibition produced the greatest performance improvement. There is a trade-off between selecting reliable cues that correspond closely to free-field conditions and maximizing the proportion of the input signals that contributes to localization. For optimal source separation performance, it is necessary to adapt the dynamic component of the precedence model to the acoustic conditions of the room.

  • Kim C, Mason R, Brookes TS. (2013) 'Head movements made by listeners in experimental and real-life listening activities'. Journal of the Audio Engineering Society, 61 (6 (June)), pp. 425-438.
  • Hummersone C, Mason R, Brookes T. (2011) 'Ideal Binary Mask Ratio: a novel metric for assessing binary-mask-based sound source separation algorithms'. IEEE IEEE Transactions on Audio, Speech and Language Processing, 19 (7), pp. 2039-2045.

    Abstract

    A number of metrics has been proposed in the literature to assess sound source separation algorithms. The addition of convolutional distortion raises further questions about the assessment of source separation algorithms in reverberant conditions as reverberation is shown to undermine the optimality of the ideal binary mask (IBM) in terms of signal-to-noise ratio (SNR). Furthermore, with a range of mixture parameters common across numerous acoustic conditions, SNR–based metrics demonstrate an inconsistency that can only be attributed to the convolutional distortion. This suggests the necessity for an alternate metric in the presence of convolutional distortion, such as reverberation. Consequently, a novel metric—dubbed the IBM ratio (IBMR)—is proposed for assessing source separation algorithms that aim to calculate the IBM. The metric is robust to many of the effects of convolutional distortion on the output of the system and may provide a more representative insight into the performance of a given algorithm.

  • Kim C, Mason RD, Brookes T. (2011) 'Head-movement-aware signal capture for evaluation of spatial acoustics'. Multi Science Publishing Building Acoustics, 18 (1), pp. 207-226.

    Abstract

    This research incorporates the nature of head movement made in listening activities, into the development of a quasi- binaural acoustical measurement technique for the evaluation of spatial impression. A listening test was conducted where head movements were tracked whilst the subjects rated the perceived source width, envelopment, source direction and timbre of a number of stimuli. It was found that the extent of head movements was larger when evaluating source width and envelopment than when evaluating source direction and timbre. It was also found that the locus of ear positions corresponding to these head movements formed a bounded sloped path, higher towards the rear and lower towards the front. This led to the concept of a signal capture device comprising a torso-mounted sphere with multiple microphones. A prototype was constructed and used to measure three binaural parameters related to perceived spatial impression - interaural time and level differences (ITD and ILD) and interaural cross- correlation coefficient (IACC). Comparison of the prototype measurements to those made with a rotating Head and Torso Simulator (HATS) showed that the prototype could be perceptually accurate for the prediction of source direction using ITD and ILD, and for the prediction of perceived spatial impression using IACC. Further investigation into parameter derivation and interpolation methods indicated that 21 pairs of discretely spaced microphones were sufficient to measure the three binaural parameters across the sloped range of ear positions identified in the listening test.

  • Hummersone C, Mason R, Brookes T. (2010) 'Dynamic precedence effect modeling for source separation in reverberant environments'. IEEE Transactions on Audio, Speech and Language Processing, 18 (7), pp. 1867-1871.
  • Neher T, Brookes T, Mason R. (2006) 'Musically Representative Signals for Use in Interaural Cross-Correlation Coefficient Measurements'. Acta Acustica United with Acustica, 92 (5), pp. 787-796.
  • Supper B, Brookes T, Rumsey F. (2006) 'An auditory onset detection algorithm for improved automatic source localization'. IEEE Transactions on Audio, Speech and Language Processing, 14 (3), pp. 1008-1017.
  • Neher T, Brookes T, Rumsey F. (2006) 'A Hybrid Technique for Validating Unidimensionality of Perceptual Variation in a Spatial Auditory Stimulus Set'. Journal of the Audio Engineering Society, 54 (4), pp. 259-275.
  • Mason R, Brookes T, Rumsey F. (2005) 'Frequency dependency of the relationship between perceived auditory source width and the interaural cross-correlation coefficient for time-invariant stimuli.'. J Acoust Soc Am, United States: 117 (3 Pt 1), pp. 1337-1350.
  • Mason R, Brookes T, Rumsey F. (2005) 'The effect of various source signal properties on measurements of the interaural cross-correlation coefficient'. Acoustical Society of Japan Acoustical Science and Technology, 26 (2), pp. 102-113.
  • Brookes T, Tyrrell A, Howard D. (2000) 'On the differences between conventional and auditory spectrograms of English consonants'. Logopedics Phoniatrics Vocology, 25 (2), pp. 72-79.
  • Tyrrell AM, Howard DM, Brookes T. (1998) 'Transputer-based human hearing simulation'. Simulation Practice and Theory, 6 (5), pp. 479-491.
  • Howard DM, Hirson A, Brookes TS, Tyrrell AM. (1995) 'Spectrography of Disputed Speech Samples by Peripheral Human Hearing Modelling'. Forensic Linguistics, 2 (1), pp. 22-38.

Conference papers

  • Hermes K, Brookes TS, Hummersone C. (2016) 'The harmonic centroid as a predictor of string instrument timbral clarity'. Audio Engineering Society Audio Engineering Society proceedings, Paris, France: 140th Convention of Audio Engineering Society
  • Font F, Brookes TS, Fazekas G, Guerber M, La Burthe A, Plans D, Plumbley M, Shaashua M, Wang W, Serra X. (2016) 'Audio Commons: bringing Creative Commons audio content to the creative industries'. London, UK: 61st International Conference: Audio for Games

    Abstract

    Significant amounts of user-generated audio content, such as sound effects, musical samples and music pieces, are uploaded to online repositories and made available under open licenses. Moreover, a constantly increasing amount of multimedia content, originally released with traditional licenses, is becoming public domain as its license expires. Nevertheless, the creative industries are not yet using much of all this content in their media productions. There is still a lack of familiarity and understanding of the legal context of all this open content, but there are also problems related with its accessibility. A big percentage of this content remains unreachable either because it is not published online or because it is not well organised and annotated. In this paper we present the Audio Commons Initiative, which is aimed at promoting the use of open audio content and at developing technologies with which to support the ecosystem composed by content repositories, production tools and users. These technologies should enable the reuse of this audio material, facilitating its integration in the production workflows used by the creative industries. This is a position paper in which we describe the core ideas behind this initiative and outline the ways in which we plan to address the challenges it poses.

  • Pearce A, Brookes TS, Mason R, Dewhirst M. (2016) 'Measurements to determine the ranking accuracy of perceptual models'. Audio Engineering Society Paris, France: 140th Convention of the Audio Engineering Society
    [ Status: Accepted ]
  • Francombe J, Brookes T, Mason R, Woodcock J. (2016) 'Determining and Labeling the Preference Dimensions of Spatial Audio Replay'. IEEE Lisbon, Portugal: QoMEX 2016
    [ Status: Accepted ]

    Abstract

    There are many spatial audio reproduction systems currently in domestic use (e.g. mono, stereo, surround sound, sound bars, and headphones). In an experiment, pairwise pref-erence magnitude ratings for a range of such systems were collected from trained and untrained listeners. The ratings were analysed using internal preference mapping to: (i) uncover the principal perceptual dimensions of listener preference; (ii) label the dimensions based on the important perceptual attributes; and (iii) observe differences between trained and untrained listeners. To aid with labelling the dimensions, perceptual attributes were elicited alongside the preference ratings and were analysed by: (i) considering a metric derived from the frequency of use of each attribute and the magnitude of the related preference judgements; and (ii) observing attribute use for comparisons between specific methods. The first preference dimension accounted for the vast majority of the variance in ratings; it was related to multiple important attributes, including those associated with spatial capability and freedom from distortion. All participants exhibited a preference for reproduction methods that were positively correlated with the first dimension (most notably 5-, 9-, and 22-channel surround sound). The second dimension accounted for only a very small proportion of the variance, and appeared to separate the headphone method from the other methods. The trained and untrained listeners generally showed opposite preferences in the second dimension, suggesting that trained listeners have a higher preference for headphone reproduction than untrained listeners.

  • Hermes K, Brookes TS, Hummersone C. (2015) 'The influence of dumping bias on timbral clarity ratings'. Audio Engineering Society 139th International AES Convention papers, New York, USA: 139th International AES Convention

    Abstract

    When listening test subjects are required to rate changes in a single attribute, but also hear changes in other attributes, their ratings can become skewed by “dumping bias.” To assess the influence of dumping bias on timbral “clarity” ratings, listeners were asked to rate stimuli: (i) in terms of clarity only; and (ii) in terms of clarity, warmth, fullness, and brightness. Clarity ratings of type (i) showed (up to 20%) larger interquartile ranges than those of type (ii). It is concluded that in single-attribute timbral rating experiments, statistical noise—potentially resulting from dumping bias—can be reduced by allowing listeners to rate additional attributes either simultaneously or beforehand.

  • Francombe J, Brookes TS, Mason R, Melchior F. (2015) 'Loudness matching multichannel audio programme material with listeners and predictive models'. 139th International AES Convention papers, New York, USA: 139th International AES Convention

    Abstract

    Loudness measurements are often necessary in psychoacoustic research and legally required in broadcasting. However, existing loudness models have not been widely tested with new multichannel audio systems. A trained listening panel used the method of adjustment to balance the loudnesses of eight reproduction methods: low-quality mono, mono, stereo, 5-channel, 9-channel, 22-channel, ambisonic cuboid, and headphones. Seven programme items were used, including music, sport, and a lm soundtrack. The results were used to test loudness models including simple energy-based metrics, variants of ITU-R BS.1770, and complex psychoacoustically motivated models. The mean differences between the perceptual results and model predictions were statistically insignificant for all but the simplest model. However, some weaknesses in the model predictions were highlighted.

  • Pearce A, Brookes TS, Dewhirst M. (2015) 'Validation of Experimental Methods to Record Stimuli for Microphone Comparisons'. Audio Engineering Society 139th International AES Convention papers, New York, USA: 139th International AES Convention

    Abstract

    Test recordings can facilitate evaluation of a microphone's characteristics but there is currently no standard or experimentally validated method for making recordings to compare the perceptual characteristics of microphones. This paper evaluates previously used recording methods, concluding that, of these, the most appropriate approach is to record multiple microphones simultaneously. However, perceived differences between recordings made with microphones in a multi-microphone array might be due to (i) the characteristics of the microphones and/or (ii) the different locations of the microphones. Listening tests determined the maximum acceptable size of a multi-microphone array to be 150 mm in diameter, but the diameter must be reduced to no more than 100 mm if the microphones to be compared are perceptually very similar.

  • Francombe J, Brookes T, Mason RD. (2015) 'Perceptual evaluation of spatial quality: where next?'. Florence: 22nd International Congress on Sound and Vibration

    Abstract

    From the early days of reproduced sound, engineers have sought to reproduce the spatial properties of sound fields, leading to the development of a range of technologies. Two-channel stereo has been prevalent for many years; however, systems with a higher number of discrete channels (including rear and height loudspeakers) are becoming more common and, recently, there has been a move towards loudspeaker-agnostic methods using audio objects. Perceptual evaluation, and perceptually-informed objective measurement, of alternative reproduction systems can inform further development and steer future innovations. It is important, therefore, that any gaps in the field of perceptual evaluation and measurement are identified and that future work aims to fill those gaps. A standard research paradigm in the field is identification of the perceptual attributes of a stimulus set, facilitating controlled listening tests and leading to the development of predictive models. There have been numerous studies that aim to discover the perceptual attributes of reproduced spatial sound, leading to more than fifty descriptive terms. However, a literature review revealed the following key problems: (i) there is little agreement on exact definitions, nor on the relative importance of each attribute; (ii) there may be important attributes that have not yet been identified (e.g. attributes arising from differences between real and reproduced audio, or pertaining to new 3D or object-based methods); and (iii) there is no model of overall spatial quality based directly on the important attributes. Consequently, the authors contend that future research should focus on: (i) ascertaining which attributes of reproduced spatial audio are most important to listeners; (ii) identifying any important attributes currently missing; (iii) determining the relationships between the important attributes and listener preference; (iv) modelling overall spatial quality in terms of the important perceptual attributes; and (v) modelling these perceptual attributes in terms of their physical correlates.

  • Francombe J, Brookes T, Mason RD. (2015) 'Elicitation of the differences between real and reproduced audio'. Audio Engineering Society Preprint, Warsaw: 138th Audio Engineering Society Convention 9307

    Abstract

    To improve the experience of listening to reproduced audio, it is beneficial to determine the differences between listening to a live performance and a recording. An experiment was performed in which three live performances (a jazz duet, a jazz-rock quintet, and a brass quintet) were captured and simultaneously replayed over a nine-channel with-height surround sound system. Experienced and inexperienced listeners moved freely between the live performance and the reproduction and described the difference in listening experience. In subsequent group discussions, the experienced listeners produced twenty-nine categories using some terms that are not commonly found in the current spatial audio literature. The inexperienced listeners produced five categories that overlapped with the experienced group terms but that were not as detailed.

  • Francombe J, Brookes T, Mason R, Flindt R, Coleman P, Liu Q, Jackson PJB. (2015) 'Production and reproduction of programme material for a variety of spatial audio formats'. Proc. AES 138th Int. Conv. (e-Brief), Warsaw, Warsaw: 138th Audio Engineering Society Convention, pp. 4-4.

    Abstract

    For subjective experimentation on 3D audio systems, suitable programme material is needed. A large-scale recording session was performed in which four ensembles were recorded with a range of existing microphone techniques (aimed at mono, stereo, 5.0, 9.0, 22.0, ambisonic, and headphone reproduction) and a novel 48-channel circular microphone array. Further material was produced by remixing and augmenting pre-existing multichannel content. To mix and monitor the programme items (which included classical, jazz, pop and experimental music, and excerpts from a sports broadcast and a lm soundtrack), a flexible 3D audio reproduction environment was created. Solutions to the following challenges were found: level calibration for different reproduction formats; bass management; and adaptable signal routing from different software and fille formats.

  • Pike C, Mason RD, Brookes T. (2014) 'Auditory compensation for spectral coloration'. Audio Engineering Society Preprint, New York: 137th Audio Engineering Society Convention 9138

    Abstract

    The “spectral compensation effect” (Watkins, 1991) describes a decrease in perceptual sensitivity to spectral modifications caused by the transmission channel (e.g., loudspeakers, listening rooms). Few studies have examined this effect: its extent and perceptual mechanisms are not confirmed. The extent to which compensation affects the perception of sounds colored by loudspeakers and other channels should be determined. This compensation has been mainly studied with speech. Evidence suggests that speech engages special perceptual mechanisms, so compensation might not occur with non-speech sounds. The current study provides evidence of compensation for spectrum in nonspeech tests: channel coloration was reduced by approximately 20%.

  • Stokes T, Hummersone C, Brookes T, Mason A. (2014) 'Perceptual quality of audio separated using sigmoidal masks'. 137th Audio Engineering Society Convention 2014, , pp. 167-173.

    Abstract

    Separation of underdetermined audio mixtures is often performed in the Time-Frequency (TF) domain by masking each TF element according to its target-to-mixture ratio. This work uses sigmoidal functions to map the target-to-mixture ratio to mask values. The series of functions used encompasses the ratio mask and an approximation of the binary mask. Mixtures are chosen to represent a range of different amounts of TF overlap, then separated and evaluated using objective measures. PEASS results show improved interferer suppression and artifact scores can be achieved using softer masking than that applied by binary or ratio masks. The improvement in these scores gives an improved overall perceptual score; this observation is repeated at multiple TF resolutions.

  • Ashby T, Mason RD, Brookes T. (2014) 'Elevation localisation response accuracy on vertical planes of differing azimuth'. Audio Engineering Society Preprint, Berlin, Germany: 136th Audio Engineering Society Convention 9046

    Abstract

    Head movement has been shown to significantly improve localisation response accuracy in elevation. It is unclear from previous research whether this is due to static cues created once the head has reached a new stationary position or dynamic cues created through the act of moving the head. In this experiment listeners were asked to report the location of loudspeakers placed on vertical planes at four different azimuth angles (0°, 36°, 72°, 108°) with no head movement. Static elevation response accuracy was significantly more accurate for sources away from the median plane. This finding, combined with the statement that listeners orient to face the source when localising, suggests that dynamic cues are the cause of improved localisation through head movement.

  • Pike C, Mason RD, Brookes T. (2014) 'The effect of auditory memory on the perception of timbre'. Audio Engineering Society Preprint, Berlin: 136th Audio Engineering Society Convention 9028

    Abstract

    Listeners are more sensitive to timbral differences when comparing stimuli side-by-side than temporally-separated. The contributions of auditory memory and spectral compensation to this effect are unclear. A listening test examined the role of auditory memory in timbral discrimination, across retention intervals (RIs) of up to 40 s. For timbrally complex music stimuli discrimination accuracy was good across all RIs, but there was increased sensitivity to onset spectrum, which decreased with increasing RI. Noise stimuli showed no onset sensitivity but discrimination performance declined with RIs of 40 s. The difference between program types may suggest different onset sensitivity and memory encoding (categorical vs non-categorical). The onset bias suggests that memory effects should be measured prior to future investigation of spectral compensation.

  • Stokes T, Hummersone C, Brookes TS. (2013) 'Reducing Binary Masking Artefacts in Blind Audio Source Separation'. Audio Engineering Society Proceedings of the 134th Audio Engineering Society Convention, Rome, Italy: 134th Audio Engineering Society Convention paper 8853

    Abstract

    Binary masking is a common technique for separating target audio from an interferer. Its use is often justi ed by the high signal-to-noise ratio achieved. The mask can introduce musical noise artefacts, limiting its perceptual performance and that of techniques that use it. Three mask-processing techniques, involving adding noise or cepstral smoothing, are tested and the processed masks are compared to the ideal binary mask using the perceptual evaluation for audio source separation (PEASS) toolkit. Each processing technique's parameters are optimised before the comparison is made. Each technique is found to improve the overall perceptual score of the separation. Results show a trade-o between interferer suppression and artefact reduction.

  • Pike C, Brookes T, Mason R. (2013) 'Auditory adaptation to loudspeaker and listening room acoustics'. 135th Audio Engineering Society Convention 2013, , pp. 116-125.

    Abstract

    Timbrai qualities of loudspeakers and rooms are often compared in listening tests involving short listening periods. Outside the laboratory, listening occurs over a longer time course. In a study by Olive et al. (1995) smaller timbrai differences between loudspeakers and between rooms were reported when comparisons were made over longer versus shorter time periods. This is a form of timbrai adaptation, a decrease in sensitivity to timbre over time. The current study confirms this adaptation and establishes that it is not due to response bias but may be due to timbrai memory, specific mechanisms compensating for transmission channel acoustics, or attentional factors. Modifications to listening tests may be required where tests need to be representative of listening outside of the laboratory.

  • Ashby T, Mason RD, Brookes T. (2013) 'Head movements in three-dimensional localisation'. Audio Engineering Society Preprint Proceedings of the 134th Audio Engineering Society Convention, Rome, Italy: 134th Audio Engineering Society Convention 8881

    Abstract

    Previous studies give contradicting evidence as to the importance of head movements in localisation. In this study head movements were shown to increase localisation response accuracy in elevation and azimuth. For elevation, it was found that head movement improved localisation accuracy in some cases and that when pinna cues were impeded the significance of head movement cues was increased. For azimuth localization, head movement reduced front-back confusions. There was also evidence that head movement can be used to enhance static cues for azimuth localisation. Finally, it appears that head movement can increase the accuracy of listeners’ responses by enabling an interaction between auditory and visual cues.

  • Stokes T, Brookes TS, Hummersone C. (2012) 'Improving the Quality of Separated Audio: What Works?'. Salford UK: 1st Anniversary Celebration for the BBC Audio Research Partnership
  • Ashby T, Mason R, Brookes T. (2011) 'Prediction of perceived elevation using multiple psuedo-binaural microphones'. London, UK : Audio Engineering Society Audio Engineering Society Preprint, London, UK: 130th Audio Engineering Society Convention

    Abstract

    Computational auditory models that predict the perceived location of sound sources in terms of azimuth are already available, yet little has been done to predict perceived elevation. Interaural time and level differences, the primary cues in horizontal localisation, do not resolve source elevation, resulting in the ‘Cone of Confusion’. In natural listening, listeners can make head movements to resolve such confusion. To mimic the dynamic cues provided by head movements, a multiple microphone sphere was created, and a hearing model was developed to predict source elevation from the signals captured by the sphere. The prototype sphere and hearing model proved effective in both horizontal and vertical localisation. The next stage of this research will be to rigorously test a more physiologically accurate capture device.

  • Hummersone C, Mason R, Brookes T. (2010) 'A comparison of computational precedence models for source separation in reverberant environments'. Audio Engineering Society Audio Engineering Society Preprint, London, UK: 128th Audio Engineering Society Convention 7981
  • Kim C, Mason R, Brookes T. (2010) 'Investigation into and modelling of head movement for objective evaluation of the spatial impression of audio'. Boston, USA : Acoustical Society of America Journal of the Acoustical Society of America, Baltimore, USA: 159th Meeting of the Acoustical Society of America 127 (3), pp. 1886-1886.
  • Williams D, Brookes T. (2010) 'Testing a prototype timbre morpher'. London: DMRN+4: Digital Music Research Network
  • Kim C, Mason R, Brookes T. (2010) 'Validation of a simple spherical head model as a signal capture device for head-movement-aware prediction of perceived spatial impression'. Audio Engineering Society Proceedings of the 40th International AES Conference, Tokyo, Japan: AES 40th International Conference (Spatial Audio: Sense the Sound of Space)

    Abstract

    In order to take head movement into account in objective evaluation of perceived spatial impression (including source direction), a suitable binaural capture device is required. A signal capture system was suggested that consisted of a head-sized sphere containing multiple pairs of microphones which, in comparison to a rotating head and torso simulator (HATS), has the potential for improved measurement speed and the capability to measure time varying systems, albeit at the expense of some accuracy. The error introduced by using a relatively simple sphere compared to a more physically accurate HATS was evaluated in terms of three binaural parameters related to perceived spatial impression – interaural time and level differences (ITD and ILD) and interaural cross-correlation coefficient (IACC). It was found that whilst the error in the IACC measurements was perceptually negligible when the sphere was mounted on a torso, the differences in measured ITD and ILD values between the sphere-with-torso and HATS were not perceptually negligible. However, it was found that the sphere-with-torso could give accurate predictions of source location based on ITD and ILD, through the use of a look-up table created from known ITD-ILD-direction mappings. Therefore the validity of the multi-microphone sphere-with-torso as a binaural signal capture device for perceptually relevant measurements of source direction (based on ITD and ILD) and spatial impression (based on IACC) was demonstrated.

  • Kim C, Mason R, Brookes T. (2010) 'Development of a head-movement-aware signal capture system for the prediction of acoustical spatial impression'. Sidney : International Congress of Acoustics (ICA) Proceedings of the 20th International Congress on Acoustics, Sydney, Australia: 20th International Congress on Acoustics 4, pp. 2768-2775.

    Abstract

    This research introduces a novel technique for capturing binaural signals for objective evaluation of spatial impression; the technique allows for simulation of the head movement that is typical in a range of listening activities. A subjective listening test showed that the amount of head movement made was larger when listeners were rating perceived source width and envelopment than when rating source direction and timbre, and that the locus of ear positions corresponding to the pattern of head movement formed a bounded sloped path – higher towards the rear and lower towards the front. Based on these findings, a signal capture system was designed comprising a sphere with multiple microphones, mounted on a torso. Evaluation of its performance showed that a perceptual model incorporating this capture system is capable of perceptually accurate prediction of source direction based on interaural time and level differences (ITD and ILD), and of spatial impression based on interaural cross-correlation coefficient (IACC). Investigation into appropriate parameter derivation and interpolation techniques determined that 21 pairs of spaced microphones were sufficient to measure ITD, ILD and IACC across the sloped range of ear positions.

  • Brookes T. (2010) 'Psychoacoustic Engineering at the Institute of Sound Recording'. Royal Academy of Engineering, London, UK: Audio Engineering Society British Section 'Cutting Edge Research' Lecture Series
  • Williams D, Brookes T. (2010) 'Perceptually-Motivated Audio Morphing: Warmth'. Audio Engineering Society Convention Proceedings, Paper 8019, London, UK: AES 128th Convention

    Abstract

    A system for morphing the warmth of a sound independently from its other timbral attributes was coded, building on previous work morphing brightness only (1), and morphing brightness and softness (2). The new warmth-softness-brightness morpher was perceptually validated using a series of listening tests. A Multidimensional Scaling analysis of listener responses to paired-comparisons showed perceptually orthogonal movement in two dimensions within a warmth-morphed and everything-else-morphed stimulus set. A verbal elicitation experiment showed that listeners’ descriptive labeling of these dimensions was as intended. A further ‘quality control’ experiment provided evidence that no ‘hidden’ timbral attributes were altered in parallel with the intended ones. A complete timbre morpher can now be considered for further work, and evaluated using the tri-stage procedure documented here.

  • Kim C, Mason R, Brookes T. (2010) 'A quasi-binaural approach to head-movement-aware evaluation of spatial acoustics'. Sidney : The International Congress on Acoustics (ICA) Proceedings of the International Symposium on Room Acoustics, Melbourne, Australia: International Symposium on Room Acoustics. A Satellite of the International Congress on Acoustics. General papers 4 (1), pp. 292-300.

    Abstract

    This research incorporates the nature of head movement made in listening activities, into the development of a quasibinaural acoustical measurement technique for the evaluation of spatial impression. A listening test was conducted where head movements were tracked whilst the subjects rated the perceived source width, envelopment, source direction and timbre of a number of stimuli. It was found that the extent of head movements was larger when evaluating source width and envelopment than when evaluating source direction and timbre. It was also found that the locus of ear positions corresponding to these head movements formed a bounded sloped path, higher towards the rear and lower towards the front. This led to the concept of a signal capture device comprising a torso-mounted sphere with multiple microphones. A prototype was constructed and used to measure three binaural parameters related to perceived spatial impression - interaural time and level differences (ITD and ILD) and interaural crosscorrelation coefficient (IACC). Comparison of the prototype measurements to those made with a rotating Head and Torso Simulator (HATS) showed that the prototype could be perceptually accurate for the prediction of source direction using ITD and ILD, and for the prediction of perceived spatial impression using IACC. Further investigation into parameter derivation and interpolation methods indicated that 21 pairs of discretely spaced microphones were sufficient to measure the three binaural parameters across the sloped range of ear positions identified in the listening test.

  • Mason R, Kim C, Brookes T. (2009) 'Perception of head-position-dependent variations in interaural cross-correlation coefficient'. Munich, Germany : Audio Engineering Society Audio Engineering Society Preprint, Munich, Germany: 126th Audio Engineering Society Convention 7729

    Abstract

    Experiments were undertaken to elicit the perceived effects of head-position-dependent variations in the interaural cross-correlation coefficient of a range of signals. A graphical elicitation experiment showed that the variations in the IACC strongly affected the perceived width and depth of the reverberant environment, as well as the perceived width and distance of the sound source. A verbal experiment gave similar results, and also indicated that the head-position-dependent IACC variations caused changes in the perceived spaciousness and envelopment of the stimuli.

  • Williams D, Brookes T. (2009) 'Perceptually-motivated audio morphing: softness'. Audio Engineering Society Convention Proceedings, Paper 7778, Munich, Germany: AES 126th Convention

    Abstract

    A system for morphing the softness and brightness of two sounds independently from their other perceptual or acoustic attributes was coded. The system is an extension of a previous one that morphed brightness only, that was based on the Spectral Modelling Synthesis additive/residual model. A Multidimensional Scaling analysis, of listener responses to paired comparisons of stimuli generated by the morpher, showed movement in three perceptually-orthogonal directions. These directions were labelled in a subsequent verbal elicitation experiment which found that the effects of the brightness and softness controls were perceived as intended. A Timbre Morpher, adjusting additional timbral attributes with perceptually-meaningful controls, can now be considered for further work.

  • Kim C, Mason RD, Brookes T. (2009) 'The role of head movement in the analysis of spatial impression'. Engineering and Physical Sciences Research Council London, UK: EPSRC People in Systems Theme Day
  • Mason RD, Kim C, Brookes T. (2008) 'Taking head movements into account in measurement of spatial attributes'. Institute of Acoustics Proceedings of the Institute of Acoustics Reproduced Sound Conference, Brighton, UK: Institute of Acoustics 24th Reproduced Sound Conference 30 (6), pp. 239-246.

    Abstract

    Measurements of the spatial attributes of auditory environments or sound reproduction systems commonly only consider a single receiver position. However, it is known that humans make use of head movement to help to make sense of auditory scenes, especially when the physical cues are ambiguous. Results are summarised from a three-year research project which aims to develop a practical binaural-based measurement system that takes head movements into account. Firstly, the head movements made by listeners in various situations were investigated, which showed that a wide range of head movements are made when evaluating source width and envelopment, and minimal head movements made when evaluating timbre. Secondly, the effect of using a simplified sphere model containing two microphones instead of a head and torso simulator was evaluated, and methods were derived to minimise the errors in measured cues for spatial perception that were caused by the simplification of the model. Finally, the results of the two earlier stages were combined to create a multi-microphone sphere that can be used to measure spatial attributes incorporating head movements in a perceptually-relevant manner, and which allows practical and rapid measurements to be made.

  • Kim C, Mason R, Brookes T. (2008) 'Improvements to a Spherical Binaural Capture Model for Objective Measurement of Spatial Impression with Consideration of Head Movements'. San Francisco, USA : Audio Engineering Society Audio Engineering Society Preprint, San Francisco, USA: 125th Audio Engineering Society Convention 7579

    Abstract

    This research aims, ultimately, to develop a system for the objective evaluation of spatial impression, incorporating the finding from a previous study that head movements are naturally made in its subjective evaluation. A spherical binaural capture model, comprising a head-sized sphere with multiple attached microphones, has been proposed. Research already conducted found significant differences in interaural time and level differences, and cross-correlation coefficient, between this spherical model and a head and torso simulator. It is attempted to lessen these differences by adding to the sphere a torso and simplified pinnae. Further analysis of the head movements made by listeners in a range of listening situations determines the range of head positions that needs to be taken into account. Analyses of these results inform the optimum positioning of the microphones around the sphere model.

  • Kim C, Mason R, Brookes T. (2008) 'Initial investigation of signal capture techniques for objective measurement of spatial impression considering head movement'. Audio Engineering Society Preprint Audio Engineering Society Preprint, Amsterdam, The Netherlands: 124th Audio Engineering Society Convention 7331

    Abstract

    In a previous study it was discovered that listeners normally make head movements attempting to evaluate source width and envelopment as well as source location. To accommodate this finding in the development of an objective measurement model for spatial impression, two capturing models were introduced and designed in this research, based on binaural technique: 1) rotating Head And Torso Simulator (HATS), and 2) a sphere with multiple microphones. As an initial study, measurements of interaural time difference (ITD), level difference (ILD) and cross-correlation coefficient (IACC) made with the HATS were compared with those made with a sphere containing two microphones. The magnitude of the differences was judged in a perceptually relevant manner by comparing them with the just-noticeable differences (JNDs) of these parameters. The results showed that the differences were generally not negligible, implying the necessity of enhancement of the sphere model, possibly by introducing equivalents of the pinnae or torso. An exception was the case of IACC, where the reference of JND specification affected the perceptual significance of its difference between the two models.

  • Brookes TS. (2007) 'Audio Perception, Measurement & Synthesis'. London, UK: Institution of Engineering and Technology (IET) Lecture Series
  • Brookes TS. (2007) 'Engineering the Senses: Psychoacoustics'. London, UK: The Science Museum Dana Centre Sound Workshop (supported by The Royal Academy of Engineering)
  • Brookes TS. (2007) 'Spatial Psychoacoustics & Creative Engineering'. York, UK: Audio Engineering Society (AES) National Student Fair
  • Kassier R, Brookes TS, Rumsey F. (2007) 'Training Versus Practice in Spatial Audio Attribute Evaluation Tasks'. Vienna: 122nd Audio Engineering Society Convention Convention Paper 7117
  • Williams D, Brookes TS. (2007) 'Perceptually-Motivated Audio Morphing: Brightness'. Audio Engineering Society Vienna: 122nd Audio Engineering Society Convention Convention Paper 7035
  • Kim C, Mason R, Brookes T. (2007) 'An investigation into head movements made when evaluating various attributes of sound'. Vienna, Austria : Audio Engineering Society Audio Engineering Society Preprint, Vienna, Austria: 122nd Audio Engineering Society Convention 7031
  • Kassier R, Brookes T, Rumsey F. (2006) 'A Comparison Between Spatial Audio Listener Training and Repetitive Practice'. San Francisco : Sound: 121st Audio Engineering Society Convention
  • Kassier R, Brookes T, Rumsey F. (2006) 'Designing a spatial audio attribute listener training system for optimal transfer'. Paris : Sound: 120th AES Convention
  • Brookes T, Paul M. (2006) 'Controlling the Perceived Spatial Orientation of a Reproduced Human Voice Source'. Sweden : Sound: 28th Conference of the Audio Engineering Society
  • Murphy D, Brookes T, Brereton J. (2006) 'SpACE-Net - The Spatial Audio Creative Engineering Network'. Sweden : Sound: 28th Conference of the Audio Engineering Society
  • Brookes T. (2005) 'The Spatial Audio Creative Engineering Network'. London : Sound: DMRN One-day Workshop
  • Kassier R, Brookes T, Rumsey F. (2005) 'A pilot study into listener training for spatial audio evaluation'. Glasgow : Sound: DMRN Summer Conference
  • Kassier R, Lee HK, Brookes T, Rumsey F. (2005) 'An informal comparison between surround-sound microphone techniques'. Barcelona : Sound: 118th AES Convention
  • Brookes T, Treble C. (2005) 'The effect of non-symmetrical left/right recording pinnae on the perceived externalisation of binaural recordings'. Barcelona : Sound: 118th AES Convention
  • Brookes T, Neher T. (2005) 'Perceptually Unidimensional Control of Spatial Audio: a Pilot study'. London : Sound: DMRN One-day Workshop
  • Mason R, Brookes T, Rumsey F. (2004) 'Development of the interaural cross-correlation coefficient into a more complete auditory width prediction model'. Kyoto, Japan : International Congress on Acoustics Proceedings of the 18th International Congress on Acoustics, Kyoto, Japan: 18th International Congress on Acoustics IV, pp. 2453-2456.

    Abstract

    Auditory width measurements based on the interaural cross-correlation coefficient (IACC) are often used in the field of concert hall acoustics. However, there are a number of problems with such measurements, including large variations around the centre of a room and a limited range of values at low frequencies. This paper explores how some of these problems can be solved by applying the IACC in a more perceptually valid manner and using it as part of a more complete hearing model. It is proposed that measurements based on the IACC may match the perceived width of stimuli more accurately if a source signal is measured rather than an impulse response, and when factors such as frequency and loudness are taken into account. Further developments are considered, including methods to integrate the results calculated in different frequency bands, and the temporal response of spatial perception

  • Mason R, Brookes T. (2004) 'Perception, measurement and synthesis of spatial impression'. London : Sound: Audio Engineering Society British Section Lecture
  • Brookes T, Mason R. (2004) 'Perceptually Motivated Measurement and Control of Digital Music'. York : Sound: The Future of Audio: Digital Music in 2010 (DMRN Conference)
  • Kassier R, Brookes T, Rumsey F. (2004) 'A simplified scene-based paradigm for use in spatial audio listener training applications'. San Francisco : Sound: 117th AES Convention
  • Neher T, Brookes T, Rumsey F. (2004) 'Unidimensional simulation of the spatial attribute 'ensemble depth’ for training purposes - Part 2: creation and validation of reference stimuli'. Berlin, Germany : Sound: 116th AES Convention
  • Supper B, Brookes T, Rumsey F. (2004) 'A lateral angle tool for spatial auditory analysis'. Berlin, Germany : Sound: 116th AES Convention
  • Mason R, Brookes T, Rumsey F. (2004) 'Integration of measurements of interaural cross-correlation coefficient and interaural time difference within a single model of perceived source width'. San Francisco, USA : Audio Engineering Society Preprint, San Francisco: 117th Audio Engineering Society Convention 6137
  • Mason R, Brookes T, Rumsey F. (2004) 'Evaluation of an auditory source width prediction model based on the interaural cross-correlation coefficient'. San Diego, California : Journal of the Acoustical Society of America, Sound: 148th meeting of the Acoustical Society of America 116
  • Mason R, Brookes T, Rumsey F. (2004) 'Spatial impression: measurement and perception of concert hall acoustics and reproduced sound'. Hyogo, Japan : Proceedings of the International Symposium on Room Acoustics, Hyogo, Japan: International Symposium on Room Acoustics: Design and Science

    Abstract

    Auditory width measurements based on the interaural cross-correlation coefficient (IACC) are often used in the field of concert hall acoustics. However, there are a number of problems with such measurements, including large variations around the centre of a room and a limited range of values at low frequencies. This paper explores how some of these problems can be solved by applying the IACC in a more perceptually valid manner and using it as part of a more complete hearing model. It is proposed that measurements based on the IACC may match the perceived width of stimuli more accurately if a source signal is measured rather than an impulse response, and when factors such as frequency and loudness are taken into account. Further developments are considered, including methods to integrate the results calculated in different frequency bands, and the temporal response of spatial perception

  • Neher T, Rumsey F, Brookes TS, Craven P. (2003) 'Unidimensional simulation of the spatial attribute 'ensemble width' for training purposes'. Amsterdam: 114th Audio Engineering Society Convention preprint 5769
  • Mason R, Brookes T, Rumsey F. (2003) 'Creation and verification of a controlled experimental stimulus for investigating selected perceived spatial attributes'. Amsterdam : Audio Engineering Society Preprint, Amsterdam: 114th Audio Engineering Society Convention 5771
  • Supper B, Brookes T, Rumsey F. (2003) 'A new approach to detecting auditory onsets within a binaural stream'. Amsterdam : Sound: 114th AES Convention
  • Brookes T. (2003) 'The Psychoacoustics of Sound Recording'. London : Sound: The Future of Digital Music Research (Digital Music Research Network Workshop)
  • Neher T, Brookes T, Rumsey F. (2003) 'Unidimensional simulation of the spatial attribute 'ensemble depth' for training purposes. Part 1: pilot study into early reflection pattern characteristics'. Banff, Canada : Sound: AES 24th International Conference on Multichannel Audio, pp. 123-137.
  • Mason R, Brookes T, Rumsey F. (2002) 'The perceptual relevance of extant techniques for the objective measurement of spatial impression'. London : Proceedings of the Institute of Acoustics, London: Auditorium Acoustics 2002 Conference 24
  • Brookes T. (2002) 'The Institute of Sound Recording'. London : Sound: Digital Music Research Network Launch Day
  • Neher T, Brookes T. (2002) 'Training of Listeners for the Evaluation of Spatial Sound Reproduction'. Munich, Germany : Sound: 112th AES Convention,
  • Brookes T. (2001) 'A speech-based frequency scale'. Amsterdam: 110th AES Convention
  • Brookes TS. (1999) 'What Does the Mind's Ear See?'. Oslo, Norway: 6th International Conference on Systematic and Comparative Musicology
  • Howard DM, Tyrrell AM, Brookes TS. (1997) 'Spectrography by Human Hearing Modelling'. 22/03/1997: Audio Engineering Society 102nd Convention preprint 4485
  • Tyrrell AM, Brookes TS, Howard DM. (1997) 'T9000 and T800 transputers: A real-time application'. ELSEVIER SCIENCE BV JOURNAL OF SYSTEMS ARCHITECTURE, COMO, ITALY: Euromicro Conference 95 43 (1-5), pp. 341-344.
  • Brookes TS, Tyrrell AM, Howard DM. (1996) 'Musical Analysis using a Real-Time model of Peripheral Hearing'. Hong Kong: Proceedings of the International Computer Music Conference (ICMC), pp. 79-82.
  • Brookes TS, Howard DM, Tyrrell AM. (1995) 'T800/T9000 Communications: A Programmer's View'. IOS Press (Oxford) Harrogate, UK: Transputer Applications and Systems '95: Proceedings of the 1995 World Transputer Congress, pp. 18-28.
  • Brookes TS, Howard DM, Tyrrell AM. (1994) 'Simulations of the Human Peripheral Hearing System: A Comparison of T800 and T9000'. Nottingham, UK: Proceedings of the VIII P.L.U.G. Conference, pp. 17-24.
  • Brookes TS, Howard DM, Tyrrell AM. (1994) 'A T9000 Simulation of the Human Peripheral Hearing System'. London, UK: Institution of Electrical Engineers Digest 208, pp. 4.1-4.4.

Book chapters

  • Hummersone C, Stokes T, Brookes T. (2014) 'On the Ideal Ratio Mask as the Goal of Computational Auditory Scene Analysis'. in Naik GR, Wang W (eds.) Blind Source Separation: Advances in Theory, Algorithms and Applications Berlin/Heidelberg : Springer Article number 12 , pp. 349-368.

Posters

  • Pike C, Mason RD, Brookes TS. (2014) Auditory adaptation to static spectra. UKSpeech Conference, Edinburgh

    Abstract

    Auditory adaptation is thought to reduce the perceptual impact of static spectral energy and increase sensitivity to spectral change. Research suggests that this adaptation helps listeners to extract stable speech cues across different talkers, despite inter-talker spectral variations caused by differing vocal tract acoustics. This adaptation may also be involved in compensation for distortions caused by transmission channels more generally (e.g. distortions caused by the room or loudspeaker through which a sound has passed). The magnitude of this adaptation and its ecological importance has not been established. The physiological and psychological mechanisms behind adaptation are also not well understood. The current research aimed to confirm that adaptation to transmission channel spectrum occurs when listening to speech produced though two types of transmission channel: loudspeakers and rooms. The loudspeaker is analogous to the vocal tract of a talker, imparting resonances onto a sound source which reaches the listener both directly and via reflections. The room-affected speech however, reaches the listener only via reflections – there is no direct path. Larger adaptation to the spectrum of the room was found, compared to adaptation to the spectrum of the loudspeaker. It appears that when listening to speech, mechanisms of adaptation to room reflections, and adaptation to loudspeaker/vocal tract spectrum, may be different.

  • Brookes T, Hummersone C. (2010) Machine Listening for Sound Quality Evaluation. Machine Listening Workshop 2010, Queen Mary University of London
  • Hummersone C, Mason R, Brookes T. (2010) A perceptually–inspired approach to machine sound source separation in real rooms. University of Surrey Postgraduate Research Conference
  • Evans W, Mason R, Brookes T. (2010) A system for the auralisation of synthetic sound scenes using headphones and head-tracking. University of Surrey Postgraduate Research Conference

    Abstract

    Auralisation is the process of rendering virtual sound fields. It is used in areas including: acoustic design, defence, gaming and audio research. As part of a PhD project concerned with the influence of loudspeaker directivity on the perception of reproduced sound, a fully-computed auralisation system has been developed. For this, acoustic modelling software is used to synthesise and extract binaural impulse responses of virtual rooms. The resulting audio is played over headphones and allows listeners to experience the excerpt being reproduced within the synthesised environment. The main advance with this system is that impulse responses are calculated for a number of head positions, which allows the listeners to move when listening to the recreated sounds. This allows for a much more realistic simulation, and makes it especially useful for conducting subjective experiments on sound reproduction systems and/or acoustical environments which are either not available or are even impractical to create. Hence, it greatly increases the range and type of experiments that can be undertaken at Surrey. The main components of the system are described, together with the results from a validation experiment which demonstrate that this system provides similar results to experiments conducted previously using loudspeakers in an anechoic chamber.

Theses and dissertations

  • Brookes TS. (1997) A Real-Time Auditory Spectrograph. University of York, UK

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