AES Show: Make the Right Connections Audio Engineering Society

AES San Francisco 2008
Paper Session P14

Saturday, October 4, 9:00 am — 12:00 pm

P14 - Listening Tests & Psychoacoustics

Chair: Poppy Crum, Johns Hopkins University - Baltimore, MD, USA

P14-1 Rapid Learning of Subjective Preference in EqualizationAndrew Sabin, Bryan Pardo, Northwestern University - Evanston, IL, USA
We describe and test an algorithm to rapidly learn a listener’s desired equalization curve. First, a sound is modified by a series of equalization curves. After each modification, the listener indicates how well the current sound exemplifies a target sound descriptor (e.g., “warm”). After rating, a weighting function is computed where the weight of each channel (frequency band) is proportional to the slope of the regression line between listener responses and within-channel gain. Listeners report that sounds generated using this function capture their intended meaning of the descriptor. Machine ratings generated by computing the similarity of a given curve to the weighting function are highly correlated to listener responses, and asymptotic performance is reached after only ~25 listener ratings.
Convention Paper 7581 (Purchase now)

P14-2 An Initial Validation of Individualized Crosstalk Cancellation Filters for Binaural Perceptual ExperimentsAlastair Moore, Anthony Tew, University of York - York, UK; Rozenn Nicol, France Télécom R&D - Lannion, France
Crosstalk cancellation provides a means of delivering binaural stimuli to a listener for psychoacoustic research that avoids many of the problems of using headphone in experiments. The aim of this study was to determine whether individual crosstalk cancellation filters can be used to present binaural stimuli, which are perceptually indistinguishable from a real sound source. The fast deconvolution with frequency dependent regularization method was used to design crosstalk cancellation filters. The reproduction loudspeakers were positioned at ±90-degrees azimuth and the synthesized location was 0-degrees azimuth. Eight listeners were tested with three types of stimuli. In twenty-two out of the twenty-four listener/stimulus combinations there were no perceptible differences between the real and virtual sources. The results suggest that this method of producing individualized crosstalk cancellation filters is suitable for binaural perceptual experiments.
Convention Paper 7582 (Purchase now)

P14-3 Reverberation Echo Density PsychoacousticsPatty Huang, Jonathan S. Abel, Hiroko Terasawa, Jonathan Berger, Stanford University - Stanford, CA, USA
A series of psychoacoustic experiments were carried out to explore the relationship between an objective measure of reverberation echo density, called the normalized echo density (NED), and subjective perception of the time-domain texture of reverberation. In one experiment, 25 subjects evaluated the dissimilarity of signals having static echo densities. The reported dissimilarities matched absolute NED differences with an R2 of 93%. In a 19-subject experiment, reverberation impulse responses having evolving echo densities were used. With an R2 of 90% the absolute log ratio of the late field onset times matched reported dissimilarities between impulse responses. In a third experiment, subjects reported breakpoints in the character of static echo patterns at NED values of 0.3 and 0.7.
Convention Paper 7583 (Purchase now)

P14-4 Optimal Modal Spacing and Density for Critical ListeningBruno Fazenda, Matthew Wankling, University of Huddersfield - Huddersfield, West Yorkshire, UK
This paper presents a study on the subjective effects of modal spacing and density. These are measures often used as indicators to define particular aspect ratios and source positions to avoid low frequency reproduction problems in rooms. These indicators imply a given modal spacing leading to a supposedly less problematic response for the listener. An investigation into this topic shows that subjects can identify an optimal spacing between two resonances associated with a reduction of the overall decay. Further work to define a subjective counterpart to the Schroeder Frequency has revealed that an increase in density may not always lead to an improvement, as interaction between mode-shapes results in serious degradation of the stimulus, which is detectable by listeners.
Convention Paper 7584 (Purchase now)

P14-5 The Illusion of Continuity Revisited on Filling Gaps in the Saxophone SoundPiotr Kleczkowski, AGH University of Science and Technology - Cracow, Poland
Some time-frequency gaps were cut from a recording of a motif played legato on the saxophone. Subsequently, the gaps were filled with various sonic material: noises and sounds of an accompanying band. The quality of the saxophone sound processed in this way was investigated by listening tests. In all of the tests, the saxophone seemed to continue through the gaps, an impairment in quality being observed as a change in the tone color or an attenuation of the sound level. There were two aims of this research. First, to investigate whether the continuity illusion contributed to this effect, and second, to discover what kind of sonic material filling the gaps would cause the least deterioration in sound quality.
Convention Paper 7585 (Purchase now)

P14-6 The Incongruency Advantage for Sounds in Natural ScenesBrian Gygi, Veterans Affairs Northern California Health Care System - Martinez, CA, USA; Valeriy Shafiro, Rush University Medical Center - Chicago, IL, USA
This paper tests identification of environmental sounds (dogs barking or cars honking) in familiar auditory background scenes (street ambience, restaurants). Initial results with subjects trained on both the background scenes and the sounds to be identified showed a significant advantage of about 5% better identification accuracy for sounds that were incongruous with the background scene (e.g., a rooster crowing in a hospital). Studies with naïve listeners showed this effect is level-dependent: there is no advantage for incongruent sounds up to a Sound/Scene ratio (So/Sc) of –7.5 dB, after which there is again about 5% better identification. Modeling using spectral-temporal measures showed that saliency based on acoustic features cannot account for this difference.
Convention Paper 7586 (Purchase now)