AES London 2011
Poster Session P9

P9 - Perception and Evaluation

Saturday, May 14, 09:00 — 10:30 (Room: Foyer)

P9-1 The Effect of Loudness Overflow on Equal-Loudness-Level ContoursAndrew J. R. Simpson, Joshua D. Reiss, Queen Mary University of London - London, UK
This paper presents a formal derivation of the Loudness Overflow Effect (LOE), which describes the impact of nonlinear distortion on loudness. Computational analysis is then performed, comprised of two experiments involving two compressive static nonlinearities and using two well-known time-varying loudness models. The results characterize the nonlinearities in terms of LOE as a function of frequency and of listening level in the case of 250-ms pure-tone stimuli, and in terms of the traditional equal-loudness-level contours. The analysis is then extended to synthesized wind instruments for one of the nonlinearities. The effect of the nonlinearity on loudness as a function of musical note fundamental frequency and listening level is described for various synthesized instruments.
Convention Paper 8367 (Purchase now)

P9-2 Evaluating the Use of Audio Smartphone Apps for Higher EducationAnne Nortcliffe, Andrew Middleton, Ben Woodcock, Sheffield Hallam University - Sheffield, UK
Digital audio technology has garnered interest in Education recently, being deployed by early adopter academics to provide audio feedback. Students have also used it, gathering audio notes on their personal devices to enhance their learning. However, the sharing and distributing of the recordings is time-consuming and requires separate technology. Smartphones with audio apps are able to support recording and distribution/sharing of learning conversations more effectively because of their additional customizable and integrated functionality. This is attractive to Education now that it is clear that smartphones are becoming ubiquitous on campus. This paper describes an evaluation of audio apps for recording learning conversations by an academic and students and their experience in using smartphone audio apps to date.
Convention Paper 8368 (Purchase now)

P9-3 A Study of Human Perception of Temporal and Spectral Distortion Caused by Subwoofer ArraysElena Shabalina, RWTH Aachen University - Aachen, Germany; Janko Ramuscak, d&b audiotechnik GmbH - Backnang, Germany; Michael Vorländer, RWTH Aachen University - Aachen, Germany
The key task for a sound reinforcement system is to provide an even sound pressure level distribution over the whole listening area with possibly the same frequency response; and reduce radiation in wrong directions. For that a system should show a certain directivity, which for low frequencies can be achieved only by using multiple sound sources, for example, placed in a row in front of the stage. This technique can help to avoid strong interference and corresponding space sound pressure level variations of the conventional left/right setup of subwoofers. On the other hand, multiple sources cause changes of the impulse and frequency response of an array. Listening tests showed that these changes are audible for experienced listeners.
Convention Paper 8369 (Purchase now)

P9-4 Evaluation of the Psychoacoustic Perception of Geometric Acoustic Modeling-Based AuralizationAglaia Foteinou, Damian T. Murphy, University of York - Heslington, York, UK
The subjective evaluation of the auralization of a simulated acoustic, with a view to establishing the success or otherwise of the results obtained, is usually best achieved using listening tests comparing the virtual environment with the actual measured space. As existing modeling methods still need to be improved, it is of critical importance to focus on the human perception of acoustic of the given space, rather than optimizing room acoustic parameters based only on objective measures. This paper uses a much simplified representation of a space with the resulting computer model giving the capability to control all of the examined acoustic or simulation parameters independently. A 3-D shoebox shape room is created and a variety of factors are changed every time in order to investigate their relevance and influence on human perception. These results are obtained from listening tests, and conclusions for the psychoacoustic perception of such a space are given.
Convention Paper 8370 (Purchase now)

P9-5 A Comparative Perceptual Evaluation of the Timbral Variations in Choral Location Recordings Created by Four Common Stereo Microphone TechniquesDuncan Williams, University of Oxford (Wolfson College) - Oxford, UK
Choral recordings created on location were evaluated perceptually to determine the nature of the variations in timbre that might be elicited by the use of different stereo microphone techniques. Four stereo recordings were made simultaneously with coincident, near coincident, and spaced stereo microphone techniques. Listeners were invited to describe any perceived changes through a verbal elicitation experiment, informing an adjective “pool” of possible attributes. These attributes were reduced in number to six by verbal protocol analysis. The six remaining attributes were then scaled in a second listening experiment. Mean and standard deviation values in the results suggested that there was variation in three timbral attributes. This illustrated that the manipulation of timbral attributes by microphone technique, combined with perceptual analysis, is possible.
Convention Paper 8371 (Purchase now)

P9-6 Anchor Signals Validation for Two Dimensions of a Four-Dimensional Perceptive SpaceYves Zango, Orange Labs Lannion Tech/Opera - Lannion Cedex, France, INSERM U642, Rennes France, Université de Rennes, Rennes France; Régine Le Bouquin-Jeannès, INSERM U642 - Rennes France, Université de Rennes, Rennes France; Nathalie Costet, INSERM U642 - Rennes France, Université de Rennes, Rennes France; Catherine Quinquis, Orange Labs Lannion Tech/Opera - Lannion Cedex, France
The subjective assessment of speech and sound codecs requires anchor signals to ensure its reliability. The reference system currently used is Modulated Noise Reference Unit (MNRU), which simulates only quantization noise. Now, the new generations of codecs present other impairments. In this study we consider speech quality as a multidimensional phenomenon and use dimensional reduction techniques to project codecs' impairments in a four-dimensional space, each axis of the perceptive space corresponding to one of them. A verbalization test allowed characterizing two of these dimensions by the following attributes: “muffle” and “background noise.” Anchor signals were designed for these two dimensions, and a statistical analysis allowed validating the accuracy of at least one of these signals.
Convention Paper 8372 (Purchase now)

P9-7 Auditory Distance Perception: Criteria and Listening RoomJean-Christophe Messonnier, Conservatoire de Paris CNSMDP - Paris, France; Alban Moraud, Altia - Paris, France
This paper is the result of a series of listening experiments carried out to investigate the correlation between auditory distance and two criteria: the ratio of direct to reverberant sound energy and the clarity C80. In the first section of this paper we will determine which of the two criteria is more efficient. The second section compares the values of these criteria when the same signal is played on a well damped control room loudspeaker system and when it is played on a domestic stereophonic loudspeaker system. A second series of listening experiments shows how the auditory distance is perceived in both cases.
Convention Paper 8373 (Purchase now)

P9-8 Subjective Comparison between Stereo and Binaural Processing from B-Format Ambisonic Raw Audio MaterialFábio W. Sousa, University of York - York, North Yorkshire, UK
Using audio recorded in Ambisonic B-format from a sound field microphone and processed through both stereo and binaural tools, a subjective comparison is made. Hearing tests were performed taking into account personal experience and preference, as well as some spatial attributes concepts defined in previous works. Aiming to evaluate the real effectiveness of binaural processing, this paper considers the possibility of distributing contemporary music, originally developed for Ambisonic reproduction, through either conventional stereo or a method of high fidelity spatial processing directed specifically to reproduction through headphone systems, based on binaural technology. The sound images represented in both binaural and stereo processing are examined. Spatial attributes like wideness, depth, naturalness, and presence are evaluated.
Convention Paper 8374 (Purchase now)

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