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Journal of the Audio Engineering Society

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2015 November - Volume 63 Number 11

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Papers

Feature-Based Analysis of the Effects of Packet Delay on Networked Musical Interactions

Authors: Rottondi, Cristina; Buccoli, Michele; Zanoni, Massimiliano; Garao, Dario; Verticale, Giacomo; Sarti, Augusto

When musicians at multiple physical locations attempt to play together, the limiting factor is unavoidable packet delays and jitter introduced by the IP network that connects them together. This research investigates the musical tolerance of adverse network conditions as a function of rhythmic complexity and tempo. Results show that with higher network latency: (a) musicians exhibit a more pronounced tendency to decelerate with more rhythmically complex pieces; (b) rhythmical complexity does not significantly worsen musician perception of the delay and interaction quality; (c) among the timbral features, instruments with a higher spectral entropy and spectral flatness (such as guitars and drums) lead to larger tempo slowdown. Low-latency networks promise to revolutionize interactive music such as remote rehearsals and music teaching.

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Comparative Evaluation of Radio and Audio Logo Sound Designs

Authors: McGregor, Iain Peter; Cunningham, Stuart

This study aims to explore the suitability of capturing designers’ and listeners’ experiences of sound design for a radio drama and audio logos using the repertory grid technique, which is a proven method of information elicitation based on Personal Construct Theory. Sound designs that incorporate sound effects, music, or dialogue can be broken down into discrete sound events that can then be rated using attributes that are meaningful to both designers and listeners. A method for evaluating sound without training casual listeners and without depending on expert listeners is presented. A number of the constructs show strong matches between the sound’s designers and listeners, indicating that these constructs have value as a common vocabulary and can be used to mediate and articulate audio features between the two.

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Audiovisual Spatial Coherence for 2D and Stereoscopic-3D Movies

Authors: Hendrickx, Etienne; Paquier, Mathieu; Koehl, Vincent

In movie theaters, sound sources such as dialog are often reproduced on the center loudspeaker without regard to the visual position on screen. Some sound engineers and researchers have suggested that spatial audiovisual coherence could improve the audience experience, especially for stereoscopic-3D (s-3D) movies. In the experiment described, subjects were asked to judge the suitability of several soundtracks for eight s-3D sequences. Depending on the soundtrack, sound sources could be more or less coherent in azimuth and depth. Results showed that sound suitability could be significantly improved for most of the sequences when coherence in azimuth was achieved. An improvement in the experience of depth was only observed with one sequence. When sequences were presented in nonstereoscopic (2D) version, there was no significant effect of stereoscopy. Subjects quickly became accustomed to azimuthal coherence, which improved sound suitability throughout the experiment. This suggests that the audience adaptation to a new cinematographic convention regarding spatialization of sound objects would not be a burden.

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Perceptual Quality Improvement and Assessment for Virtual Bass Systems

Authors: Mu, Hao; Gan, Woon-Seng

Because of size limitation and cost constraints, small loudspeakers cannot efficiently reproduce the sound in the low-frequency range, resulting in poor bass perception and a lack of strong rhythms. A psychoacoustic bass enhancement system, known as the virtual bass system (VBS), enhances the perception of bass reproduced by small loudspeakers by tricking the human auditory system into perceiving bass that does not physically exit. A VBS is based on the psychoacoustic phenomenon called the missing fundamental effect, wherein the higher harmonics of the fundamental frequency can produce the sensation of the fundamental frequency. However, these harmonics can result in perceived distortion. This report describes two techniques to improve the audio quality of the VBS, including an improved hybrid VBS and the timbre matching weighting. Objective and subjective tests are presented to compare the performance of the proposed and the conventional VBS techniques.

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Engineering reports

Spatial Analysis and Synthesis of Car Audio System and Car Cabin Acoustics with a Compact Microphone Array

Authors: Tervo, Sakari; Pätynen, Jukka; Kaplanis, Neofytos; Lydolf, Morten; Bech, Søren; Lokki, Tapio

This research proposes a spatial sound analysis and synthesis approach for automobile sound systems, where the acquisition of the measurement data is much faster than with the Binaural Car Scanning method. This approach avoids the problems that are typically found with binaural reproduction and dummy head measurements. In combination with a compact microphone array, the approach is based on the recently introduced parametric spatial sound analysis method, called the Spatial Decomposition Method (SDM). An objective analysis of the sound field with respect to direction and energy enables the synthesis of multichannel loudspeaker reproduction. Because of the extreme acoustics of an automobile cabin, the authors recommend several steps to improve both the objective and perceptual performance. Because SDM is a parametric approach to spatial impulse response analysis, this allows automobile audio systems to be tuned in a laboratory environment instead of in-situ.

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Standards and Information Documents

AES Standards Committee News

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Features

Psychoacoustics Meets Engineering

Authors: Rumsey, Francis

[Feature] The latest research in applied psychoacoustics was presented at recent AES conventions with an emphasis on measuring parameters relevant to practical engineeing challenges and listener preferences.

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Sound Board: Can We Stop the Loudness War in Streaming?

Authors: Katz, Bob

[Feature] While artists have the theoretical freedom to produce masters at any level they wish with any sound they wish, the majority of popular music produced today is mastered to the level of the highest streaming provider or higher. Why? Because artists do not want to perceive their music to be lower than the highest stream they hear. Streaming loudness is a much worse situation than broadcast radio or CD, because artists can directly compare their own audio files against streams and Internet radio on their own computer speakers. What can we as engineers do to repair the situation? As cochair of an AES Technical Council study group on streaming loudness, my group produced “Recommendation for Loudness of Audio Streaming and Network File Playback” version 1.0. I urge all active engineers to spread the word about this document, which is the first step in addressing the problem.

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