The Journal of the Audio Engineering Society — the official publication of the AES — is the only peer-reviewed journal devoted exclusively to audio technology. Published 10 times each year, it is available to all AES members and subscribers.
The Journal contains state-of-the-art technical papers and engineering reports; feature articles covering timely topics; pre and post reports of AES conventions and other society activities; news from AES sections around the world; Standards and Education Committee work membership news, new products, and newsworthy developments in the field of audio.
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Authors: Frankenbach, Cornelius; Herzog, Carsten; Seitz, Julia; Fels, Janina
In a listening experiment with 24 participants, the localization accuracy of dynamic binaural synthesis employing individual and estimated head-related transfer functions (HRTFs) was compared to the localization accuracy with generic HRTFs in vertical and horizontal direction. The experiment featured five different HRTF estimation methods, high-frequency audiometry, proximal pointing, and individual headphone equalization. While generic Knowles Electronics Mannikin for Acoustic Research (KEMAR) HRTFs served as a baseline, individually measured ones provided a reference. Estimated HRTFs were acquired based on anthropometric data and 3D head models by means of an interaural time difference adaptation, a selection from an HRTF database, a principal component-based synthesis, and a numerical HRTF simulation. Compared to the KEMAR, measured and estimated HRTFs produced significantly smaller vertical errors, while differences in terms of the horizontal error were not significant. The HRTF synthesis qualified as the preferred estimation method by significantly reducing the vertical error for virtual sources on and below the horizontal plane, compared to the generic HRTFs.
Authors: Herzog, Stephan
Acoustic loudspeaker measurements are an essential aspect in loudspeaker development and design. Established setups usually require acoustic measurement rooms or chambers where the speaker under test has to be installed for conducting the tests. Furthermore, typical spatial measurements require that the speaker has to be rotated on one or two axes. In addition to the traditional approach, there are different methods that use near-field measurements where the microphone is usually moved and the loudspeaker remains at a fixed position. Both techniques commonly make measurements at discrete points or angles in the spatial domain. In this article, the idea of making impulse response measurements in the near-field while the microphone is in movement is proposed and described. This approach leads to much faster results that can be comparable to the results of fixed-point measurements. The focus here is on the properties and the resulting processing of appropriate test signals and on the experimental verification of the method. This method will be applied to the measurement of line arrays, where directivity is of high interest, but it can also be used for other loudspeaker configurations.
Authors: Puigt, Matthieu; Bigot, Benjamin; Devulder, Hélène
Cockpit voice recorders (CVRs) are one of the two mandatory flight recording devices embarked in commercial aircraft. Its analysis is crucial to understand the context of an air incident or accident. However, in such scenarios, when the audio recordings are usable, CVR may contain strong mixtures of crew member speech signals, radio communications, and cockpit alarms. However, contrary to the “cocktail party problem” that blind source separation (BSS) aims to tackle, modeling CVR mixtures—that are here named the “cockpit party problem”—was never done before. In this paper, the authors thus propose a CVR mixture model and highlight its limitations. While not trivial—even in a two-source scenario—BSS methods can be applied to real CVR recordings. It is found that taking into account several BSS outputs provided by various methods may help audio analysts to transcribe the CVR data. That is, near 90% of unintelligible words can be transcribed from CVR recordings processed by BSS methods.
Authors: Ziemer, Tim; Kudakov, Nikita; Reuter, Christoph
In hip hop music, rappers and producers play important but rather different roles. However, both contribute to the overall sound, as rappers bring in their voice, while producers are responsible for the music composition and mix. In this case report, the authors trained self-organizing maps with songs produced by Dr. Dre, Rick Rubin, and Timbaland using the goniometer and mel-frequency cepstral coefficients. With these maps, the authors investigate whether hip hop producers have a unique sound profile. Then, they test whether collaborations with the rappers Eminem, Jay-Z, LL Cool J, and Nas stick to or break out of this sound profile. As these rappers are also producers of some songs, it was investigated how much their sound profile was influenced by the producers who introduced them to beat making. The results speak a clear language: producers have their own sound profile that is unique concerning the goniometer and less distinct concerning mel-frequency cepstral coefficients. They dominate the sound of hip hop music over rappers, who emulate the sound profile of the producers who introduced them to beat making.
Authors: Munroe, Oliver; Novak, Antonin; Simon, Laurent; Massicotte, Daniel
This paper presents a way of modeling the effect of eddy currents on the inductance of a loudspeaker coil over a wide frequency bandwidth without the use of fractional derivatives or Foster/Cauer networks. The model presented is a physics-based model, which is derived from Maxwell’s equations and discretized in space. The model is compared with finite element analysis simulations and measurement data. The results show an excellent agreement with the reference data over the audio bandwidth and for different coil positions. Using eight parameters, of which four require fitting and only two are dependent on the coil position, the model is simple to fit to reference data and may be vectorized for real-time applications.
Authors: Anderson, David A.
Flat-panel loudspeaker exciters are moving coil motors with a coupling surface, often shaped like a ring or disc, that attaches to the surface of a plate. Simulations normally treat the exciter as acting like a point force, but in reality, the ring or disc shape can have a significant influence on the frequency response of the plate at middle and high frequencies. Equations to model the effects of disc and ring shapes are introduced, and simulations demonstrate that these exciter coupling shapes impose a low-pass filtering effect with sharp nodes in the frequency response of the vibrating surface, with rings having a lower cutoff frequency than discs. Comparisons between simulation and experimental data are provided.
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