On the use of subjective HTRF evaluations for creating global perceptual similarity metrics of assessors and assessees

Presented at the 21st International Conference on Auditory Display (ICAD2015), July 6-10, 2015, Graz, Styria, Austria.In the absence of a well suited measure for quantifying binaural data variations, this study presents the use of a global perceptual distance metric which can describe both HRTF as well as listener similarities. The metric is derived based on subjective evaluations of binaural renderings of a sound moving along predefined trajectories in the horizontal and median planes. Its characteristics and advantages in describing data distributions based on perceptually relevant attributes are discussed. In addition, the use of 24 HRTFs from two different databases of origin allows for an evaluation of the perceptual impact of some database-dependent characteristics on spatialization. The effectiveness of the experimental design as well as the correlation between the HRTF evaluations of the two plane trajectories are also discussed

EVAA: A platform for experimental virtual archeological-acoustics to study the influence of performance space

International audienceResearch in historical musical acoustics has for several decades focused significantly on instrument fabrication. Such research has been able to highlight the acoustical impact of material and construction choices. Musicolog-ical studies have concentrated in parallel on understanding historical notation, playing styles, and even changes in musician posture over the centuries. In studying player and listener conditions in these historical studies, little attention has been given to the acoustical conditions of the performance, aside from extreme cases such as cathedral acoustic conditions. Extending the methodologies of experimental archaeology, recent advances in computational accuracy of acoustic virtual reality simulations offer the possibility to create ecologically valid reconstructions of historic sites. We present the development of an interactive immersive real-time simulator allowing musicians to perform "live" within virtual reconstructions of historic venues, comprising real-time adaptation of source directives with performer movements, rendered in Higher Order Ambisonics. Observations of the impact of acoustic variations on player performance, and the comparisons of the resulting performance between historically suitable venues and modern performance spaces from an audience perspective will complete the feedback loop between performer and listener necessary for a full understanding of the historical musical context

Proceedings of the EAA Spatial Audio Signal Processing symposium: SASP 2019

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Exploring cultural heritage through acoustic digital reconstructions

The fire at Notre Dame Cathedral in Paris in 2019 and the one at Gran Teatro La Fenice opera hall in Venice in 1996 are reminders of the fragile nature of humanity’s cultural heritage. Fortunately, acoustic measurements, numerical simulations, and digital reconstructions can recover— and to some extent preserve— the sound of humanity’s great architectural sites. What’s more, those techniques provide a way for archaeologists, historians, musicologists, and the general public to experience the lost acoustics of damaged or destroyed places

Inter-frequency band correlations in auditory filtered median plane HRTFs

International audienceSpectral cues in head-related transfer functions (HRTF), such as peaks and notches occurring above 4 kHz, are important for sound localization in the median plane. However, it may be complicated for the auditory system to detect absolute frequency and level peaks and notches, mapping them to three-dimensional positions. In contrast, it may be more reasonable that comparisons are made of the relative level differences between frequency bands due to various peaks and notches. With this approach, it is not necessary to detect peaks and notches directly, only comparisons in levels across frequency bands are needed. In this paper, we analyze level changes of median plane HRTFs in narrow frequency bands using auditory filters and inter-band correlations. These changes are investigated to clarify effects of peaks and notches on comprehensive level changes in the corresponding HRTFs.We investigated 105 HRTF sets from the RIEC (Research Institution of Electrical Communication, Tohoku University) database, available in the SOFA format standard. HRTFs were measured using a spherical loudspeaker array at RIEC for individual listeners. Head-related impulse responses (HRIRs) were acquired in the median plane from front (0°) to rear (180°) in 10°-steps. Each HRIR was then filtered by a band limited auditory filter. A Gammatone filter was employed in this analysis, with 40 equivalent rectangular bandwidth (ERB) over the full audible frequency range (up to 20 kHz). Output power level of the filtered HRIRs for the 19 median plane angles was calculated, resulting in 760 values (19 angles x 40 bands) for each listener. From these values, the level change of individual frequency bands was obtained as a function of angle in median plane. We then calculated the correlation across frequency bands for the level change as a function of angle. This produced 39 cross-correlation values and 1 auto-correlation for each band with a correlation matrix of 40 bands x 40 bands for each listener. Examination of the correlation matrixes showed similarities that could be summarized by clustering the analyzed bands into the following five aggregated approximate frequency bands:Band-1: 0 to 0.7 kHz, almost no level changes observed.Band-2: 0.7 to 1 kHz, observed negative correlation to odd bands (Band-1, Band-3, Band-5, level changes approximately 3 dB.Band-3: 1 kHz to 6 kHz, as the median plane angle increases, observed level decreases by approximately 5 dB.Band-4: 6 kHz to 10 kHz, observed level decreases as the median plane angle exceeds 120°. Observed negative correlation to Band-1, 3, and 5.Band-5: > 10 kHz, observed level decreases by approximately 20 dB until the median plane angle reaches approximately 120°.The general observation shows that while Band-2 has a negative correlation, its actual level change is relatively small, so it may be integrated into Band-1 and Band-3. Furthermore, Band-5 has a positive correlation with Band-1 and Band-3. In contrast, Band-4 has a negative correlation and its level change is significant. In addition, it can be noted that Band-4 includes various spectral cues as notches and peaks in the HRTFs. This means that these negative correlations can be caused by both notches and peaks. It should be noted however, that this correlation was done per HRTF (or per individual) and that the exact frequency delimitations for the five aggregated bands with their respective observed behavior varied across HRTFs. Further discussions concern the effects of peaks and notches in HRTFs based on previous experiments evaluating sound localization in the median plane using binaural representations. For these experiments, HRTFs were simplified; removing peaks and notches, while the levels of each aggregated frequency bands were averaged. Results showed that median plane sound localization remains possible, even without clearly present peaks and notches

Tone-2 tones discrimination task comparing audio and haptics

To investigating the capabilities of human beings to differentiate between tactile-vibratory stimuli with the same fundamental frequency but with different spectral content, this study concerns discrimination tasks comparing audio and haptic performances. Using an up-down 1 dB step adaptive procedure, the experimental protocol consists of measuring the discrimination threshold between a pure tone signal and a stimulus composed of two concurrent pure tones, changing the amplitude and frequency of the second tone. The task is performed employing exactly the same experimental apparatus (computer, AD-DA converters, amplifiers and drivers) for both audio and tactile modalities. The results show that it is indeed possible to discriminate between signals having the same fundamental frequency but different spectral content for both haptic and audio modalities, the latter being notably more sensitive. Furthermore, particular correlations have been found between the frequency of the second tone and the discrimination threshold values, for both audio and tactile modalities

CAVE-based Virtual Prototyping of an Audio Radiogoniometer: Ecological Validity Assesment

Presented at the 20th International Conference on Auditory Display (ICAD2014), June 22-25, 2014, New York, NY.This paper is part of a project concerned with the improvement of audio radiogoniometer design ergonomics and sound aesthetic. It introduces a virtual prototyping implementation of a simple radiogoniometer along with a methodology to assess its ecological validity. Said methodology involves a performance comparison between two different radiogoniometer designs, both implemented as virtual prototypes. While suggested assessment achievement supposes a companion study in a real environment (based on a physical prototype), significant results have already been gathered regarding the impact of the virtual environment on the virtual prototype validity

Survey and Implications for the Design of New 3D Audio Authoring Tools

International audience3D audio production tools vary from low-level programming libraries to higher-level user interfaces that are used across a wide range of applications. However, many of the user interfaces for authoring 3D audio parameters are underdeveloped, forcing users to resort to ad hoc solutions with other tools or programming languages. Identifying these limitations and custom methods are needed to inform the development of new user interfaces. Towards this end, an on-line survey was conducted with current practitioners to gather ethnographic information on their tools, methods, and opinions. Results of the survey revealed specific methods and limitations within authoring techniques and 3D audio production with regards to Audio Rendering and Recording, Visual Feedback, Functionality, and Workflow Integration. These results also shed light on three basic tasks that have to be performed interactively with 3D audio production tools: Defining the Rendering Space, Creation and Manipulation of Audio Objects, and Monitoring with Audio/Visual Feedback. This classification helps identifying the needs for 3D audio tools that address issues within the workflow and low-level functionality of systems

A Simple Explanation for DAMA with Moderate Channeling

We consider the possibility that the DAMA signal arises from channeled events in simple models where the dark matter interaction with nuclei is suppressed at small momenta. As with the standard WIMP, these models have two parameters (the dark matter mass and the size of the cross-section), without the need to introduce an additional energy threshold type of parameter. We find that they can be consistent with channeling fractions as low as about ~ 15%, so long as at least ~70% of the nuclear recoil energy for channeled events is deposited electronically. Given that there are reasons not to expect very large channeling fractions, these scenarios make the channeling explanation of DAMA much more compelling.Comment: 6 pages, 2 figure

Ecological correlates of risk and incidence of West Nile virus in the United States

West Nile virus, which was recently introduced to North America, is a mosquito-borne pathogen that infects a wide range of vertebrate hosts, including humans. Several species of birds appear to be the primary reservoir hosts, whereas other bird species, as well as other vertebrate species, can be infected but are less competent reservoirs. One hypothesis regarding the transmission dynamics of West Nile virus suggests that high bird diversity reduces West Nile virus transmission because mosquito blood-meals are distributed across a wide range of bird species, many of which have low reservoir competence. One mechanism by which this hypothesis can operate is that high-diversity bird communities might have lower community-competence, defined as the sum of the product of each species’ abundance and its reservoir competence index value. Additional hypotheses posit that West Nile virus transmission will be reduced when either: (1) abundance of mosquito vectors is low; or (2) human population density is low. We assessed these hypotheses at two spatial scales: a regional scale near Saint Louis, MO, and a national scale (continental USA). We found that prevalence of West Nile virus infection in mosquito vectors and in humans increased with decreasing bird diversity and with increasing reservoir competence of the bird community. Our results suggest that conservation of avian diversity might help ameliorate the current West Nile virus epidemic in the USA