Time delay estimation from HRTFs and HRIRs

2017 IEEE 3rd VR Workshop on Sonic Interactions for Virtual Environments (SIVE)

Sound in Virtual Reality (VR) has been explored in a variety of algorithms which try to enhance the illusion of presence, improving sound localization and spatialization in the virtual environment. As new systems are developed, different models are applied. There is still the need to evaluate and understand the main advantages of each of these approaches. In this study, a performance comparison of two methods for real-time 3D binaural sound tested preferences and quality of presence for headphones in a VR experience. Both the mathematical based HRTF and the convolution based measured HRTF from the MIT KEMAR show a general similarity in the participants sense of localization, depth and presence. Nevertheless, the tests also indicate a preference in elevation perception for the convolution-based measured HRTF. Further experiments with new tools, techniques, contexts, and guidelines are therefore required to highlight the importance and differences between these two methods and other implementations.

Acoustical Science and Technology, 2003

This paper proposes a new method for the interpolation of Head-Related Transfer Functions (HRTFs) applied to the generation of 3-D binaural sound, especially when dealing with moving sound sources indoors. The method combines a modified linear interpolation strategy with a representation of the auditory space based on spatial characteristic functions (SCFs), previously known from the literature. The main idea here is to associate the low complexity the SCF-based representation yields in the multi-source case with the inherent simplicity of the linear interpolation. Complexity issues are discussed. The performance of the proposed method is evaluated against the direct bilinear interpolation of HRTFs, using Spatial Frequency Response Surfaces (SFRSs).

The generation of virtual auditory space (VAS) requires that the sound presented, say over headphones, is filtered in a manner that replicates the normal filtering of the external auditory periphery (the "outer ears"). The sound pressure transformation from a point in space to the eardrum is referred to as the Head Related Transfer Function (HRTF). HRTFs are measures at discrete points in space, while space itself is continuous. We describe the acoustic and psychophysical errors associated with a method of HRTF interpolation that employs a spherical thin-plate spline. Errors in the reconstructed HRTFs were dependant on the number of the locations in the interpolation set and increased markedly for interpolation sets with less than 150 locations (sparse sets). Auditory localization performance began to deteriorate for interpolation sets with less than 150 locations and the localization errors principally followed the cone of confusion. These results indicate that high fidelity continuous VAS can be generated from HRTFs recorded at as few as 150 discrete locations.

2000

The generation of virtual auditory space (VAS) requires that the sound presented, say over headphones, is filtered in a manner that replicates the normal filtering of the external auditory periphery (the "outer ears"). The sound pressure transformation from a point in space to the eardrum is referred to as the Head Related Transfer Function (HRTF). HRTFs are measures at discrete points in space, while space itself is continuous. We describe the acoustic and psychophysical errors associated with a method of HRTF interpolation that employs a spherical thin-plate spline. Errors in the reconstructed HRTFs were dependant on the number of the locations in the interpolation set and increased markedly for interpolation sets with less than 150 locations (sparse sets). Auditory localization performance began to deteriorate for interpolation sets with less than 150 locations and the localization errors principally followed the cone of confusion. These results indicate that high fidelity continuous VAS can be generated from HRTFs recorded at as few as 150 discrete locations.

Accurate localization of sound in 3-0 space is based on variations in the spectrum of sound sources. These variations arise mainly from rejection and difiaction eflects caused by the pinnae and are described through a set of Head-Related Transfer Functions (HRTF's) that are unique for each aiimuth and elevation angle. A virtual sound source can be rendered in the desired location by filtering with the corresponding HRTF for each ea,: Previous work on HRTF modeling has mainly focused on methods that attempt to model each transfer function individually. These methods are generally computationally-complex and cannot be used for real-time spatial rendering of multiple moving sources. In this work we provide an alternative approach, which uses a multiple-input single-output state-space system to create a combined model of the HRTF's for all directions. This method exploits the similarities among the diflerent HRTF's to achieve a signifcant reduction in the model size with a minimum loss of accuracy.

Computer Music Journal, 1995

About the Cover Cylindrical Surface Plot of the Head-Related Transfer Function: Magnitude Response as a Function of Frequency over Azimuth Angle on a Radial Axis, by William Martens of E-mu/Creative Technology Center. The cover photograph shows a visualization of the magnitude response (gain) of the head-related transfer function (HRTF) measured at the eardrum position of the anthropomorphic mannequin KEMAR. HRTFs were measured for 19 loudspeaker directions circling the side of the head facing the loudspeaker placed at ear level. The surface was constructed by interpolating the gain within each of 50 log-spaced frequency bands for the 19 HRTFs using a bicubic spline. The lowest band was centered on 55 Hz, the highest on 21,331 Hz. The distance of the surface from the origin and the color indicates the gain at a particular frequency and azimuth, which ranges from blue-black at the lowest gain (-43.9 dB) to a desaturated yellow at the peak gain (14.6 dB).

Proceedings of 1995 Workshop on Applications of Signal Processing to Audio and Accoustics, 1995

In order to achieve realistic synthesized 3-dimensional acoustic fields over headphones, low-order approximations of head related transfer functions (HRTFs) are desirable not only because of the computational complexity reduction, but also because of the potential for allowing listeners to modify the low-order approximation parameters in order to generate interpolated HRTFs that optimize the source localization percept. By fitting the directional component of a HRTF, commonly known as the directional transfer function @TF) [l], it is possible to achieve low-order systems for the purpose of interpolating HRTFs even if the number of . parameters required to approximate the entire HRTF is relatively large.

Acoustical Science and Technology, 2012

2004

One of the fundamental limitations on the fidelity of interactive virtual audio display systems is the delay that occurs between the time a listener changes his or her head position and the the time the display changes its audio output to reflect the corresponding change in the relative location of the sound source. In this experiment, we examined the impact that six difference headtracker latency values (12, 20, 38, 73, 145 and 243 ms) had on the localization of broadband sound sources in the horizontal plane. In the first part of the experiment, listeners were allowed to take all the time they needed to point their heads in the direction of a continuous sound source and press a response switch. In the second part of the experiment, the stimuli were gated to one of eight different durations (64, 125, 250, 375, 500, 750, 1000 and 2000 ms) and the listeners were required to make their head-pointing responses within two seconds after the onset of the stimulus. In the openended respons...