Measurements of auditory navigation in virtual acoustic space

IEEE Journal of Selected Topics in Signal Processing, 2015

Virtual auditory displays are systems that use signal processing techniques to manipulate the apparent spatial locations of sounds when they are presented to listeners over headphones. When the virtual audio display is limited to the presentation of stationary sounds at a finite number of source locations, it is possible to produce virtual sounds that are essentially indistinguishable from sounds presented by real loudspeakers in the free field. However, when the display is required to reproduce sound sources at arbitrary locations and respond in real-time to the head motions of the listener, it becomes much more difficult to maintain localization performance that is equivalent to the free field. The purpose of this paper is to present the results of a study that used a virtual synthesis technique to produce head-tracked virtual sounds that were comparable in terms of localization performance with real sound sources. The technique made use of an in-situ measurement and reproduction technique that made it possible to switch between the head-related transfer function measurement and the psychoacoustic validation without removing the headset from the listener. The results demonstrate the feasibility of using head-tracked virtual auditory displays to generate both short and long virtual sounds with localization performance comparable to what can be achieved in the free field.

Frontiers in Neuroscience, 2014

Sound localization studies over the past century have predominantly been concerned with directional accuracy for far-field sources. Few studies have examined the condition of near-field sources and distance perception. The current study concerns localization and pointing accuracy by examining source positions in the peripersonal space, specifically those associated with a typical tabletop surface. Accuracy is studied with respect to the reporting hand (dominant or secondary) for auditory sources. Results show no effect on the reporting hand with azimuthal errors increasing equally for the most extreme source positions. Distance errors show a consistent compression toward the center of the reporting area. A second evaluation is carried out comparing auditory and visual stimuli to examine any bias in reporting protocol or biomechanical difficulties. No common bias error was observed between auditory and visual stimuli indicating that reporting errors were not due to biomechanical limitations in the pointing task. A final evaluation compares real auditory sources and anechoic condition virtual sources created using binaural rendering. Results showed increased azimuthal errors, with virtual source positions being consistently overestimated to more lateral positions, while no significant distance perception was observed, indicating a deficiency in the binaural rendering condition relative to the real stimuli situation. Various potential reasons for this discrepancy are discussed with several proposals for improving distance perception in peripersonal virtual environments.

Archives of Acoustics, 2015

The paper demonstrates that blind people localize sounds more accurately than sighted people by using monaural and/or binaural cues.In the experiment, blind people participated in two tests; the first one took place in the laboratory and the second one in the real environment under different noise conditions. A simple click sound was employed and processed with non-individual head related transfer functions. The sounds were delivered by a system with a maximum azimuth of 32° to the left side and 32° to the right side of the participant’s head at a distance ranging from 0.3 m up to 5 m.The present paper describes the experimental methods and results of virtual sound localization by blind people through the use of a simple electronic travel aid based on an infrared laser pulse and the time of flight distance measurement principle. The lack of vision is often compensated by other perceptual abilities, such as the tactile or hearing ability.The results show that blind people easily perc...

Acta Physica Polonica A, 2013

The study was undertaken to check the eect of 3D sound recording and reproduction methods on performance in localization of sound source by the visually impaired and normally sighted subjects. The performance was evaluated on the basis of the ability to identify the direction from which the sound comes and the direction of its propagation. The experiment involved a test in which the subjects were exposed to sounds reproduced by two methods of spatial reproduction: binaural (headphones) and Ambisonics (loudspeaker). The binaural recordings were reproduced through two types of headphones, open and closed ones, and the recordings were made with the help of a dummy head. The recordings for loudspeaker reproduction were made with the use of two microphone matrices, Octava and Panasonic. The subjects were adults and children, including blind and VIC. They had otologically normal hearing. The test included realization of three tasks. The rst concerned identication of the direction from which sound has come from an immovable source, a rattle or a drum. In the second and third task, the subjects were asked to indicate the direction of motion of the source of sound (vehicle). For the adults, the method of recording and reproduction of sound had little eect on the test results. For the VIC, a signicant dierence was noted between the results of headphone and loudspeaker exposure, to the advantage of the headphone exposure. The method of binaural recording and sound exposure through headphones seems much more eective for auditory training of VIC.

The paper summarizes a number of audio-related studies conducted by the Sound of Vision consortium, which focuses on the construction of a new prototype electronic travel aid for the blind. Different solutions for spatial audio were compared by testing sound localization accuracy in a number of setups, comparing plain stereo panning with generic and individual HRTFs, as well as testing different types of stereo headphones vs custom designed quadrophonic proximaural headphones. A number of proposed sonification approaches were tested by sighted and blind volunteers for accuracy and efficiency in representing simple virtual environments.

An acoustic image of space is an acoustically described visual image intended to help blind people orient themselves in space. Description is made with the aid of spatial sounds created using HRTF filters. HRTF filters are empirically acquired FIR filter sets that describe changes to the sound as it travels from its source towards the human eardrum. They include changes related to body shape, ears, ear canal, etc. Our research focused on finding the maximum resolution of the human auditory system when determining the location of a sound source in space. This is also the maximum resolution for creating an acoustic image. We were interested in minimum azimuth and elevation change resolution -we tried to establish the minimum angle between two sources that could still be detected. Resolution dependence on signal bandwidth was also measured. The results were encouraging, especially in the horizontal plane, where most of subjects were able to tell the difference between two sources only 5° apart. Edge resolution, with 80° -90° azimuth, was still satisfactory if a wide bandwidth signal was used. If elevation is increased, the resolution deteriorates quickly and is no longer satisfactory. To address this problem, different coding should be used to create an acoustic image of elevation.

2005

Listening tests were carried out for investigating the localization performance of 42 untrained subjects using noise stimuli in a 2D virtual acoustic display (VAD). Measurements were made on the basis of the former GUIB project (Graphical User Interface for Blind Persons). Results of the evaluation of the average spatial resolution will be presented. Suggestions for optimal partitioning the virtual space is made on a rectangle 2D VAD in front of the listener, focusing on vertical localization.

Proceedings of the 13th International Conference on Disability, Virtual Reality and Associated Technologies (ICDV 2021), 2021

Prior research reveals that spatial navigation skills rely mostly in visual sensory abilities, but the study of how spatial processing operates in the absence of visual information is still incomplete. Therefore, a spatial navigation task in virtual reality using auditory cues was developed to study navigational strategies in blindfolded sighted individuals. Twenty healthy adult participants were recruited. The task consisted of a VR scene, in which participants were asked to localize a sound source and move to the target without visual information throughout the entire task. Task difficulty was manipulated by route length and complexity in three different difficulty levels repeated in two different trials. The first trial (learning) consisted of moving to the sound source and then returning to the starting point. The second trial (retrieval) consisted of the same task without the sound source but with auditory cues from obstacles to test spatial learning. Performance was assessed from behavioral measures of execution time, obstacle collisions, and prompts during the task execution. These variables were compared to established neuropsychological instruments for global cognition (Montreal Cognitive Assessment) and memory abilities (Wechsler Memory Scale-R). The results suggested that difficulty level affected navigation performance in both trials. Navigation performance was better in the retrieval trial, but both learning and retrieval trials were explained by global cognitive functioning. These data suggested the Soundspace VR as being effective to study spatial navigation in the absence of visual information and highlight the importance of auditory information from spatial sound cues for spatial navigation and spatial learning.

IEEE SMC'99 Conference Proceedings. 1999 IEEE International Conference on Systems, Man, and Cybernetics (Cat. No.99CH37028), 1999

In space perception, the straight lines running phenomenally parallel to the median plane and straight lines running phenomenally equi-distant from the median plane are called parallel alley and equi-distance alley, respectively. It is known that these lines are concave bending towards the median plane in binocular visual space. Using virtual environmental display system, it became possible to construct the experimental system to measure the parallel alley and the eqi-distance alley in binaural auditory space. The experiments were conducted and the results were obtained as follows: (1) Parallel alley and eqi-distance alley in auditory space are not always straight in physical sense, and the forms of them depend on the distance from the median plane. (2) Parallel alley lies inside eqi-distance alley. Employing sound intensity and binaural time differences as parameters, mathematical models were constructed to explain the auditory alleys. By simulation, it was confirmed that the models successfully explain the experimental results obtained in virtual environmental system.

2012