Precision Of Sound Localization Research Articles

Predicting the Influence of Axon Myelination on Sound Localization Precision Using a Spiking Neural Network Model of Auditory Brainstem.

Spatial hearing allows animals to rapidly detect and localize auditory events in the surrounding environment. The auditory brainstem plays a central role in processing and extracting binaural spatial cues through microsecond-precise binaural integration, especially for detecting interaural time differences (ITDs) of low-frequency sounds at the medial superior olive (MSO). A series of mechanisms exist in the underlying neural circuits for preserving accurate action potential timing across multiple fibers, synapses and nuclei along this pathway. One of these is the myelination of afferent fibers that ensures reliable and temporally precise action potential propagation in the axon. There are several reports of fine-tuned myelination patterns in the MSO circuit, but how specifically myelination influences the precision of sound localization remains incompletely understood. Here we present a spiking neural network (SNN) model of the Mongolian gerbil auditory brainstem with myelinated axons to investigate whether different axon myelination thicknesses alter the sound localization process. Our model demonstrates that axon myelin thickness along the contralateral pathways can substantially modulate ITD detection. Furthermore, optimal ITD sensitivity is reached when the MSO receives contralateral inhibition via thicker myelinated axons compared to contralateral excitation, a result that is consistent with previously reported experimental observations. Our results suggest specific roles of axon myelination for extracting temporal dynamics in ITD decoding, especially in the pathway of the contralateral inhibition.

Sound Localization for Ad-Hoc Microphone Arrays

Sound localization is a field of signal processing that deals with identifying the origin of a detected sound signal. This involves determining the direction and distance of the source of the sound. Some useful applications of this phenomenon exists in speech enhancement, communication, radars and in the medical field as well. The experimental arrangement requires the use of microphone arrays which record the sound signal. Some methods involve using ad-hoc arrays of microphones because of their demonstrated advantages over other arrays. In this research project, the existing sound localization methods have been explored to analyze the advantages and disadvantages of each method. A novel sound localization routine has been formulated which uses both the direction of arrival (DOA) of the sound signal along with the location estimation in three-dimensional space to precisely locate a sound source. The experimental arrangement consists of four microphones and a single sound source. Previously, sound source has been localized using six or more microphones. The precision of sound localization has been demonstrated to increase with the use of more microphones. In this research, however, we minimized the use of microphones to reduce the complexity of the algorithm and the computation time as well. The method results in novelty in the field of sound source localization by using less resources and providing results that are at par with the more complex methods requiring more microphones and additional tools to locate the sound source. The average accuracy of the system is found to be 96.77% with an error factor of 3.8%.

Comment on "Differential Effects of the Temporal and Spatial Distribution of Audiovisual Stimuli on Cross-Modal Spatial Recalibration".

Bruns et al. (2020) provide new research that suggests that the ventriloquism after‐effect (VAE: an enduring shift of the perceived location of a sound toward a previously seen visual stimulus) and multisensory enhancement (ME: an improvement in the precision of sound localization) may dissociate depending on the rate at which exposure stimuli are presented. They reported that the VAE, but not the ME, was diminished when exposure stimuli were presented at 10 Hz rather than at 2 Hz. To the authors, this suggested that different neural structures underlie the VAE and ME. In our view, however, this needs to be tested more extensively because alternative and simpler explanations have not yet been checked.

Novel sound logger system for sound source localization using global navigation satellite system

Accurate sound localization is a very important technology to solve noise problem in the association with air plane, railroad, or wind-power generation and so on. In order to localize the sound source, direction of arrival (DOA) estimations in a couple of positions at a distance of several hundred meters are required. Generally, the measurement start timing is synchronized in each estimation position using 1PPS time signal from the global navigation satellite systems (GNSSs). However, the slight deviation in each measuring instrument occurs at the start time. Because the sampling clock of ADC (analog digital converter) is not synchronized. Therefore, the authors propose the application of time synchronization signal obtained from GNSS module to a sampling clock on an acoustic measurement in a wide range. Current some GNSS modules provide a pulse multiplied by 1PPS, which we call a time-synchronization signal. For the purpose, the authors have developed a logger apparatus which consists of a microphone amplifier, a GNSS, and an ADC module. The developed logger apparatuses are employed to perform sound source localization experiment in the field. As a result, the precision of sound localization within 2 meters is achieved successfully when the microphone sets at a distance of 10 m.

Improvement of sound source localization abilities in patients bilaterally supplied with active middle ear implants

Conclusions: Patients, who are bilaterally supplied with active middle ear implants, perform slightly better in sound localization tasks than when unilaterally aided or unaided. Objectives: To investigate the impact of bilateral use of active middle ear implants on sound source localization in the horizontal plane in patients with a sloping moderate-to-severe hearing loss. Methods: Ten adults supplied with Med-EL Vibrant Soundbridge systems (VSB) in both ears participated in the study. Four listening conditions were tested: unaided, aided with VSB on left or right ear and on both sides. In each condition the subjects had to judge the direction of broadband noises delivered randomly across a semicircular array of 11 loudspeakers arranged in an anechoic chamber. Results: When unaided or bilaterally aided, the subjects localized on average 40% of the stimuli correct; when unilaterally aided (left or right), this rate dropped to 20–30% in either condition. Precision of sound localization was highest when bilaterally aided, i.e. the mean RMS angular error was 10°, and lowest when unilaterally aided, i.e. 15°. This is in line with bilateral hearing aid users, who show similar performance in sound localization tasks.

Sound localization precision under conditions of the precedence effect: Effects of azimuth and standard stimuli

Minimum audible angles (MAAs) were estimated for single noise bursts, and for burst pairs that satisfied the conditions of the precedence effect (that is, produced fused images). In one burst-pair condition, the bursts to be discriminated differed in lead location; in the other, they differed in lag location. Sounds were presented over loudspeakers. MAAs were lowest for single bursts, slightly higher for lead discrimination, and much higher for lag discrimination. Presence of a standard reference burst had no reliable effect on performance. The data are interpreted using a model of Shinn-Cunningham et al. [J. Acoust. Soc. Am. 93, 2923-2932 (1993)] in which discrimination of precedence-effect burst pairs is based on the lateral position of the auditory image, which is a weighted average of the positions of the leading and lagging bursts.