Human sound localization abilities rely on binaural and spectral cues. Spectral cues arise from interactions between the sound wave and the listener's body (head-related transfer function, HRTF). Large individual differences were reported in localization abilities, even in young normal-hearing adults. Several studies have attempted to determine whether localization abilities depend mostly on acoustical cues or on perceptual processes involved in the analysis of these cues. These studies have yielded inconsistent findings, which could result from methodological issues. In this study, we measured sound localization performance with normal and modified acoustical cues (i.e., with individual and non-individual HRTFs, respectively) in 20 naïve listeners. Test conditions were chosen to address most methodological issues from past studies. Procedural training was provided prior to sound localization tests. The results showed no direct relationship between behavioral results and an acoustical metrics (spectral-shape prominence of individual HRTFs). Despite uncertainties due to technical issues with the normalization of the HRTFs, large acoustical differences between individual and non-individual HRTFs appeared to be needed to produce behavioral effects. A subset of 15 listeners then trained in the sound localization task with individual HRTFs. Training included either visual correct-answer feedback (for the test group) or no feedback (for the control group), and was assumed to elicit perceptual learning for the test group only. Few listeners from the control group, but most listeners from the test group, showed significant training-induced learning. For the test group, learning was related to pre-training performance (i.e., the poorer the pre-training performance, the greater the learning amount) and was retained after 1 month. The results are interpreted as being in favor of a larger contribution of perceptual factors than of acoustical factors to sound localization abilities with virtual sources.
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http://dx.doi.org/10.3389/fnins.2014.00451 | DOI Listing |
Growing numbers of children and adults who are deaf are eligible to receive cochlear implants (CI), which provide access to everyday sound. CIs in both ears (bilateral CIs or BiCIs) are becoming standard of care in many countries. However, their effectiveness is limited because they do not adequately restore the acoustic cues essential for sound localization, particularly interaural time differences (ITDs) at low frequencies.
View Article and Find Full Text PDFJ Hist Neurosci
January 2025
Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.
The story of David Ferrier's demonstration at the International Medical Congress in London in August 1881 of a monkey experimentally rendered hemiplegic by a focal surgical brain lesion-prompting Charcot's observation, "C'est un malade!"-is well known as a seminal event in the history of the localization of functions in the cerebral cortex. Less well known is the fact that, on the same occasion, Ferrier demonstrated a second monkey, known as monkey F, apparently deaf as a consequence of bilateral temporo-sphenoidal brain lesions. The purpose of this article is, first, to give a chronological account of this demonstration and subsequent related events, including Ferrier's trial under the Vivisection Act, the publication of the pathological findings in the animal's brain, the dispute about the localization of the "auditory centre" with Edward Schäfer, and the first glimmerings of human homologues of cortical deafness.
View Article and Find Full Text PDFJ Vis Exp
December 2024
Department of Otolaryngology, Head and Neck Surgery, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health;
Single-sided deafness (SSD), where there is severe to profound hearing loss in one ear and normal hearing in the other, is a prevalent auditory condition that significantly impacts the quality of life for those affected. The ability to accurately localize sound sources is crucial for various everyday activities, including speech communication and environmental awareness. In recent years, bone conduction intervention has emerged as a promising solution for patients with SSD, offering a non-invasive alternative to traditional air conduction hearing aids.
View Article and Find Full Text PDFJ Morphol
January 2025
Department of Zoology, Denver Museum of Nature & Science, Denver, Colorado, USA.
The barn owl is a common research subject in auditory science due to its exceptional capacity for high frequency hearing and superb sound source localization capabilities. Despite longstanding interest in the auditory performance of barn owls, the function of its middle ear has attracted remarkably little attention. Here, we report the middle ear transfer function measured by laser Doppler vibrometry and direct measurements of inner ear pressures.
View Article and Find Full Text PDFJ Otol
July 2024
Department of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, 100853, China.
Purpose: To analyze the effect of right versus left long-term single-sided deafness (SSD) on sound source localization (SSL), discuss the necessity of intervention and treatment for SSD patients, and analyze the therapeutic effect of long-term unilateral cochlear implantation (UCI) from the perspective of SSL.
Methods: This study included 25 patients with SSD, 11 patients with UCI, and 30 participants with normal hearing (NH). Their SSL ability was tested by obtaining their average root mean square (RMS) error values of SSL test.
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