It is well-established that the smallest discrimination thresholds for interaural time differences (ITDs) are near 10 μs for normal hearing listeners. However, little is known about the hearing and training status of the test subjects from past studies. Previous studies also did not explicitly focus on the identification of the optimal stimulus and measurement technique to obtain the smallest threshold ITDs. Therefore, the first goal of the current study was to identify the stimulus and experimental method that maximizes ITD sensitivity. The second goal was to provide a precise threshold ITD reference value for both well-trained and un-trained normal hearing listeners using the optimal stimulus and method. The stimulus that yielded the lowest threshold ITD was Gaussian noise, band-pass filtered from 20 to 1400 Hz, presented at 70 dB sound pressure level. The best method was a two-interval procedure with an interstimulus interval of 50 ms. The average threshold ITD for this condition at the 75% correct level was 6.9 μs for nine trained listeners and 18.1 μs for 52 un-trained listeners.
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http://dx.doi.org/10.1121/1.5087566 | DOI Listing |
Int J Pediatr Otorhinolaryngol
January 2025
Department of Physical Therapy, Speech-Language Pathology and Occupational Therapy, Medical School, University of São Paulo, São Paulo, 05360-160, Brazil.
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 PDFProc Natl Acad Sci U S A
January 2025
Department of Communication Science and Disorders, University of Pittsburgh, Pittsburgh, PA 15213.
Neuropsychologia
December 2024
Stockholm University, Department of Psychology, Sweden.
In the search for the neural correlates of auditory consciousness, a candidate has been found using electroencephalography: the auditory awareness negativity (AAN). Earlier studies have investigated the AAN in response to lateralized sound. With headphones, there is a clear lateralization of AAN when two auditory lateralization cues are combined: the interaural level difference (ILD) and interaural time difference (ITD).
View Article and Find Full Text PDFNeuroscience
December 2024
School of Psychological and Cognitive Sciences, Peking University, Beijing 100080, China.
Prepulse inhibition (PPI) refers to the phenomenon in which a weak sensory stimulus before a strong one significantly reduces the startle reflex caused by the strong stimulus. Perceptual spatial separation, a phenomenon where auditory cues from the prepulse and background noise are distinguished in space, has been shown to enhance PPI. This study aims to investigate the neural modulation mechanisms of PPI by the spatial separation between the prepulse stimulus and background noise, particularly in the deep superior colliculus (deepSC).
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