The Directional Effects of Marker Frequencies on Across-Channel Temporal Gap-Detection Tasks: An Experimental Study.

INTRODUCTION: Gap detection tests are crucial clinical tools for identifying auditory processing disorders that result from abnormalities in the central auditory nervous system. These tests assess the ability to resolve temporal information in sounds, which aids in the diagnosis of auditory temporal processing issues. This study explores the directional effects of marker frequencies on gap detection tasks with respect to the conditions of long and short frequency disparity (separation). METHODS: We measured the gap detection thresholds (GDTs) using four across-channel narrowband noise conditions (1-2, 2-1, 1-4, and 4-1 kHz). A within-subject study design involved 29 healthy individuals with normal hearing. Stimuli were presented monaurally using headphones routed via a calibrated audiometer. RESULTS: The condition with long frequency disparity and a low leading frequency (1-4 kHz) exhibited higher GDTs compared to the other across-channel conditions. However, we did not observe this effect in the other condition with long frequency disparity and a high leading frequency (4-1 kHz), which did not show significant differences from the two conditions with short frequency disparity. CONCLUSION: The study findings suggest that the combined effects of the spectral characteristics of the gap markers, including frequency disparity and order of presentation, influence the temporal resolution ability of auditory gap detection. Clinicians evaluating a patient suspected to have central auditory disorders should recognize that the across-channel GDTs may not consistently increase as the frequency separation between the markers increases.

Across- and Within-Channel Gap Detection Thresholds Yielded by Two Different Test Applications.

BACKGROUND: Individuals with auditory processing disorders show some deficits with the temporal processing of auditory signals. Gap detection measurements are commonly used to assess temporal processing skills across different listening tasks. PURPOSE: The aim of this study was to compare the gap detection thresholds (GDTs) in across-channel (AC) and within-channel (WC) tasks by using two computer applications-Adaptive Tests of Temporal Resolution (ATTR) and Psycon. RESEARCH DESIGN: A within-subject study design. STUDY SAMPLE: Twenty-one young adults with normal hearing participated in the study. DATA COLLECTION AND ANALYSIS: Each participant's gap detection performance was assessed using the narrowband noise stimuli of the ATTR and Psycon applications. Four conditions were administered with 2 kHz as the leading frequency marker before the gap and 1 kHz as the trailing frequency marker after the gap for AC tasks, and with 2 kHz as both the leading and trailing frequency markers for WC tasks. RESULTS: The results showed lower GDTs for the WC tasks than the AC tasks. Also, the GDT values for the WC tasks were lower in the ATTR than Psycon; whereas the GDT values for the AC tasks were higher in the ATTR than Psycon. CONCLUSION: The differences noted in the obtained GDT values from the ATTR and Psycon applications may be attributed to subtle spectral differences in the stimuli of the two programs. The present study also indicates that because of the inherent differences in the stimuli generated by the different software, the normative values for GDTs may need to be established according to evaluation tools before drawing conclusions about clinical conditions.

Auditory temporal resolution in adaptive tasks. Gap detection investigation.

OBJECTIVES: To study auditory temporal resolution skills using adaptive auditory tasks designed with a computer-based experimental program, and to provide normative valuesfor gap detection thresholds (GDTs) of young listeners in 3 listening conditions. Methods:  The GDTs were established under 3 stimulus conditions: 1) broadband noise (BBN), 2) narrowband noise within-channel (NBN WC) using similar leading and trailing markers centered at 1.0 KHz, and 3) narrowband noise across-channel (NBN AC) with the leading marker centered at 2.0 KHz and the trailing marker centered at 1.0 KHz. In within-subjects design, the GDTs were obtained from 27 normal hearing young Saudi adults at Speech and Hearing Laboratories, Department of Rehabilitation Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia between April 2017 and April 2018. Results: The mean GDTs for the BBN condition was 3.19 millisecsond (msec), NBN WC was 14.53 msec, and NBN AC was 29.71 msec. Our findings for the GDTs measured in the 3 conditions were consistent with those of earlier investigations that used different instrumentations. Also, no correlations among the GDTs of the 3 stimulus conditions were found. Conclusion: The present study showed that experimental program is a reliable tool with clinical potential to estimate GDTs across different conditions. Also, the findings of no correlations in the GDTs across stimulus conditions suggest that different processes were involved in the perception of the temporal gap for different stimulus conditions.

Efficacy of Directional Microphones in Hearing Aids Equipped with Wireless Synchronization Technology.

OBJECTIVE: This study aimed to evaluate the use of directionality in hearing aids with wireless synchronization on localization and speech intelligibility in noise. MATERIALS AND METHODS: This study included 25 individuals with bilateral mild to moderate flat sensorineural hearing loss. For the localization experiment, eight loudspeakers (Genelec 8020B) arranged in a circle covering a 0-360° angle and the Cubase 6 software were used for presenting the stimulus. A car horn of 260 ms was presented from these loudspeakers, one at a time, randomly. The listener was instructed to point to the direction of the source. The degree of the localization error was obtained with and without directionality and wireless synchronization options. For speech perception in a noise experiment, signal to noise ratio-50 (SNR-50) was obtained using sentences played through a speaker at a fixed angle of 0°. A calibrated eight-talker speech babble was used as noise and the babble was routed either through 0°, 90°, 270° (through one speaker at a time) or through both 90° and 270° speakers. RESULTS: The results revealed that the conditions where both the wireless synchronization and directionality were activated resulted in a significantly better performance in both localization and speech perception in noise tasks. CONCLUSION: It can be concluded that the directionality in the wireless synchronization hearing aids coordinates with each other binaurally for better preservation of binaural cues, thus reducing the localization errors and improving speech perception in noise. The results of this study could be used to counsel and justify the selection of the directional wireless synchronization hearing aids.

Development of equally intelligible Telugu sentence-lists to test speech recognition in noise.

OBJECTIVE: To develop sentence lists in the Telugu language for the assessment of speech recognition threshold (SRT) in the presence of background noise through identification of the mean signal-to-noise ratio required to attain a 50% sentence recognition score (SRTn). DESIGN: This study was conducted in three phases. The first phase involved the selection and recording of Telugu sentences. In the second phase, 20 lists, each consisting of 10 sentences with equal intelligibility, were formulated using a numerical optimisation procedure. In the third phase, the SRTn of the developed lists was estimated using adaptive procedures on individuals with normal hearing. STUDY SAMPLE: A total of 68 native Telugu speakers with normal hearing participated in the study. Of these, 18 (including the speakers) performed on various subjective measures in first phase, 20 performed on sentence/word recognition in noise for second phase and 30 participated in the list equivalency procedures in third phase. RESULTS: In all, 15 lists of comparable difficulty were formulated as test material. The mean SRTn across these lists corresponded to -2.74 (SD = 0.21). CONCLUSIONS: The developed sentence lists provided a valid and reliable tool to measure SRTn in Telugu native speakers.