Age-Related Changes in Interaural-Level-Difference-Based Across-Frequency Binaural Interference

Abstract

Low-frequency interaural time differences and high-frequency interaural level differences (ILDs) are used to localize sounds in the horizontal plane. Older listeners appear to be worse at horizontal-plane sound localization to compared younger listeners, but little is understood about age-related changes to across-frequency binaural processing. This study investigated if the frequency dependence of across-frequency ILD processing is altered for older compared to younger listeners, which was done by using an across-frequency binaural interference task (when the interaural difference sensitivity for a target sound is decreased by a spectrally remote interfering sound with zero interaural differences). It was hypothesized that as listeners experience advancing age and age-related high-frequency hearing loss (i.e., presbycusis), they will demonstrate worse binaural performance and experience more across-channel binaural interference (because of age-related temporal processing deficits), and will increasingly be affected by interferers at lower frequencies (because of age-related hearing loss) when compared to younger listeners. There were 11 older (>65 yrs) and 20 younger (<30 yrs) listeners with normal to near-normal audiometric thresholds up to 2 kHz. They were tested using a left-right ILD lateralization discrimination task. Single-tone ILD discrimination thresholds and across-frequency binaural interference were measured at 0.5, 1, 2, 4, and 8 kHz. ILD thresholds and interference were about twice as large for older compared to younger listeners. Interferers ≤1 kHz produced 2-3 times as much across-frequency binaural interference for older compared to younger listeners. Hearing thresholds were significant predictors of single-tone ILD thresholds; in addition, both target and interferer hearing thresholds were significant predictors of binaural interference. The results suggest a reweighting of binaural information that occurs with advancing age and age-related high-frequency hearing loss. This evidence of plasticity may help explain some of the age-related changes in spatial-hearing abilities.

Keywords: across-frequency binaural interference; aging; binaural hearing; hearing loss; interaural level differences (ILDs).

Figure 1

Individual (small points) and average (large points) audiometric thresholds in dB (re: hearing level, HL). Error bars represent ±1 standard error of the listener mean. Some points have error bars smaller than the size of the point. ONH, older normal hearing; YNH, younger normal hearing.

Figure 2

(A) Average ILD thresholds for single tones. Error bars represent ±1 standard error of the listener mean. (B) Individual ILD thresholds for single tones as a function of hearing threshold (θ_tar). f_tar, target frequency; ONH, older normal hearing; YNH, younger normal hearing; θ_tar, average interaural hearing threshold at the target frequency. The YNH data have been previously reported. Reproduced from Beth Rosen and Matthew J. Goupell, “The effect of target and interferer frequency on across-frequency binaural interference of interaural-level-difference sensitivity,” J. Acoust. Soc. Am. 151, 924–938 (2022), https://aip.scitation.org/doi/10.1121/10.0009398, with the permission of Acoustical Society of America.

Figure 3

Average ILD discrimination thresholds for target-interferer pairs are shown by data points for YNH (left column) and ONH (right column) listeners. Different rows represent different f[^int]. Error bars on each point represent ±1 standard error of the listener mean. The shaded areas represent the average ±1 standard error for the single-tone conditions, which were copied from Figure 2. The vertical dashed lines show the border where low-frequency ITDs are particularly potent. f_int, interferer frequency; f_tar, target frequency; ONH, older normal hearing; YNH, younger normal hearing. The YNH data have been previously reported. Reproduced from Beth Rosen and Matthew J. Goupell, “The effect of target and interferer frequency on across-frequency binaural interference of interaural-level-difference sensitivity,” J. Acoust. Soc. Am. 151, 924–938 (2022), https://aip.scitation.org/doi/10.1121/10.0009398, with the permission of Acoustical Society of America.

Figure 4

The average amount of binaural interference for YNH (A) and ONH (B) listeners. The numbers in the boxes represent the binaural interference index for target and interferer frequency combinations in dB. The numbers outside of the main grid are the average of each column and row. The overall average interference across all conditions is shown by the number in the top right box of each panel. Cells highlighted by red diagonal lines denote a relatively large amount of binaural interference, defined as at least 50% greater than the overall average. Cells highlighted by blue crossed lines denote a relatively small amount of binaural interference, defined as at least 50% less than average. The solid horizontal and vertical lines between 1 and 2 kHz show the border where low-frequency ITDs are particularly potent. f_int, interferer frequency; f_tar, target frequency; ONH, older normal hearing; YNH, younger normal hearing. The YNH data have been previously reported. Reproduced from Beth Rosen and Matthew J. Goupell, “The effect of target and interferer frequency on across-frequency binaural interference of interaural-level-difference sensitivity,” J. Acoust. Soc. Am. 151, 924–938 (2022), https://aip.scitation.org/doi/10.1121/10.0009398, with the permission of Acoustical Society of America.