Effect of Tinnitus and Duration of Deafness on Sound Localization and Speech Recognition in Noise in Patients With Single-Sided Deafness

Abstract

Patients with single-sided deafness (SSD) often experience poor sound localization, reduced speech understanding in noise, reduced quality of life, and tinnitus. The present study aims to evaluate effects of tinnitus and duration of deafness on sound localization and speech recognition in noise by SSD subjects. Sound localization and speech recognition in noise were measured in 26 SSD and 10 normal-hearing (NH) subjects. Speech was always presented directly in front of the listener. Noise was presented to the deaf ear, in front of the listener, or to the better hearing ear. Tinnitus severity was measured using visual analog scale and Tinnitus Handicap Inventory. Relative to NH subjects, SSD subjects had significant deficits in sound localization and speech recognition in all listening conditions ( p < .001). For SSD subjects, speech recognition in noise was correlated with mean hearing thresholds in the better hearing ear ( p < .001) but not in the deaf ear. SSD subjects with tinnitus performed poorer in sound localization and speech recognition in noise than those without tinnitus. Shorter duration of deafness was associated with greater tinnitus and sound localization difficulty. Tinnitus visual analog scale and Tinnitus Handicap Inventory were highly correlated; the degree of tinnitus was negatively correlated with sound localization and speech recognition in noise. Those experiencing noticeable tinnitus may benefit more from cochlear implantation than those without; subjective tinnitus reduction may be correlated with improved sound localization and speech recognition in noise. Subjects with longer duration of deafness demonstrated better sound localization, suggesting long-term compensation for loss of binaural cues.

Keywords: duration of deafness; single-sided deafness; sound localization; speech recognition in noise; tinnitus.

Figure 1.

Hearing thresholds for single-sided deafness subjects, demonstrating both the better hearing (BH) ear and deaf ear.

Figure 2.

Boxplots of localization RMSE scores and SRTs in noise for the different spatial conditions as a function of subject groups (NH controls and SSD subjects). Top left, RMSE. Top right, SRTs for S₀N_DEAF condition. Bottom left, SRT for S₀N₀ condition. Bottom right, SRT for S₀N_BH condition. Boxes represent 25th and 75th percentiles, error bars represent 5th and 95th percentiles, circles denote outliers, solid lines show the median, and dashed lines show the mean. RMSE = root mean square error; SRT = speech reception threshold; NH = normal-hearing; SSD = single-sided deafness.

Figure 3.

Boxplots of localization RMSE scores and SRTs in noise for the different spatial conditions as a function of the presence or absence of tinnitus in SSD subjects. Top left, RMSE. Top right, SRTs for S₀N_DEAF condition. Bottom left, SRT for S₀N₀ condition. Bottom right, SRT for S₀N_BH condition. Boxes represent 25th and 75th percentiles, error bars represent 5th and 95th percentiles, circles denote outliers, solid lines show the median, and dashed lines show the mean. RMSE = root mean square error; SRT = speech reception thresholds.

Figure 4.

Boxplots of localization RMSE scores and SRTs in noise for the different spatial conditions in SSD subjects with “short” (<1 year) or “long” (>2 years) duration of deafness. Top left, RMSE. Top right, SRTs for S₀N_DEAF condition. Bottom left, SRT for S₀N₀ condition. Bottom right, SRT for S₀N_BH condition. Boxes represent 25th and 75th percentiles, error bars represent 5th and 95th percentiles, circles denote outliers, solid lines show the median, and dashed lines show the mean. RMSE = root mean square error; SRT = speech reception threshold.

Figure 5.

RMS error (first column) and SRTs in noise for the different spatial conditions (S₀N_SSD: second column; S₀N₀: third column; S₀N_BH: fourth column) as a function of THI scores (first row), VAS scores (second row), duration of deafness (third row), mean thresholds of the BH ear (fourth row), or deaf ear (fifth row). Open circles denote the individual data points, while the lines show the linear regression. The correlational coefficients and significance level were also displayed in each panel. RMS = root mean square; SRT = speech reception threshold; THI = Tinnitus Handicap Inventory; VAS = visual analog scale; BH = better hearing; SSD = single-sided deafness.