Measurement of Loudness Discomfort Levels as a Test for Hyperacusis: Test-Retest Reliability and Its Clinical Value

Abstract

Objectives: The aims of this study were to investigate the test-retest reliability of measurements of loudness discomfort levels (LDLs), to suggest cut-off values for diagnosing patients with hyperacusis, and to evaluate the clinical value of-LDL measurements as a test for monitoring hyperacusis.

Methods: For the test-retest reliability of LDL measurements (study 1), a total of 68 patients who sought consultations at our clinic were subcategorized into four groups: patients with tinnitus (group 1), tinnitus and hearing loss (group 2), hyperacusis (group 3), and normal controls (group 4). Inter-hour and inter-day test-retest reliability values using different stimuli were investigated. For study 2, the clinical value of LDL measurements using pure tone stimuli was analyzed by comparing changes after sound generator use in patients with hyperacusis.

Results: In study 1, the group 3 patients showed significantly lower LDLs than the other groups. High test-retest reliability of LDL tests was demonstrated, regardless of the type of stimulus used. The cut-off values for screening patients with hyperacusis were 90 dB HL using pure tone stimuli and 62 dB HL using white-band noise stimuli. In study 2, significantly increased LDLs were correlated with improved symptoms and improved scores on tinnitus questionnaires after sound generator use, indicating that LDL measurement is a reliable test for monitoring hyperacusis during an intervention.

Conclusion: LDL measurement is a reliable diagnostic tool to reflect the condition of hyperacusis, especially during the course of treatment.

Keywords: Hyperacusis; Loudness Perception; Sound Generator.

Fig. 1.

Mean loudness discomfort levels (LDLs) using pure tone stimuli at different frequencies, showing that the patients in group 3 had lower mean LDLs (74 dB; standard deviation [SD], 2.96). Group 1 (n=15): patients with tinnitus; group 2 (n=12): patients with tinnitus and hearing loss; group 3 (n=21): patients with hyperacusis; group 4 (n=20): normal control. ^*P<0.05. Error bars indicate SDs. Tests of the hypotheses were assessed using the t-test for six independent groups per frequency with a Bonferroni-adjusted alpha level of 0.008 per test (0.05/6).

Fig. 2.

Mean loudness discomfort levels (LDLs) using white-band noise, showing that group 3 patients had statistically significantly lower mean LDL values, at 45.1 dB HL (standard deviation [SD], 12.1 dB HL, P<0.01. Group 1 (n=15): patients with tinnitus; group 2 (n=12): patients with tinnitus and hearing loss; group 3 (n=21): patients with hyperacusis; and group 4 (n=20): normal control patients. ^*P<0.05. Error bars indicate SDs. Tests of the hypotheses were assessed using the t-test for six independent groups with a Bonferroni adjusted alpha level of 0.008 per test (0.05/6).

Fig. 3.

Inter-hour and inter-day reliability coefficients of loudness discomfort level measurements using pure-tone stimuli (r=0.8–0.93).

Fig. 4.

Comparison of hyperacusis symptoms and loudness discomfort level (LDL) measurements in group 2 patients. Significantly increased LDLs and decreased symptoms of hyperacusis were observed in the tinnitus patients with hyperacusis after 6 months of sound generator (SG) use (^*P=0.02).

Fig. 5.

Correlations between mean loudness discomfort level (LDL) values and patients’ scores on the Tinnitus Handicap Inventory (THI). Scatter plot of pre-post changes in the THI versus pre-post changes in LDLs, showing that a larger decrease in THI scores was correlated with a larger increase in LDLs (r=0.73, P<0.05).