Normative Data and Repeatability of a 4-kHz Pure-Tone Psychoacoustic Tuning Curve Using a Single Clinical Audiometer

This study aimed to establish normative data and evaluate the test-retest variability of 4 kHz pure-tone psychoacoustic tuning curves (PTCs) measured using a conventional two-channel clinical audiometer. Materials and.

Thirty-four adults with normal hearing (≤25 dB HL) underwent two PTC testing sessions separated by a 2-week interval. A 4,000-Hz signal tone presented at 10 dB above threshold and seven pure-tone maskers (3,150-4,896 Hz) were administered using an Interacoustics AC40 Audiometer through the 3-down/1-up approach. Participants were randomly assigned to either low-to-high or high-to-low masker-frequency-order groups. Test-retest variability was analyzed across masker frequencies, and correlations with participant demographics were determined. Q10 values were evaluated as indices of frequency selectivity.

All participants completed the testing without auditory discomfort. Approximately 80% had a test-retest variability of ≤8 dB, indicating high reliability. The largest intersession differences were observed at 4,896 Hz (9.80±7.35 dB) and 3,150 Hz (5.77±6.95 dB). Test-retest variability was positively correlated with age (r= 0.50, p=0.006). The mean Q10 was 5.76±1.72, and decreased significantly with age (r=-0.49, p=0.014). The average tuning curve exhibited a V-shaped pattern with a tip at 4,000 Hz, consistent with classical findings.

The simplified pure-tone PTC protocol using a standard clinical audiometer provided reproducible and relevant estimates of auditory frequency selectivity. These findings support its clinical feasibility for assessing frequency selectivity and age-related changes in the auditory filter.