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

Background and Objectives: 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 Methods: 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.Results: 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.Conclusions: 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.