This study was designed to determine whether extended high-frequency audiometry was capable of better differentiating between participants with normal hearing who did or did not have subjective tinnitus.

A total of 96 study participants were enrolled: 36 patients with unilateral tinnitus, 28 patients with bilateral tinnitus and 32 volunteers as controls. All 96 participants exhibited normal audiometry findings and hearing thresholds. Extended high-frequency audiometry was used to evaluate these patients.

There were differences between the extended high-frequency hearing thresholds of affected and unaffected ears in those with unilateral tinnitus, and in the 20–29-year-old bilateral tinnitus group, at 11.2, 12.5 and 14 kHz. Unilateral tinnitus subgroups had higher extended high-frequency hearing thresholds than those in control subjects, at all extended high frequencies.

Extended high-frequency audiometry can offer additional information regarding the hearing status of patients with tinnitus who exhibit normal pure tone thresholds when analysed via conventional hearing thresholds.

To assess the correlation of serum prestin level and audiological findings in adults with idiopathic sudden sensorineural hearing loss.

Audiometry and serum prestin measurements were performed at study entry (T0), at day 14 (end of treatment, T1) and at day 30 (T2).

A total of 25 idiopathic sudden sensorineural hearing loss patients and 25 healthy adults were included. The geometric mean prestin level in the case and control groups at T0 was 227.7 pg/ml and 130.5 pg/ml, respectively. The geometric mean prestin level in the case group demonstrated a downward trend at T1 and T2 (214.0 pg/ml and 180.1 pg/ml, respectively; p < 0.001). Of 17 patients with high baseline prestin levels (over 150 pg/ml), prestin levels tended to decrease in 11 patients, and 5 of them (45.5 per cent) showed good recovery.

The prestin concentrations increased in two-thirds of patients with idiopathic sudden sensorineural hearing loss. Future work is recommended to determine the location of injury.