Simplified cochlear frequency selectivity assessment in normal-hearing and hearing-impaired listeners.

Objective: The ear's spectral resolution or frequency selectivity (FS) is a fundamental aspect of hearing but is not routinely measured in clinical practice. This study evaluated a simplified FS testing procedure for clinical use by replacing the time-consuming two-interval forced choice (2IFC) method with method of limits (MOL) carried out using a custom-made software and consumer-grade equipment.
Design and Study Sample: Study 1 compared the FS measure obtained with MOL and 2IFC procedure at two centre frequencies (CFs) (1 and 4 kHz) in 21 normal-hearing listeners. Study 2 determined the FS measure using MOL at five CFs (0.5-8 kHz) in 32 normal-hearing and nine sensorineural hearing loss listeners and compared them with their thresholds in quiet.
Results: FS measurements with MOL and 2IFC methods were highly correlated and had statistically comparable intra-subject test-retest reliability. FS measures determined with MOL were reduced in the hearing-impaired compared to normal-hearing listeners at the CF corresponding to their hearing loss. Linear regression analysis showed significant relationship between FS deterioration and quiet threshold loss ( p  < 0.0001, R ² = 0.56).
Conclusions: The simplified and affordable FS testing method can be used alongside audiometry to provide additional information about the cochlear function.