Development and validation of a digits-in-noise hearing test in Persian

The prevalence of unrecognised and late-diagnosed hearing loss is higher in low- and middle-income than in high-income countries, due in part to lack of access to hearing services. Because hearing screening is important for early identification of hearing loss, development of an accessible, self-screening test that can detect hearing loss reliably and quickly would provide significant benefits, especially for underserved populations. This study aimed to develop and validate a new version of the digits-in-noise (DIN) test for Persian speaking countries.

Recordings of Persian digits 0-9 were binaurally presented in broadband speech-shaped noise. Using fitted speech intelligibility functions, digits were homogenised to achieve equal perceptual difficulty across stimuli. The evaluation was established by reference to existing English DIN tests.

Thirty Persian speaking young adults with normal hearing thresholds (≤20 dB HL, 0.25-8 kHz).

Speech intelligibility functions produced a mean speech reception threshold (SRT) of -7.7 dB, corresponding closely to previously developed DIN tests. There was no significant difference between test and retest SRTs, indicating high reliability of the test. Our findings suggest that language-specific factors need to be considered for cross-language comparison of DIN-SRTs.

This study introduces a convenient tool for future hearing screening in Persian speaking countries with limited access to audiology services.