Extended High-Frequency Smartphone Audiometry: Validity and Reliability

Extended high-frequency (EHF) audiometry (8-16 kHz) has an important role in audiological assessments such as ototoxicity monitoring, and for speech recognition and localization. Accurate and reliable EHF testing with smartphone technologies has the potential to provide more affordable and accessible hearing-care services, especially in underserved contexts.

To determine the accuracy and test-retest reliability of EHF audiometry with a smartphone application, using calibrated headphones.

Air-conduction thresholds (8-16 kHz) and test-retest reproducibility, recorded with conventional audiometry (CA) and smartphone audiometry (SA), using audiometric (Sennheiser HDA 300 circumaural) and nonstandard audiometric (Sennheiser HD202 II supra-aural) headphones, were compared in a repeated-measures design.

A total of 61 participants (122 ears) were included in the study. Of these, 24 were adults attending a tuberculosis clinic (mean age = 36.8, standard deviation [SD] = 14.2 yr; 48% female) and 37 were adolescents and young adults recruited from a prospective students program (mean age = 17.6, SD = 3.2 yr; 76% female). Of these, 22.3% (n = 326) of EHF thresholds were ≥25 dB HL.

Threshold comparisons were made between CA and SA, with audiometric headphones and nonstandard audiometric headphones. A paired samples t-test was used for comparison of threshold correspondence between conventional and smartphone thresholds, and test-retest reproducibility of smartphone thresholds.

Conventional thresholds corresponded with smartphone thresholds at the lowest intensity (10 dB HL), using audiometric and nonstandard audiometric headphones in 59.4% and 57.6% of cases, respectively. Conventional thresholds (exceeding 10 dB HL) corresponded within 10 dB or less, with smartphone thresholds in 82.9% of cases using audiometric headphones and 84.1% of cases using nonstandard audiometric headphones. There was no significant difference between CA and SA, using audiometric headphones across all frequencies (p > 0.05). Test-retest comparison also showed no significant differences between conditions (p > 0.05). Smartphone test-retest thresholds corresponded within 10 dB or less in 86.7% and 93.4% of cases using audiometric and nonstandard audiometric headphones, respectively.

EHF smartphone testing with calibrated headphones can provide an accurate and reliable option for affordable mobile audiometry. The validity of EHF smartphone testing outside a sound booth as a cost-effective and readily available option to detect high-frequency hearing loss in community-based settings should be established.