Test-Retest Reliability and Preliminary Validation of Smartphone-Based Threshold and Categorical loudness Measures in...

Reliable hearing assessment at home can improve accessibility and reduce dependence on in-clinic testing. To be viable, home-based procedures must provide accurate results within short measurement times and remain robust to factors such as ambient noise and variable user attention. In this proof-of-concept study with a limited sample size, we evaluated two such procedures-a Graded Response Bracketing method (GRaBr) for pure-tone threshold estimation and a reinforced adaptive categorical loudness scaling method (rACALOS) for loudness-growth assessment - using remote, smartphone-based testing, and compared their outcomes with those obtained inside the laboratory using established reference procedures. Fifteen young adults with normal hearing completed the tasks at home and in the laboratory. Test-retest reliability was assessed by repeating the home measurements within one week of the initial session. Ambient noise levels in home environments were also recorded. The intraclass correlation coefficients for GRaBr measured at home exceeded 0.75, indicating good test-retest reliability. Similarly, home-based rACALOS showed generally high reliability, with across-run biases below 5 dB at all frequencies; however, mean interquartile ranges reached up to 18.4 dB at some loudness categories. Remote GRaBr measurements showed small, non-significant deviations from laboratory audiometry (0.4 ± 7.1 dB); however, frequency-specific biases of approximately ±5 dB were observed at 250 Hz and 4 kHz, with root-mean-square errors ranging from 4.6 to 8.0 dB across frequencies. Compared with the in-lab ACALOS, remote rACALOS showed an overall bias of 3.38 ± 11.8 dB across loudness categories, with no significant overall effect of test environment. These findings suggest that smartphone-based pure-tone audiometry and loudness-scaling assessments provide accurate and reliable results when using these procedures at home, at least in normal-hearing young adults, who are experienced loudness raters, under suitable acoustic conditions with low ambient noise.