Authors: Charles S. Watson1, Gary R. Kidd1, Daniel P. Maki1
1Communication Disorders Technology, Inc., and Indiana University, Bloomington, Indiana USA
Background: Telephone-administered tests for hearing loss have now been developed in many countries. The version introduced in the US in 2012, the US National Hearing Test (USNHT), has been administered to 150,000+ persons. This provides a substantial estimation of the distributions of pure-tone losses within populations who voluntarily take such a test.
Method: The USNHT is modeled after the digits-in-noise (DIN) procedures developed by Smits et al. (2004). Three-digit sequences were recorded, and a unique sample of speech-spectrum noise was combined with each sequence. The test was administered using an adaptive threshold-tracking procedure, to left and right ears independently. Audiograms and the USNHT were obtained for 1379 ears. Strong correlations between pure-tone loss and SNR threshold were then used to estimate losses from the USNHT alone. The test has now been taken by 150,000+ callers. Over 5000 persons who failed the test were contacted about actions taken to address their hearing problems.
Results: Callers were 67% men and 33% women. Mean PTA losses were approximately 29 dB HL for the better ears and 34 dB for the worse. About 78% of callers showed a significant loss in at least one ear. PTA means were 32 dB (men) and 31 dB (women). Average total call duration was about 12 minutes. Although only 11% of the follow-up surveys were completed (500+), 38% had taken action or planned to do so.
Conclusion: Large numbers of persons who suspect they may have hearing loss will elect to take a telephone-administered screening test if it is offered without a fee, and with some assurance that the test is valid and the results will remain private. The results confirm the value of DIN testing by telephone in increasing knowledge of hearing health and encouraging people to take action to address their hearing problems.