Validation of a Screening Test of Auditory Function Using the Telephone

 

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Background: Several European countries have demonstrated successful use of telephone screening tests for auditory function. The screening test consists of spoken three-digit sequences presented in a noise background. The speech-to-noise ratios of the stimuli are determined by an adaptive tracking method that converges on the level required to achieve 50% correct recognition.

Purpose: A version of the three-digit telephone screening protocol for the United States was developed: the US National Hearing Test (NHT). The objective of the current study was to determine the sensitivity and specificity as well as the feasibility of the NHT for use within the Department of Veterans Affairs (VA).

Research Design and Study Sample: Using a multisite study design with convenience sampling, we used the NHT to collect data from 693 participants (1379 ears) from three geographical areas of the United States (Florida, Tennessee, and California).

Data Collection and Analysis: The NHT procedures were as follows: the participants (1) called a toll-free telephone number, (2) entered their assigned ear-specific identification code, (3) listened to 40-sets of digit triplets presented in speech-spectrum background noise, and (4) entered in the numbers that they heard on the telephone key pad. The NHT was performed on each ear, either at home or in a VA clinic. In addition to collecting data from the experimental task, we gathered demographic data and the data from other standard-of-care tests (i.e., audiometric thresholds and speech recognition tests in quiet and in noise).

Results: A total of 505 participants completed the NHT at a VA clinic, whereas 188 completed the test at home. Although the ear-specific NHT and mean pure-tone threshold all correlated significantly (p < 0.001), there were more modest correlations in the low- and high-frequency ranges with the highest correlation seen with the 2000 Hz mean pure-tone threshold. When the NHT 50% point or threshold was compared with the three-frequency PTA at 500, 1000, and 2000 Hz, the sensitivity was 0.87 and specificity was 0.54. When comparing the NHT with the four-frequency PTA at 500, 1000, 2000, and 4000 Hz, the sensitivity was 0.81 and specificity increased to 0.65. The NHT also correlated strongly with other speech-in-noise measures.

Conclusions: The NHT was found to correlate with other audiometric measures, including pure-tone thresholds and speech recognition tests in noise, at sufficiently high correlation values to support its use as a screening test of auditory function.