Automated screening for high-frequency hearing loss

Hearing loss at high frequencies produces perceptual difficulties and is often an early sign of a more general hearing loss. This study reports the development and validation of two new speech-based hearing screening tests in English that focus on detecting hearing loss at frequencies above 2000 Hz.

The Internet-delivered, speech-in noise tests used closed target-word sets of digit triplets or consonant-vowel-consonant (CVC) words presented against a speech-shaped noise masker. The digit triplet test uses the digits 0 to 9 (excluding the disyllabic 7), grouped in quasi-random triplets. The CVC test uses simple words (e.g., "cat") selected for the high-frequency spectral content of the consonants. During testing, triplets or CVC words were identified in an adaptive procedure to obtain the speech reception threshold (SRT) in noise. For these new, high-frequency (HF) tests, the noise was low-pass filtered to produce greater masking of the low-frequency speech components, increasing the sensitivity of the test for HF hearing loss. Individual test tokens (digits, CVCs) were first homogenized using a group of 10 normal-hearing (NH) listeners by equalizing intelligibility across tokens at several speech-in-noise levels. Both tests were then validated and standardized using groups of 24 NH listeners and 50 listeners with hearing impairment. Performance on the new high frequency digit triplet (HF-triplet) and CVC (HF-CVC) tests was compared with audiometric hearing loss, and with that on the unfiltered, broadband digit triplet test (BB-triplet) test, and the ASL (Adaptive Sentence Lists) speech-in-noise test.

The HF-triplet and HF-CVC test results (SRT) both correlated positively and highly with high-frequency audiometric hearing loss and with the ASL test. SRT for both tests as a function of high-frequency hearing loss increased at nearly three times the rate as that of the BB-triplet test. The intraindividual variability (SD) on the tests was about 2.1 (HF-triplet) and 1.7 (HF-CVC) times less than that for the BB-triplet test. The effect on the HF-triplet test of varying presentation method (professional or cheap headphones and loudspeakers) was small for the NH group and somewhat larger, but nonsignificant for the hearing-impaired group. Test repetition produced a moderate, significant learning effect for the first and second retests, but was small and nonsignificant for further retesting. The learning effect was about two times larger for the HF-CVC test than for the HF-triplet test. The sensitivity of both new tests for high-frequency hearing loss was similar, with an 87% true-positive and 7% false-positive ratio for detecting an average high-frequency hearing loss of 20 dB or more.

The new HF-triplet and HF-CVC tests provide a sensitive and accurate method for detecting high-frequency hearing loss. The tests may signal developing hearing impairment at an early stage. The HF-triplet is preferred over the HF-CVC test because of its smaller learning effect, smaller error rate, greater simplicity, and lower cultural dependency.