The digits-in-noise test: Assessing auditory speech recognition abilities in noise

Abstract

A speech-in-noise test which uses digit triplets in steady-state speech noise was developed. The test measures primarily the auditory, or bottom-up, speech recognition abilities in noise. Digit triplets were formed by concatenating single digits spoken by a male speaker. Level corrections were made to individual digits to create a set of homogeneous digit triplets with steep speech recognition functions. The test measures the speech reception threshold (SRT) in long-term average speech-spectrum noise via a 1-up, 1-down adaptive procedure with a measurement error of 0.7 dB. One training list is needed for naive listeners. No further learning effects were observed in 24 subsequent SRT measurements. The test was validated by comparing results on the test with results on the standard sentences-in-noise test. To avoid the confounding of hearing loss, age, and linguistic skills, these measurements were performed in normal-hearing subjects with simulated hearing loss. The signals were spectrally smeared and/or low-pass filtered at varying cutoff frequencies. After correction for measurement error the correlation coefficient between SRTs measured with both tests equaled 0.96. Finally, the feasibility of the test was approved in a study where reference SRT values were gathered in a representative set of 1386 listeners over 60 years of age.

Development and validation of a smartphone-based digits-in-noise hearing test in South African English

“…The level of the masking noise was equal to the average level of the digits without any silences (Smits et al, 2013).…”

“…Additionally, the users themselves can administer the speech-in-noise hearing screening test, the test is fully automated, and it can be conducted in a few minutes. Furthermore, the digits-triplet speech-in-noise hearing screening test is ecologically valid since it approximates everyday speech-in-noise environments and it has been demonstrated to be sensitive to detect hearing loss (Jansen et al, 2010;Smits et al, 2004;Zokoll et al, 2012;Smits et al, 2013).…”

“…In a country like South Africa where there are 11 official spoken languages, digit-triplets may be more suitable than standard words or sentences because they depend on low linguistic demands and use a "closed-set" pattern (Smits et al, 2013;STATSSA, 2011). In addition, numerous South Africans from different linguistic backgrounds use English numerals within their own African language (Branford & Claughton, 2002).…”

“…After mailing a questionnaire to the people who completed the test, Smits et al (2006) found that 50% of callers, who failed the screening test, obtained a diagnostic hearing test. After the National Hearing Test was developed, Smits et al (2013) also developed the digits-in-noise test (DIN). The DIN was developed for diagnostic speech-in-noise hearing testing to determine hearing loss for speech recognition in noise (Smits et al, 2013).…”

“…After the National Hearing Test was developed, Smits et al (2013) also developed the digits-in-noise test (DIN). The DIN was developed for diagnostic speech-in-noise hearing testing to determine hearing loss for speech recognition in noise (Smits et al, 2013).…”