Development of the Mandarin Digit-in-Noise Test and Examination of the Effect of the Number of Digits Used in the Test

Abstract

Objectives: The study aimed to develop and validate the Mandarin digit-in-noise (DIN) test using four digit (i.e., two-, three-, four-, and five-digit) sequences. Test-retest reliability and criterion validity were evaluated. How the number of digits affected the results was examined. The research might lead to more informed choice of DIN tests for populations with specific cognitive needs such as memory impairment. Design: The International Collegium of Rehabilitative Audiology guideline for developing the DIN was adapted to create test materials. The test-retest reliability and psychometric function of each digit sequence were determined among young normal-hearing adults. The criterion validity of each digit sequence was determined by comparing the measured performance of older adult hearing aid users with that obtained from two other well-established sentence-in-noise tests: the Mandarin hearing-in-noise test and the Mandarin Chinese matrix test. The relation between the speech reception thresholds (SRTs) of each digit sequence of the DIN test and working memory capacity measured using the digit span test and the reading span test were explored among older adult hearing aid users. Together, the study sample consisted of 54 young normal-hearing adults and 56 older adult hearing aid users. Results: The slopes associated with the two-, three-, four-, and five-digit DIN test were 16.58, 18.79, 20.42, and 21.09 %/dB, respectively, and the mean SRTs were −11.11, −10.99, −10.56, and −10.02 dB SNR, respectively. Test-retest SRTs did not differ by more than 0.74 dB across all digit sequences, suggesting good test-retest reliability. Spearman rank-order correlation coefficients between SRTs obtained using the DIN across the four digit (i.e., two-, three-, four-, and five-digit) sequences and the two sentence-in-noise tests were uniformly high (r s = 0.9) across all participants, when data from all participants were considered. Results from the digit span test and reading span test correlated significantly with the results of the five-digit sequences (r s = −0.37 and −0.42, respectively) but not with the results of the two-, three-, and four-digit sequences among older hearing aid users. Conclusions: While the three-digit sequence was found to be appropriate for clinical use for assessment of auditory perception, the two-digit sequence could be used for hearing screening. The five-digit sequence could be difficult for older hearing aid users, and with its SRT related to working memory capacity, its use in the evaluation of speech perception should be investigated further. The Mandarin DIN test was found to be reliable, and the findings are in line with SRTs obtained using standardized sentence tests, suggesting good criterion validity.

An Exploration of the Memory Performance in Older Adult Hearing Aid Users on the Integrated Digit-in-Noise Test

“…However, in Wang and Wong (2023) , while a significant correlation was observed between the five-digit SRT and the WM test, the difference in SRTs between the five-digit and other digit sequences was not substantial. The potential reason for this could be that the variability in participants’ WM capacity was limited, with the majority exhibiting relatively normal levels of WM function.…”

“…Building upon the three-digit DIN framework, we developed the iDIN, which utilizes sequences of two-, three-, four-, and five-digit sequences ( Wang & Wong, 2023 ). Similar to the DIN, shorter digit sequences in the iDIN, such as two-digit and three-digit, predominantly measure speech perception in noise ability.…”

“…Our research indicated that the SRTs of the iDIN exhibited a slight increase as the length of the sequences increased, and the difference in SRTs between two-digit and five-digit sequences was 1.09 dB SNR for young adults and 1.69 dB SNR for older HA users. A significant correlation was observed exclusively between the five-digit SRT and WM capacity, as measured using auditory digit span test (DST) and reading span test in older HA users ( Wang & Wong, 2023 ).…”

“…Rather, it suggests that the majority of individuals possess sufficient WM resources to meet the cognitive demands at this level. Thus, reduced memory performance may not significantly impact SRT in these conditions ( Wang & Wong, 2023 ). Conversely, in greater WM resource demand conditions, exemplified by five-digit or longer sequences, individuals with some level of memory performance decline may find their available WM resources inadequate to meet the demands required for digit recognition and recall.…”

“…Alternatively, the recognition difficulty of the five-digit sequence conditions might not have been sufficiently challenging, and the amount of WM resources required for the five-digit sequence condition could have been well within the capabilities of most participants. Therefore, in this study, we aim to build upon the foundation laid by Wang and Wong (2023) by recruiting a larger number of older HA users with potential cognitive decline to explore the aforementioned hypotheses.…”