posted on 2021-10-11, 17:56authored bySarah M. Theodoroff, Frederick J. Gallun, Garnett P. McMillan, Michelle Molis, Nirmal Srinivasan, Jane Gordon, Daniel McDermott, Dawn Konrad-Martin
Purpose: Type 2 diabetes mellitus (DM2) is associated with impaired hearing. However, the evidence is less clear if DM2 can lead to difficulty understanding speech in complex acoustic environments, independently of age and hearing loss effects. The purpose of this study was to estimate the magnitude of DM2-related effects on speech understanding in the presence of competing speech after adjusting for age and hearing.
Method: A cross-sectional study design was used to investigate the relationship between DM2 and speech understanding in 190 Veterans (Mage = 47 years, range: 25–76). Participants were classified as having no diabetes (n = 74), prediabetes (n = 19), or DM2 that was well controlled (n = 24) or poorly controlled (n = 73). A test of spatial release from masking (SRM) was presented in a virtual acoustical simulation over insert earphones with multiple talkers using sentences from the coordinate response measure corpus to determine the target-to-masker ratio (TMR) required for 50% correct identification of target speech. A linear mixed model of the TMR results was used to estimate SRM and separate effects of diabetes group, age, and low-frequency pure-tone average (PTA-low) and high-frequency pure-tone average. A separate model estimated the effects of DM2 on PTA-low.
Results: After adjusting for hearing and age, diabetes-related effects remained among those whose DM2 was well controlled, showing an SRM loss of approximately 0.5 dB. Results also showed effects of hearing loss and age, consistent with the literature on people without DM2. Low-frequency hearing loss was greater among those with DM2.
Conclusions: In a large cohort of Veterans, low-frequency hearing loss and older age negatively impact speech understanding. Compared with nondiabetics, individuals with controlled DM2 have additional auditory deficits beyond those associated with hearing loss or aging. These results provide a potential explanation for why individuals who have diabetes and/or are older often report difficulty understanding speech in real-world listening environments.
Supplemental Material S1. Statistical appendix.
Supplemental Materials S2-S9. Figures display the TMR and SRM results in the reverberant environmental setting, which complement the results in the anechoic environmental setting as provided in the manuscript.
Theodoroff, S. M., Gallun, F. J., McMillan, G. P., Molis, M., Srinivasan, N., Gordon, J., McDermott, D., & Konrad-Martin, D. (2021). Impacts of diabetes, aging, and hearing loss on speech-on-speech masking and spatial release in a large Veterean cohort. American Journal of Audiology. Advance online publication. https://doi.org/10.1044/2021_AJA-21-00022
This material is the result of work supported by VA Rehabilitation Research and Development Service Merit Review Award C7455R, awarded to Dawn Konrad-Martin, and with resources and the use of facilities at the National Center for Rehabilitative Auditory Research (under Research Center Award C2361C, awarded to M. Patrick Feeney) at the VA Portland Health Care System in Portland, Oregon.