[Association between age-related hearing loss and cognitive function, and analysis of the threshold effect on speech perception in noisy environments]

Objective:To investigate the relationships between age-related hearing loss, cognitive function, and speech perception ability under noisy conditions, and to analyze whether a threshold effect exists between hearing level and speech perception ability in noise, so as to provide guidance for early diagnosis and intervention in patients with hearing loss. Methods:A total of 129 elderly subjects with bilaterally symmetric hearing and varying hearing levels were recruited. Hearing level was reflected by the pure-tone average（PTA） of both ears, and cognitive function was evaluated using the Montreal Cognitive Assessment（MoCA）. Speech perception performance was measured under three listening environments: quiet, signal-to-noise ratio（SNR） of +5 dB and 0 dB. The psychometric function slope of speech perception in noise was calculated to quantify the relative decline degree of an individual's speech perception ability with the deterioration of listening environment, namely the anti-noise ability. The correlations between PTA, MoCA scores and Slope were analyzed, and the piecewise linear regression method was used to calculate the PTA inflection point affecting the subjects' anti-noise ability. Results:After controlling for covariates including age, gender and years of education, PTA was significantly negatively correlated with MoCA scores（r=-0.236, Bootstrap 95%CI[-0.395, -0.058], FDR corrected P=0.012）. After further controlling for MoCA scores in addition to the above covariates, PTA remained significantly negatively correlated with Slope（r=-0.291, Bootstrap 95%CI[-0.451, -0.114], FDR corrected P=0.003）. However, no significant correlation was found between MoCA and Slope after controlling for age, gender, years of education and PTA（P>0.05）. Furthermore, piecewise linear regression showed a better fit for the relationship between PTA and Slope compared with linear regression（linear regression R²=0.147, piecewise linear regression R²=0.194, F[2, 125]=3.639, P=0.029）. The piecewise linear regression model revealed a threshold effect between PTA and Slope located at 25-26 dB HL, 95%CI 20-45 dB HL. Conclusion:Age-related hearing loss is associated with poorer cognitive performance and reduced resistance to noise interference. The relationship between hearing loss and anti-noise interference ability is not linear but exhibits a threshold effect. When PTA exceeds 25-26 dB HL, subjects' speech perception ability becomes more vulnerable to noise interference, and their anti-noise capacity declines at an accelerated rate with further hearing deterioration. This study indicates that the anti-noise interference ability of speech perception decreases when the hearing threshold exceeds 25-26 dB HL, providing an objective basis for early diagnosis and intervention of speech function in patients with hearing loss.