Mapping Critical Age Ranges in Age-Related Hearing Decline Using LOESS Regression: An Early Warning Window for High-Frequency Changes Beginning at Age 40

Age-related hearing loss (ARHL) is the most prevalent sensory impairment worldwide, affecting more than one-third of adults aged 65 years or older. Early detection and intervention are essential for improving quality of life and reducing dementia-related risks. However, conventional one-size-fits-all screening strategies may fail to detect early frequency-specific declines.

The proposed cross-sectional study aimed to identify the critical age ranges during which hearing thresholds increased most markedly at different frequencies. Hearing thresholds at seven standard frequencies (0.125–8 kHz) were analyzed among outpatients with symmetric bilateral hearing to inform more targeted clinical screening.

We retrospectively analyzed pure-tone audiometry data from both ears of 11,507 patients who visited our otolaryngology clinic between 2021 and 2025. Pearson correlation and LOESS regression were used for statistical analysis.

Significant positive correlations between age and hearing thresholds were observed across all frequencies (p < 0.001). The critical age ranges associated with the greatest threshold differences were 43–52 years for high frequencies, 48–57 years for mid frequencies, and 63–72 years for low frequencies.

This large-scale study identified distinct frequency-specific critical age ranges for ARHL among Chinese outpatients. The findings identify ages 43–52 as a critical period for high-frequency hearing decline, providing a clear basis for targeted screening and timely clinical management.