Behavioral Hearing Thresholds and Distortion Product Otoacoustic Emissions in Cannabis Smokers

Purpose Cannabis is a widely used drug both medically and recreationally. The aim of this study was to determine if cannabis smoking is associated with changes in auditory function, as measured by behavioral hearing thresholds and/or distortion product otoacoustic emissions (DPOAEs). Method We investigated hearing thresholds and 2f₁-f₂ DPOAEs in 20 cannabis smokers and 20 nonsmokers between 18 and 28 years old. Behavioral thresholds were obtained from 0.25 to 16 kHz. DPOAEs were measured using discrete tones between f₂ of 0.5 and 19.03 kHz using an f₂/f₁ ratio of 1.22 and L₁/L₂ = 65/55 dB SPL. Thresholds and DPOAE amplitudes were compared between groups using linear mixed-effects models with sex and frequency as predictors. Results Behavioral thresholds in smokers did not differ significantly between smokers and nonsmokers (all ps > .05). Although not significant, long-term smokers exhibited poorer thresholds than short-term smokers and nonsmokers. Smokers generally exhibited lower DPOAE amplitudes than nonsmokers, although the differences were not significant. Male smokers had significantly poorer DPOAE amplitudes than male nonsmokers in the low frequencies (f₂ ≤ 2 kHz; p = .0245). Conclusion Results indicate that smoking cannabis may negatively alter the function of outer hair cells in young men. This subtle cochleopathology is evident in the absence of measurable differences in behavioral hearing thresholds between cannabis smokers and nonsmokers.