Separate and combined effects of a benzodiazepine (alprazolam) and noise on auditory brainstem responses in man.

Auditory brainstem responses (ABRs) were recorded in 60 male or female, anxious or anxiety-free university students, before and after separated or simultaneous intake of alprazolam and exposure to noise. A significant increase of the latencies of the ABRs was found when subjects took alprazolam. This effect is consistent with the presence of gamma-aminobutyric acid (GABA), one of the neurotransmitters at terminals of cochlear efferent fibres A significant increase of the latencies was observed after noise alone. In subjects taking alprazolam when they are exposed to noise, the effect of noise on the ABR latencies is reduced, but not abolished. The effects of alprazolam on the ABR are consistent with the presence of GABA in the medulla and pons. Significant effects of noise upon III-V and I-V intervals suggest that auditory 'fatigue' may involve a retrocochlear component. Differences due to sex appear to be abolished by anxiety.

[Level of anxiety and effects of moderate noise on early auditory evoked potentials]. / Niveau d'anxiété et effets de bruits modérés sur les potentiels évoqués auditifs précoces.

Thirty men and 30 women, 20-25 years old, and selected for presence or absence of anxiety were exposed successively for 15 min to four different noises at the same continuous equivalent level LAeq = 75 dB. Auditory brainstem evoked potentials were recorded before and after exposure to each noise. No difference was found between these noises as to their effects upon evoked potentials. After exposure to noise a significant lengthening of L1, L3 and L5 latencies was observed in men; in women a significant lengthening of L3 and L5 latencies was also present. At the same time, I-V and III-V intervals were significantly increased, without any sex-linked difference, and without any change in I-III interval. L3 and L5 latencies are significantly longer in men than in women; lengthening by noise of L1 and L3 latencies was found significantly longer in men than in women; lengthening by noise of I-V interval was found significantly more important in anxious subjects, without any sex-linked difference. L3 lengthening was also found significantly longer in anxious men than in anxiety-free ones.

[Effects of moderate noises on early auditory evoked potentials in man, in relation to age]. / Effets de bruits modérés sur les potentiels évoqués auditifs précoces, chez l'homme, en fonction de l'âge.

Thirty men and thirty women, the first half of them 40-50 years old, and the other half 15-20 years old, were exposed successively for 15 min to four different noises at the same continuous equivalent level LAeq = 75 dB. Auditory brainstem evoked potentials were recorded before and after exposure to each noise. No difference was found between these noises as to their effects upon evoked potentials. After exposure to noise, a significant lengthening of L1, L3 and L5 latencies was observed in men. No significant lengthening was observed in women, although a lengthening of latencies was present in a majority of them. The three latencies, L3 and L5 latencies in particular, were found significantly longer in men than in women. L1 and L5 latencies were significantly more lengthened by noise in men than in women. In both sexes, L5 latencies were found significantly longer in older subjects; the same was true of L3 latencies in male subjects. Noise did not significantly modify intervals between peaks. I-V interval was found significantly longer in older male and female subjects; the same was true of I-III intervals in men.