Normal İşiten Bireylerde Gürlük Adaptasyonu

Abstract

Noise exposure can result in decreased I-wave amplitude values of auditory brainstem responses of individuals with over-threshold levels due to this spontaneous hearing nerve fibers, afferent fibers and this cognitive damage resulting in impairments in temporal coding skills.In this study on the identification of individuals with suspected hearing loss as a consequence of noise exposure, the effect of noise exposure that cause the loss of hearing nerve fibers with low spontaneous hearing nerve fibers as well as internal hair cell synapse, which are important for noise above supine noise in noise, are investigated. 69 subjects aged between 19 and 32 years with normal hearing thresholds participated in the study. The study was divided into 2 groups according to their noise survey scores. 1st group consists of individuals with noise exposure, 2nd group consists of individuals without noise exposure. In all, the click auditory brainstem responses ranged from 9.1 rate to 70-99 dB nHL intensity level. In the study group, the first wave amplitude of the auditory brainstem response decreased with increasing intensity, and in the control group, the first wave amplitude increased with intensity. In our study, the V/I amplitude ratio obtained in the study group at the 99 dB nHL intensity level was found to be approximately 60% higher than the control group. In the study, 6 experiments were performed depending on the modulated stimuli given to the individuals and the changes in the stimuli applied. In the study to evaluate the adaptation of the loudness in hidden hearing loss individuals, the loudness adaptation values ​​were found to be lower than the loudness adaptation values ​​obtained from the background noises by 180 seconds after the background noise was given for the study group. Despite the individual differences when compared to the unmodified and modulated stimuli in the study group, the loudness adaptation value in experiment 1 was found to be lower than the experiment 2 in the unmodulated stimulus after 180 seconds from stimulus stimulation. At the same time, in experiment 1 and experiment 2, as the modulation frequency increased, the value of adaptation of the gain also increased. For the experiment group 3, it was found that the loudness adaptation values ​​obtained from stimuli with different carrier frequencies were not affected after 180 seconds from the stimulus according to the initial gain adaptation value, but the maximum loudness adaptation value was found to be in1 kHz carrier frequency in Experiment 4. In Experiment 5, as the depth of modulation for group 1 increased, the adaptation of the gain was found to be increased. In Experiment 6, the maximum gain loudness adaptation change for the study group was obtained with a 50% modulation depth. In this study, it was found that all of the stimuli given under contralateral noise showed more adaptation especially to individuals with suspected hearing loss. In all of the experiments, it was thought that loudness adaptation values obtained for group 2 were found zero was either for loudness adaptation’s underdevelopment or its insufficient development. According to the results obtained in the study, the short-term adaptation values ​​obtained in individuals with hidden hearing loss-related noise exposure were found to be adaptive to changes in the auditory neuropathic and ribbon synaptic impairments. Low spontaneous rated hearing nerve fiber and temporal coding impairment are thought to be associated with adaptive size and abnormal loudness adaptation, especially under background noises. Key words: Loudness adaptation, GMFE, Hidden hearing loss, Matrix, İBC