Ünlü-Ünlü Ses Geçişleri İle Oluşan Kortikal N1 Cevabını Oluşturan Akustik Olayların İncelenmesi

Abstract

It has been proven by studies that the sound transitions in vowel-vowel syllables with a change in F2 formant frequency evoke a response called acoustic change complex (ACC). Considering the ACC response evoked by the /ui/ stimulus, the contribution of the onset of /i/, which provides the acoustic change in the stimulus, and/or the contribution of the f2 frequency ramp occurring during the transition from /u/ to /i/ to the total response has not been examined previously. In this study, a total of 4 stimuli, including the "standard /ui/" stimulus, and the /u ramp/ stimulus where the /i/ sound is completely removed, and the /ui/ stimulus formed by 0.05 and 0.1 msec parts of the /i/ sound were utilized. The stimuli was presented at an intensity of 70 dB SPL to 20 participants. The results showed that the ACC N1 amplitudes evoked by the /ui/ stimulus (Md=-1.647) were significantly lower (p=0.029) than the amplitudes evoked by the /u ramp/ stimulus (Md=-2.957). As the /i/ sound was included in the stimulus, the ACC N1 amplitudes gradually decreased, although not reaching significance. When compared in terms of ADK N1 latency, the /u ramp/ stimulus had the shortest median latency (Md=652). The fact that the /u ramp/ stimulus has the largest amplitude and the shortest latency value shows that the f2 formant frequency ramp has a substantial contribution to the total change response. In future studies, using ramp stimuli with different f2 formant frequency changes, and examining the contribution of the f2 ramp to the auditory discrimination process may be suggested. Besides, the extent to which the ramp response affects the total acoustic change response in individuals using cochlear implants and hearing aids can be studied.