MEASUREMENT OF AUDITORY THRESHOLD IN FISH ES BY PIEZOELECTRIC SENSOR

Using a classical respiratory conditioning technique, this experiment was carried out to examine the possibility of using a piezoelectric se nsor (Kynar; 20 mm long, 0.2 mm thick) to observe a conditioned respon se. mie used 2 fishes of different body style, the bastard halibut Par alichthys olivaceus and the tilapia Tilapia niloticus. The sensor was fitted on a gill cover to detect the respiratory activity, opening and shutting motion. The heart-beat was detected by EGG. After classical conditioning, the conditioning response was measured as suppression bo th in the respiratory activity and the heart-beat. The two factors coi ncided with each other. The method of measuring the respiratory activi ty by the piezoelectric sensor was found to be very useful for measuri ng the auditory threshold because of its ease of operation, apparent r esponse and greater signal than that of the ECG.