Hearing Thresholds from Toadfish, <i>Opsanus tau</i>, Measured in the Laboratory and Field

Abstract

Laboratory and field experiments are described in which toadfish hearing was investigated. The threshold to tonal stimuli determined in the laboratory using a conditional heart rate technique agreed closely with the field-determined threshold using an unconditional behavioral response. Below 150 Hz, the hearing threshold was about 100 dB re 1 μN/m2. Above 200 Hz, it increased rapidly at about 22 dB/oct. In addition to the tonal threshold experiments, a threshold to prerecorded playbacks of toadfish sounds was measured in the field. This threshold was about 15 dB higher than the tonal threshold in the same frequency range.