Hearing Thresholds from Toadfish, Opsanus tau, Measured in the Laboratory and Field

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.