Several mass strandings of beaked whales have recently been correlated with military exercises involving mid-frequency sonar
highlighting unknowns regarding hearing sensitivity in these species. We report the hearing abilities of a stranded juvenile
beaked whale (
Mesoplodon europaeus) measured with auditory evoked potentials. The beaked whale’s modulation rate transfer function (MRTF) measured with a 40-kHz
carrier showed responses up to an 1,800 Hz amplitude modulation (AM) rate. The MRTF was strongest at the 1,000 and 1,200 Hz
AM rates. The envelope following response (EFR) input–output functions were non-linear. The beaked whale was most sensitive
to high frequency signals between 40 and 80 kHz, but produced smaller evoked potentials to 5 kHz, the lowest frequency tested.
The beaked whale hearing range and sensitivity are similar to other odontocetes that have been measured.
Keywords Beaked whale -
Mesoplodon europaeus
- Hearing - Auditory evoked potential - Envelope following response - Modulation rate transfer function