Data from: Low-frequency temporary threshold shift not observed in spotted or ringed seals exposed to single air gun impulses

Underwater hearing thresholds were measured at 100 Hz in trained spotted
(Phoca largha) and ringed seals (Pusa hispida) before and immediately
following voluntary exposure to impulsive noise from a seismic air gun.
Auditory responses were determined from psychoacoustic data and behavioral
responses were scored from video recordings. Four successive exposure
conditions of increasing level were tested, with received unweighted sound
exposure levels from 165 to 181 dB re 1 μPa2 s and peak-to-peak sound
pressures from 190 to 207 dB re 1 μPa. There was no evidence that these
single seismic exposures altered hearing—including in the highest exposure
condition, which matched previous predictions of temporary threshold shift
(TTS) onset. Following training at low exposure levels, relatively mild
behavioral responses were observed for higher exposure levels. This
demonstrates that individuals can learn to tolerate loud, impulsive
sounds, but does not necessarily imply that similar sounds would not
elicit stronger behavioral responses in wild seals. The absence of
observed TTS confirms that regulatory guidelines (based on M-weighting)
for single impulse noise exposures are conservative for seals. However,
additional studies using multiple impulses and/or higher exposure levels
are needed to quantify exposure conditions that do produce measurable
changes in hearing sensitivity.