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Spatial release from masking in a bottlenose dolphin Tursiops truncatus
Vladimir V Popov1, Alexander Ya Supin1, Alisa P Gvozdeva2
1Institute of Ecology and Evolution of the Russian Academy of Sciences, 33 Leninsky Prospect, Moscow 119071, Russia.
The Journal of the Acoustical Society of America
|April 3, 2020
Summary
Masking noise affects bottlenose dolphin hearing sensitivity, primarily shifting auditory thresholds rather than distorting the receiving beam. Hearing sensitivity decreased when noise came from the front, with greater impact on the same side as the noise source.
Area of Science:
- Marine biology
- Bioacoustics
- Auditory neuroscience
Background:
- Bottlenose dolphins (Tursiops truncatus) rely heavily on sound for navigation and communication.
- Understanding auditory masking is crucial for assessing anthropogenic noise impacts on marine mammals.
Purpose of the Study:
- To investigate the impact of masker sound on the auditory receiving beam of bottlenose dolphins.
- To evaluate how masker location influences auditory evoked potential (AEP) thresholds.
Main Methods:
- Auditory evoked potential (AEP) method was used to measure hearing thresholds.
- A 64 kHz tone pip signal was used to elicit rate following responses (RFR).
- Band-limited noise (45-90 kHz) at 105 dB re 1 μPa was used as a masker at various azimuths.
Main Results:
- Masked thresholds were elevated compared to baseline, indicating reduced sensitivity.
- The largest threshold increase occurred when the masker was directly ahead (0° azimuth).
- Masking caused an asymmetry in hearing, with higher thresholds for signals ipsilateral to the masker.
Conclusions:
- Masking primarily shifts auditory thresholds, with minimal deformation of the dolphin's receiving beam.
- The observed masking asymmetry suggests complex interactions within the dolphin's auditory system.
- Findings highlight the potential for noise pollution to impair dolphin acoustic perception.
