Sensitivity to airborne sounds in ice-dependent bearded seals

Area of Science:

• Marine biology
• Bioacoustics
• Arctic ecology

Background:

• The Arctic is warming, increasing human activity and noise pollution.
• Ice-associated marine mammals, like seals, rely heavily on sound for survival.
• Understanding seal hearing is crucial for assessing noise impacts in the Arctic.

Purpose of the Study:

• To measure the in-air hearing sensitivity of a bearded seal (Erignathus barbatus).
• To assess how ambient noise affects hearing thresholds across a wide frequency range.
• To estimate critical ratios for bearded seals to improve noise impact models.

Main Methods:

• Psychophysical methods were used to determine 50% detection thresholds.
• Measurements were taken outdoors in ambient conditions across 10 frequencies (0.04–51.2 kHz).
• Hearing thresholds were compared against background noise levels.

Main Results:

• Low to mid-frequency hearing (0.04–12.8 kHz) was masked by ambient noise.
• High-frequency hearing (25.6–51.2 kHz) provided absolute sensitivity measures.
• Bearded seal high-frequency hearing aligns with related species despite evolutionary divergence.

Conclusions:

• Bearded seal airborne hearing shows similarities with other northern phocid seals.
• Findings aid in predicting noise effects on seals in changing Arctic environments.
• Estimated critical ratios can enhance acoustic masking models for marine mammals.