Noise interference with echo delay discrimination in bat biosonar.

Area of Science:

• Bioacoustics
• Animal Behavior
• Sensory Neuroscience

Background:

• Echolocating bats navigate and hunt using self-generated sound pulses and their returning echoes.
• Discrimination of echo delay is crucial for determining range and detecting objects.

Purpose of the Study:

• To investigate the impact of noise on the echo-delay discrimination abilities of big brown bats (Eptesicus fuscus).
• To determine the bats' compensatory strategies in response to increasing noise levels.

Main Methods:

• Bats were trained in a two-choice task to discriminate echo delay differences.
• Noise was introduced at increasing amplitudes to assess performance thresholds.
• Bat vocalization amplitude and duration were monitored during noise exposure.

Main Results:

• Bats could discriminate echo delays with thresholds comparable to previous studies.
• Bats increased broadcast amplitude and duration to compensate for noise, extending performance to higher noise levels.
• At low signal-to-noise ratios, performance was limited by side-peak ambiguity in delay accuracy.

Conclusions:

• Big brown bats exhibit robust echo-delay discrimination capabilities.
• Vocalization compensation is a key strategy enabling bats to maintain echolocation performance in noisy environments.
• Side-peak ambiguity significantly impacts echo-delay accuracy at low signal-to-noise ratios.