Dolphin echo-delay resolution measured with a jittered-echo paradigm

Area of Science:

• Marine biology
• Bioacoustics
• Sensory neuroscience

Background:

• Bottlenose dolphins (Tursiops truncatus) rely on biosonar for navigation and foraging.
• Understanding the fine-grained resolution of their echo delay perception is crucial for deciphering echolocation mechanisms.

Purpose of the Study:

• To investigate the echo delay resolution of bottlenose dolphin biosonar.
• To determine the minimum detectable delay difference in dolphin echolocation.
• To explore the role of echo phase information in dolphin biosonar range estimation.

Main Methods:

• Utilized a "jittered" echo paradigm with electronic echoes to test delay discrimination.
• Dolphins performed an echo-change detection task with varying jitter delay values (0-20 μs).
• A passive listening task assessed detection of timing and polarity changes in simulated echoes.

Main Results:

• Dolphins achieved a mean jitter delay threshold of 1.3 μs.
• Error functions indicated sensitivity to echo phase, similar to bats.
• Dolphins could discriminate echoes jittered in polarity but not passively detect timing/polarity changes.

Conclusions:

• The dolphin biosonar range estimator is sensitive to echo phase information.
• Dolphins exhibit high precision in detecting temporal changes in biosonar echoes.
• Passive listening capabilities for timing and polarity changes are limited compared to active biosonar discrimination.