The mechanism for directional hearing in fish

Area of Science:

• Acoustics
• Bioacoustics
• Sensory Neuroscience

Background:

• Directional hearing is vital for vertebrate survival, enabling prey and predator detection.
• Underwater sound localization is challenging for fish due to minimal interaural cues, making the underlying mechanisms poorly understood.
• Previous hypotheses suggested extreme sensitivity to interaural differences or comparing sound pressure with particle motion.

Purpose of the Study:

• To empirically investigate the mechanisms of directional hearing in fish.
• To test proposed hypotheses regarding sound localization in the aquatic environment.
• To elucidate the sensory algorithm enabling directional acoustic startles in Danionella cerebrum.

Main Methods:

• Utilizing the transparent teleost Danionella cerebrum for empirical testing.
• Selectively controlling sound pressure and particle motion to dissect sensory input.
• Employing micro-computed tomography and optical vibrometry to analyze sensory structures.

Main Results:

• Both sound pressure and particle motion cues are essential for directional acoustic startles in fish.
• The relative phase between pressure and particle motion dictates the direction of sound localization.
• Danionella cerebrum possesses the necessary sensory structures to implement this sound localization mechanism.

Conclusions:

• Directional hearing in fish relies on a sophisticated integration of sound pressure and particle motion cues.
• The findings in Danionella cerebrum suggest a widespread mechanism for sound direction inference across vertebrate species.
• This research provides a definitive explanation for a long-standing mystery in fish bioacoustics.