Recreational scuba divers' aversion to low-frequency underwater sound.

Area of Science:

• Marine acoustics
• Underwater acoustics
• Human physiology

Background:

• Increasing naval sonar use poses risks to recreational divers from low-frequency underwater sound (LFS).
• Understanding diver responses to LFS is crucial for assessing potential impacts on underwater activities.

Purpose of the Study:

• To characterize recreational scuba divers' subjective responses to LFS.
• To determine the impact of LFS on diver enjoyment, comfort, and underwater time.

Main Methods:

• Twenty-six recreational divers were exposed to various LFS signals (pure tone, sweeps) at different frequencies (100-500 Hz) and sound pressure levels (130-157 dB re 1 microPa) in a controlled tank environment.
• Divers rated their aversion to LFS and reported any perceived vibration using an underwater console.

Main Results:

• Diver aversion and vibration incidence increased with sound pressure level (SPL).
• Vibration incidence decreased with increasing frequency, while 100 Hz LFS elicited the most aversion.
• A U-shaped aversion function was observed, with minimum aversion at 250 Hz.

Conclusions:

• Diver aversion to LFS is dependent on SPL and frequency, with 100 Hz being the most aversive.
• LFS exposures up to 145 dB re 1 microPa within the 100-500 Hz range are predicted to have minimal impact on recreational divers.