The ocean is a world of sound, and whales are some of its loudest inhabitants, producing vocalizations that can travel across entire ocean basins. These sounds include the low, rumbling songs of baleen whales and the sharp, powerful clicks of deep-diving toothed whales, measured at extraordinary volumes. This spectacular loudness raises a serious question for anyone submerged nearby: can the sound of a whale be loud enough to cause deafness?
The Science of Whale Sound Production
Whales produce intense sounds for two primary purposes: long-distance communication and precise echolocation. The sound-making mechanism differs significantly between the two major whale groups. Baleen whales, such as the Blue Whale, create long, low-frequency songs using a specialized larynx that recycles air internally, allowing them to vocalize without exhaling air. These powerful, continuous low-frequency calls can reach source levels of up to 177 decibels (dB) re 1 \(\mu\)Pa at 1 m.
Toothed whales, like the Sperm Whale, are the record-holders for the loudest animal sound on Earth, generating short, sharp clicks for hunting and navigation. These clicks are produced in the nasal passages using structures called phonic lips, and the sound is focused by the spermaceti organ in the whale’s head. The resulting acoustic beam is highly directional and intense, with peak source levels estimated to reach as high as 236 dB re 1 \(\mu\)Pa at 1 m. This extreme volume is necessary for their echolocation to function effectively while hunting.
Underwater Acoustics and Human Hearing
The decibel levels recorded for whales are measured in water, a different acoustic medium than air. Sound travels more than four times faster in water, and the density difference creates an acoustic impedance mismatch for the human ear. Our hearing apparatus, including the eardrum and middle ear bones, is designed to efficiently transfer subtle air pressure changes into the fluid of the inner ear.
When a human is submerged, this air-transfer system becomes ineffective. The sound bypasses the normal pathway, and pressure waves are transmitted directly through the skull bones to the inner ear, a process known as bone conduction. Because the sound energy is not amplified by the middle ear, the human ear is significantly less sensitive to sound underwater. Maximum sensitivity for underwater hearing in humans occurs around 500 Hertz (Hz), a lower frequency than our best hearing range in air.
Assessing the Risk of Permanent Hearing Loss
The risk of permanent deafness from a whale vocalization is exceptionally low for the average person. The key factor is the threshold for auditory injury, known as Permanent Threshold Shift (PTS), the level at which the inner ear sustains irreversible damage. Studies on human divers indicate that Temporary Threshold Shift (TTS)—a reversible form of hearing impairment—occurs at exposure levels around 180 to 190 dB re 1 \(\mu\)Pa for short durations.
The most powerful whale sound, the Sperm Whale’s 236 dB click, is a short, pulsed signal whose intensity drops off rapidly with distance due to spherical spreading. A diver would need to be within meters of the whale to approach the auditory injury threshold. The greatest danger from intense underwater sound is not always hearing loss, but the non-auditory effects caused by pressure waves affecting air-filled cavities. Divers exposed to levels around 176–185 dB have reported dizziness, pressure, and the sensation of water spraying in their mask, indicating a physical response.
Real-World Exposure and Safety Measures
The average person is unlikely to encounter a whale at the dangerously close range required to cause harm. Whale-watching activities and recreational diving maintain a safe distance, and sound intensity quickly dissipates. The threat is mainly hypothetical for the general public, but it is a concern for specialized professionals like military sonar operators and marine researchers.
These professionals use specialized gear, such as wet-suit hoods, which provide sound attenuation. Regulations for military divers establish exposure limits to prevent acoustic trauma, with thresholds for hooded divers often set around 180 dB re 1 \(\mu\)Pa. Human-made noise, such as high-powered military sonar systems, can also generate source levels of up to 230 dB re 1 \(\mu\)Pa, posing a comparable risk to both humans and marine life.