Listening Underwater: A Small Experiment in Swimming Design

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Question

I often listen to music while walking, eating, and exercising. A waterproof pair of bone-conduction headphones suggested a simple question: can I also listen to music continuously while swimming?

The interesting part was not whether the headphones survived water. It was whether the whole system—signal, sound propagation, breathing, body motion, and safety—could work together.

First attempt: Bluetooth

The initial plan was to keep a phone nearby in a waterproof pouch and connect the headphones through Bluetooth. The plan failed for a basic physical reason: the connection dropped as soon as either the phone or the headphones went underwater.

During normal swimming it is difficult to keep both devices above the surface. The Bluetooth design was therefore rejected, not because of the interface or the battery, but because the transmission medium imposed a hard constraint.

Second attempt: offline storage

The headphones could play locally stored audio, so I converted several songs to a supported format and removed the phone from the system. This solved the connectivity problem—but exposed a new one.

Air and water transmit sound differently. With bone-conduction headphones, the perceived sound underwater came from both the headset and the surrounding water. As I moved between the surface and underwater, volume and timbre changed abruptly. The best posture therefore had to minimize transitions, splashes, and asymmetric movement around the ears.

Three baselines

Breaststroke

Breaststroke repeatedly moves the head through the surface for breathing. The perceived volume rises and falls with each cycle. It can be acceptable for music with a relatively even sound profile, but it is poor for a continuous listening experience.

Freestyle

Rotating the head makes the left and right sides experience different acoustic conditions. Hand entry and splashes add noise. Across these factors, the listening experience was unstable.

Backstroke

Backstroke keeps the head in a more stable relationship with the water, but the recovering arms can strike the headset or generate splash noise. Long sessions also create neck fatigue, and looking upward makes collision awareness harder.

A fourth posture

The most promising design was a modified backstroke: keep the body on the surface, the ears and headphones consistently underwater, and the face above water for breathing. One hand supports the neck, the other helps stabilize the body, and the legs provide propulsion with a breaststroke-like kick.

This posture directly targets the mechanisms identified above:

• no Bluetooth link is needed;
• the headphones remain in one acoustic medium;
• breathing does not repeatedly move the ears across the surface;
• the arms do not sweep past the headset;
• fewer splashes reduce competing noise.

Subjectively, it produced the most continuous sound among the tested postures.

Evidence and limitations

The experiment had a sample size of one: one swimmer, one headset, one session, and a subjective outcome. The experiment took place in the deep-water area of a single pool. I did not define a quantitative listening score, and mood, technique, music choice, and pool conditions may all have affected the result.

In other words, the experiment found a useful design hypothesis—not a general law.

Open questions

• How should listening continuity be measured: perceived loudness variance, intelligibility, or subjective comfort?
• How much of the underwater effect comes from water conduction versus bone conduction?
• Would the same ranking hold for other swimmers, music genres, headsets, and pools?
• Can a posture improve listening without compromising ordinary swimming safety and efficiency?

The small lesson is broader than swimming: once a goal meets a physical constraint, progress often comes from redesigning the surrounding system rather than forcing the original solution to work.