Can you play the guitar underwater?

Episode Summary

Executive Summary: The episode investigates whether a guitar can be played underwater. Through lab tests and an underwater band’s experience, it shows that standard guitars sound muted and bass-light when submerged because water dampens vibration and air-to-water acoustic mismatch blocks sound. Yet with special instruments and hydrophone amplification, underwater music is possible.

Main Topics: Testing a Guitar Underwater (Priority: 5/5): CrowdScience answers a child’s question by submerging a guitar, first with water filling the body and then fully underwater, to observe how the sound changes. Acoustics of Guitars on Land vs. Water (Priority: 5/5): Experts explain how guitar sound depends on string vibration, the soundboard, and the guitar body acting as a Helmholtz resonator; water disrupts all of these mechanisms. Why Sound Transfers Poorly from Water to Air (Priority: 4/5): The episode explains that sound travels differently in water and air, and the acoustic impedance mismatch causes most underwater sound to reflect back rather than reach human ears. Hydrophones and Measurement in Underwater Acoustics (Priority: 4/5): A hydrophone inside the tank captures underwater guitar sounds far better than normal microphones outside, demonstrating how technology can overcome the air-water barrier. Aquasonic and Specialized Underwater Instruments (Priority: 5/5): The Danish ensemble Aquasonic shows that underwater performance can work if instruments are redesigned, including custom instruments like the roticorda and modified violins. The Importance of Tank Design and De-Aerated Water (Priority: 3/5): The group’s performances depend on factors such as tank depth, instrument position, and removing air bubbles from the water to improve resonance and clarity.

Key Arguments: A standard guitar is not designed for underwater use, so its strings and soundboard lose efficiency when submerged. Filling the guitar body with water reduces the Helmholtz resonance effect and removes bass response, making the sound muted. Fully submerging the guitar makes it much quieter because sound does not transmit efficiently from water to air for outside listeners. Human ears are adapted for air, so even when a guitar makes sound underwater, people above water hear very little of it. Using a hydrophone inside the water reveals that the instrument is still producing sound, just in a very different acoustic environment. Underwater music becomes viable when instruments are specially engineered for water, as shown by Aquasonic’s custom instruments and performance methods. Water conditions matter: bubbles, depth, and placement in the tank can significantly alter the quality of underwater sound.

Data Points: Sound speed in water: 1480 m/s - Freya Malcha explains that sound travels much faster in water than in air. Sound speed in air: 343 m/s - Used to contrast how differently sound propagates in air versus water. Relative speed of sound: 4.3 times faster in water - Derived comparison between water and air propagation speed. Water density vs air: 800 times denser - Used to explain the acoustic impedance mismatch at the water-air boundary. Tank placement sensitivity: 15 cm - Robert says a small positional change in the tank can noticeably affect how the instrument sounds. Aquasonic performance setup: 5 aquariums on stage - The underwater ensemble evolved into a concert format with multiple submerged performance stations. Number of musicians submerged: 5 - Aquasonic’s concert features five musicians fully submerged and performing underwater.

Pivotal Quotes: "I guess guitars aren't really designed to work underwater, is probably the main problem." — Dr. Freya Malcha: Initial expert reaction to the listener’s question at the National Physical Laboratory. "The short answer is no. The long answer is we I think maybe we tried it in the very, very beginning. Water creates so much resistance." — Robert Carlson: Aquasonic director’s first response when asked whether a guitar can be played underwater. "You can't play it in the way you would expect it to sound on land, but you are playing something, and it is a guitar and it is making a musical sound." — Robert Carlson: Conclusion after testing the guitar in Aquasonic’s specialized underwater setup.

Implications: Ordinary guitars are poor underwater instruments, but underwater music is feasible with custom design, hydrophone amplification, and adapted technique. The episode highlights how acoustics, biology, and engineering shape what counts as “music” underwater.