Romberg Tiburon Center for Environmental Studies

Image: Ripples on water

SF State's bayside marine and estuarine research facility.

Rosenberg Institute Discovery Day Open House at the Romberg Tiburon Center

2017 Discovery Day

Data Collection Results

  • Does sound travel faster in air or in water?

Creatures living in the marine environment face a different sensory environment from those living in air. There is less light, and it doesn’t travel very far, due to absorption by phytoplankton and various materials in the water. Sound, on the other hand, travels great distances underwater without being absorbed. For these reasons, hearing is the most important of the senses for many creatures living in the Bay. One of the simplest properties of sound is how fast it propagates. In this Citizen Science investigation, teams of Discovery Day visitors made a direct measurement of the speed of sound.


Using an oscilloscope, they estimated the time delay for sound (a rock thrown in the water!) to propagate between two hydrophones. They then divided the distance between hydrophones by the time to get the sound speed. Most visitors guessed that sound travelled slower underwater than in air. So some of them also measured the speed of sound in air, with a similar measurement. Then they entered their initials and their experimental results into a table, shown below:

















The emphasis of this exercise was on original measurements rather than comparison with “accepted values.”  However, these results are not far off!!!  And to the surprise of many, sound travels a lot faster underwater than in air.



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