As you may probably tell, I am still new to physics and in school, we're learning about waves right now. When I watched how strings vibrate, they looked like transverse wave.

So, my initial thought was all waves looked like transverse wave. But then, after learning the chapter about waves, I found out that sound is actually longitudinal wave. Or is it all the time?

How come strings vibrate like transverse wave but still produce sound?

  • 2
    $\begingroup$ A transversely vibrating drumhead can push the air unleashing longitudinal compression waves in it. $\endgroup$ Jan 13, 2018 at 14:54

1 Answer 1


In string instruments, the bridge will transfer the transverse motion of the string to a soundboard. This then moves to put the air above and below it in motion, causing a longitudinal wave.

The soundboard is also often part of a resonance cavity. For example, the body of an acoustic guitar is a Helmholtz resonator, where much of the sound comes from air moving in and out through the hole.

  • $\begingroup$ So does that mean when the energy is transferred through the solid, it is in transverse motion, but when the energy goes to gas, it changes to longitudinal wave? $\endgroup$ Jan 14, 2018 at 3:39
  • $\begingroup$ @AmmarSarif Terms like "transverse" and "longitudinal" are relative to the direction of propagation of the wave. But there is not really a wave in the soundboard or in the Helmholtz resonator. Or in a loudspeaker.. $\endgroup$
    – user137289
    Jan 14, 2018 at 10:39

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