A Real Tuning Fork

If you have ever played with a tuning fork, you know that they are interesting and fun, but they can also be expensive. For this experiment, we will use a regular fork from your kitchen to produce a beautiful tone.

To try this you will need:

  • a metal fork

Hold the handle of the fork in your hand and gently tap the tines (the pointy ends) with your fingernail. Listen to the sound. Not very impressive. In fact, you will have to listen very closely to hear it at all.

When you tap the tines of the fork, they vibrate. This causes the air around them to vibrate and the air carries the vibrations to your eardrum. Because the tines of your fork do not vibrate very strongly, you don't hear much sound.

If we want to hear the sound better, we need to get more of the vibrations to your ear. To do that, we will bypass the air and your eardrum. Instead, we will let the vibrations go directly to your inner ear, by using your teeth.

Yes, I said teeth. Your teeth are connected to your jaw bone. If we can make your teeth vibrate, the sound can travel directly to the inner ear, making the sound much louder and clearer. To do that, GENTLY place the handle of the fork into your mouth and hold it between your back teeth. GENTLY tap the tines of the fork with your finger and you will hear a loud, clear tone. You are now hearing through your teeth.

Through your teeth? Yes, the tines on the fork vibrate, causing the handle to vibrate too. That vibration causes your teeth to vibrate. They conduct the vibration to the bones of your skull, and to your inner ear. Because solids such as metal and bone are good at conducting vibration, you hear the sound very clearly.

Food manufacturers know about this and work very hard to be sure that cookies, crackers, etc., have a satisfying crunch. Luckily, that crunch sounds much louder to you than to someone nearby.

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