Why do not you hear beats when different keys on the piano are played at same time?

You do hear beats when different keys on the piano are played at the same time. The phenomenon of beats is the result of the interference of two sound waves with slightly different frequencies. When the two waves are in phase, they reinforce each other, resulting in a louder sound. When the two waves are out of phase, they cancel each other out, resulting in a softer sound. The rate at which the waves go in and out of phase is called the beat frequency.

The beat frequency is equal to the difference between the frequencies of the two waves. For example, if two notes are played on the piano that are one semitone apart, the beat frequency will be 1 Hz. This means that the sound will alternate between being louder and softer once per second.

The greater the difference between the frequencies of the two notes, the faster the beat frequency will be. This is why beats are more noticeable when two notes are played that are far apart on the piano.

Beats can also be heard when two notes are played on different instruments that are not tuned to the same pitch. For example, if you play a note on a piano and then play the same note on a guitar, you may hear beats if the guitar is not tuned properly.

Beats can be a useful tool for tuning instruments. By listening for the beat frequency, you can adjust the tuning of an instrument until the beats disappear.