Summary
Sound is a longitudinal wave that travels through many media
The speed of sound in air is: 343 m/s (at room temperature)
speed of sound depends on the media it travels:
material, pressure, temperature, aggregation state ……
ears detect sound waves and send electric signals to the brain
the audible range for human: 20-20,000 Hz
sound sources are special due to their “coloring” (content of harmonics)
musical instruments involve the production of standing waves
- three main types of instruments: string, wind and percussion instruments
- for string and wing instruments the frequency of the harmonics is an integer multiple of the fundamental one
- different notes are generated by changing the standing wave condition
Two steady sounds with nearly equal frequencies superimpose to form beats: periodic variation of the loudness of sound
The frequency of the sound from a moving object is shifted in frequency according to the Doppler effect.
- The shift in the frequency is constant as long as the velocity is.
- Doppler effect occurs for all kinds of waves.
When a source of waves moves faster than the speed of the waves--> shock wave is formed (edge of the shock-wave cone high amplitude)