sound
da shawn tan

1. pitch
1.1. depends on
1.1.1. frequency
2. vibrations
2.1. propagated by
2.1.1. longitudinal waves
2.1.1.1. through
2.1.1.1.1. compression and rarefraction
2.1.1.2. requires
2.1.1.2.1. A medium
3. loudness
3.1. depends on
3.1.1. amptitude
4. consists of
4.1. ultrasound
4.1.1. produce by
4.1.1.1. vibrations
4.2. audible frequencies
4.2.1. 20Hz-20kHz
4.2.2. produce by
4.2.2.1. vibrations
5. speed
5.1. in
5.1.1. solid>liquid>gas