SOUND - The Squeeze that Travels

SOUND: the squeeze that travels When you speak, your voice reaches the next room, yet no air from your mouth makes the trip. What travels is a squeeze, passed from molecule to molecule. This video follows that squeeze: how it moves, why Newton's formula for its speed came out about 15 percent too low, how Laplace found the missing heat, and how the same simple wave explains pitch, loudness, interference, beats, harmonics, timbre, Chladni figures, the Doppler effect, sonic booms and diffraction. The wave pictures come from numerical solutions of the acoustic wave equation, and the sound demonstrations are synthesized from the same physics (headphones recommended). Chapters 0:00 Your voice, the next room, and a strange fact 0:53 Inside the air 1:21 A squeeze that travels (longitudinal waves) 2:14 1660: silence in a jar 2:58 How fast is sound? 3:40 1687: Newton's recipe 4:41 The missing fifteen percent 5:10 1816: the missing heat 6:14 One recipe, every material 6:48 Why a squeeze has to travel (the wave equation) 7:38 Pitch and wavelength 8:21 Loudness and decibels 8:51 When waves meet: interference 9:25 Silence from sound: noise cancelling 9:48 Beats 10:21 Trapped waves: standing waves and harmonics 11:05 Timbre 11:39 1787: drawing with sound (Chladni figures) 12:25 Moving sources: the Doppler effect 13:07 The sound barrier 13:31 Around the corner: diffraction 14:12 Shaping sound today 14:47 What sound is