Introduction of Sound Santiago Suarez

1. Introduction of SoundSantiago Suarez

2. Sound Sound is a vibration that propagates as a mechanical wave of pressure and displacement. • As a mechanical wave, sound requires a medium. • Sound cannot propagate through a vacuum. • There is no sound in outer space. • As a longitudinal wave, sound is a rapid variation in pressure that propagates. • Regions of above normal pressure (regions under compression) are called compressions or condensations. • Regions of below normal pressure (regions under tension) are calledrarefactions or dilations.

3. Compression & Rarefaction

4. Amplitude The amplitude of a sound wave corresponds to its intensity or loudness. The intensity of a sound is … • a measure of its power density • usually measured on a logarithmic scale. The loudness of a sound is its intensity as perceived by the human ear.

5. Frequency The frequency of a wave refers to how often the particles of the medium vibrate when a wave passes through the medium. The frequency of a sound wave corresponds to its pitch. Pitch: The quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone. • The upper frequency limit for human hearing is around 18,000 to 20,000 Hz. • Frequencies above the range of human hearing are ultrasonic. • The lower frequency limit for human hearing is around 18 to 20 Hz. • Frequencies below the range of human hearing are infrasonic. The frequency of a sound wave does not change as the sound wave propagates.

6. The Doppler Effect • The Doppler effect, named after the Austrian physicist Christian Doppler, who proposed it in 1842 in Prague, is the change in frequency of a wave (or other periodic event) for an observer moving relative to its source. The pitch rises when the source gets closer and it falls and when it goes away

7. Videos https://www.youtube.com/watch?v=94pZJT4qips (Compression and Rarefaction https://www.youtube.com/watch?v=94pZJT4qips (Doppler Effect)

8. Thank you for your time