Sound Lesson 1

Knight, D. C. (1960). The First Book of Sound: A Basic Guide to the Science of Acoustics (p. 80). New York: Franklin Watts, Inc.

BrainstormWhat items can you think of that

produce sounds?What common trait(s) can you

see between these items?

Sound from vibrating sourceshttp://www.youtube.com/watch?v

=70xFo0LFXa8

Longitudinal nature of sound

As sinusoidal waveform

Medium for transmission of soundhttp://www.youtube.com/watch?v

=_ckjttBin58

Differing speeds of sound

Alvin and the ChipmunksMusic group

created in 1958, consisting of three animated chipmunks singing in high-pitched voices

Won six Grammy awards

How were these songs created? (Hold that thought)

Chipmunks singing

Amplitude

Large amplitude Small amplitude

Amplitude is the magnitude of change in pressure during one oscillation, and is reflective of the amount of energy in a wave.

Frequency

Low frequency (440Hz) High frequency (880Hz)

Frequency is a measure of how fast the wave is vibrating. Frequency is measured in hertz (Hz). One hertz is one wave per second.

Loudness & Pitch

LoudnessDepends on amplitude of sound

wave - the larger the amplitude, the louder the sound.

PitchDepends on frequency of the

wave - the higher the frequency and the higher the pitch.

Ahmad’s inaudible MP3 fileAhmad has 2134 MP3 files, but

finds that one of them is very soft.

He has to turn up the volume of his iPod when listening, or he can’t hear the lyrics.

When the next track comes on after this song, the volume is too high.

How can this problem be remedied?

Problem track Typical song volume

Alvin and the ChipmunksHow were these

songs created?

Cathode-ray Oscilloscope (CRO)

Behind the CRO

(Optional) Doppler Effecthttp://www.surendranath.org/Appl

ets/Waves/Doppler/DopplerApplet.html

Next lesson…Audible range of soundDetermining speed of sound in

airProduction of an echoUltrasound and uses