sound lesson 1 knight, d. c. (1960). the first book of sound: a basic guide to the science of...
TRANSCRIPT
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