chapter 21 musical sounds. 1. noise versus music wham - noise and wave forms pitch pitch loudness...
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Chapter 21Chapter 21
Musical SoundsMusical Sounds
1. NOISE VERSUS MUSIC1. NOISE VERSUS MUSIC
Wham - Noise and Wave FormsWham - Noise and Wave Forms
PitchPitch
LoudnessLoudness
QualityQuality
Three characteristics of a musical tone:Three characteristics of a musical tone:
2. PITCH2. PITCH
The pitch of a sound relates to its frequency.
The exact relationship is complex.
For simple sounds, the greater the frequency the
greater the pitch.
For complex sounds, pitch assignment is an
involved psychological process.
Change pitch by altering the vibrating source.Change pitch by altering the vibrating source.
Response to high pitch usually declines
with age.
3. SOUND INTENSITY AND LOUDNESS3. SOUND INTENSITY AND LOUDNESS
Intensity - refers to pressure variations
The human ear can hear intensities over a tremendously large range.
Loudness depends on intensity in a complicated way. It does not increase as rapidly as intensity.
Intensity is directly proportional to the pressure amplitude squared.
2AI
LoudnessLoudness
= 10 log(I/Io)
Measured in decibels (db)A difference of 10 dB corresponds to a ratio of
intensities of 10X.
Loudness depends on our sensitivity to Loudness depends on our sensitivity to different frequencies.different frequencies.
Common Sound IntensitiesCommon Sound Intensities
Source of Sound Intensity (W/m2) Sound Level (db)
Jet 30 m away 102 140
Air-raid siren, nearby 1 120
Disco music, amplified 10-1 110
Riveter 10-3 90
Busy street traffic 10-5 70
Conversation in home 10-6 60
Quiet radio in home 10-8 40
Whisper 10-10 20
Rustle of leaves 10-11 10
Threshold of hearing 10-12 0
Response of the Ear atConstant Loudness
Response of the Ear atConstant Loudness
4. QUALITY4. QUALITY
Quality is the same thing as timbre.
It is easy to distinguish two different
instruments playing the same note.
The quality of a musical sound depends on
the number of partial tones and their
relative intensities.
Same Note - Different InstrumentSame Note - Different Instrument
Human VoiceHuman Voice
Harmonics and OvertonesHarmonics and Overtones
The lowest frequency associated with a musical note is called the fundamental frequency.
Any partial that is a whole number multiple of the fundamental frequency is called a harmonic.
Overtones are consecutively numbered partials of frequency higher than the fundamental.
Adding HarmonicsAdding Harmonics
1st
2nd
Sum
Demo - Harmonics on a GuitarDemo - Harmonics on a Guitar
Demo - Organ PipeDemo - Organ Pipe
Speaker ShortcomingsSpeaker Shortcomings
The brain can fill in missing lower
harmonics that small speakers cannot
create.
5. MUSICAL INSTRUMENTS5. MUSICAL INSTRUMENTS
Three basic types stringed, air column, and percussion
Because of energy loss, string sections in orchestras are generally larger.
Electronic
6. FOURIER ANALYSIS6. FOURIER ANALYSIS
The eardrum responds to a sum of all the waves arriving at a particular instant. Yet the individual sounds are “heard.”
Any waveform is composed of an infinite number of simple sine waves of various frequencies and amplitudes.
Adding HarmonicsAdding Harmonics
Spreadsheet
7. COMPACT DISCS7. COMPACT DISCS
Phonograph players give analog signals.Phonograph players give analog signals.
Digital signal is in binary code.Digital signal is in binary code.
CD has flats and pits and is sampled 44,100 times CD has flats and pits and is sampled 44,100 times
per second.per second.
Diatonic C Major ScaleDiatonic C Major Scale
Letter Frequency FrequencyLetter Frequency FrequencyNote Name (Hz) ratio Interval
do C 264 9/8 Wholere D 297 10/9 Wholemi E 330 16/15 Halffa F 352 9/8 Wholesol G 396 10/9 Wholela A 440 9/8 Wholeti B 495 16/15 Halfdo C 528
Chapter 21 Review QuestionsChapter 21 Review Questions
The quality of a musical note can be changed by simply playing the note on a different instrument.
The quality of a musical note can be changed by simply playing the note on a different instrument.
(a) True
(b) False
(a) True
If the note middle C has a pitch of 262 vibrations per second, its second overtone on a vibrating string has a frequency of
If the note middle C has a pitch of 262 vibrations per second, its second overtone on a vibrating string has a frequency of
(a) 131 vibrations per second(b) 262 vibrations per second(c) 524 vibrations per second(d) 786 vibrations per second(e) none of the above(d) 786 vibrations per second
The three characteristics of a musical tone are
loudness, quality, and timbre. The three characteristics of a musical tone are
loudness, quality, and timbre.
(a) True
(b) False(b) False
The wavelength of the fundamental vibration on a l m long string is half as long as the wavelength of the fundamental vibration in a closed organ pipe of l m length.
The wavelength of the fundamental vibration on a l m long string is half as long as the wavelength of the fundamental vibration in a closed organ pipe of l m length.
(a) True
(b) False
(a) True
The ear can “Fourier analyze” a sound wave, but the eye cannot “Fourier analyze” a light wave.
The ear can “Fourier analyze” a sound wave, but the eye cannot “Fourier analyze” a light wave.
(a) True
(b) False
(a) True
If the fundamental frequency of a violin string is 440 Hz, what is the frequency in Hz of the first overtone?
If the fundamental frequency of a violin string is 440 Hz, what is the frequency in Hz of the first overtone?
(a) 1320
(b) 880
(c) 440
(b) 880
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