1. Chapter 21
Musical Sounds

2. Three characteristics of a musical tone:
1. NOISE VERSUS MUSIC
Wham - Noise and Wave Forms
Three characteristics of a musical tone:
Pitch
Loudness
Quality

3. 2. 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.

4. Change pitch by altering the vibrating source.
Response to high pitch usually declines with age.

5. 3. SOUND INTENSITY AND LOUDNESS
refers to pressure variations
Intensity is directly proportional to the pressure amplitude squared.
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.

6. Loudness b = 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 different frequencies.

7. Common Sound Intensities

8. Response of the Ear at Constant Loudness

9. 4. 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.

10. Same Note - Different Instrument

11. Human Voice

12. Harmonics 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.

13. Adding Harmonics
1st
2nd
Sum

14. Demo - Harmonics on a Guitar
Demo - Organ Pipe

15. Speaker Shortcomings
The brain can fill in missing lower harmonics that small speakers cannot create.

16. 5. MUSICAL INSTRUMENTS Three basic types
stringed, air column, and percussion
Because of energy loss, string sections in orchestras are generally larger.
Electronic

17. 6. 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.

18. Adding Harmonics
Spreadsheet

19. 7. COMPACT DISCS Phonograph players give analog signals.
Digital signal is in binary code.
CD has flats and pits and is sampled 44,100 times per second.

20. Diatonic C Major Scale Letter Frequency Frequency
Note Name (Hz) ratio Interval
do C
9/ Whole
re D
10/ Whole
mi E
16/ Half
fa F
9/ Whole
sol G
10/ Whole
la A
ti B
do C

22. Chapter 21 Review Questions

23. The quality of a musical note can be changed by simply playing the note on a different instrument.
(a) True
(a) True
(b) False

24. 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

25. The three characteristics of a musical tone are loudness, quality, and timbre.
(a) True
(b) False
(b) False

26. 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
(a) True
(b) False

27. The ear can “Fourier analyze” a sound wave, but the eye cannot “Fourier analyze” a light wave.
(a) True
(a) True
(b) False

28. 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