Page 41 - The Master Handbook Of Acoustics
P. 41
16 CHAPTER ONE
f 1
Amplitude
0 A
Time
f 2
0 B
f 1 f 2
0 C
f 3
0 D
f 1 f 2 f 3
0 E
FIGURE 1-13
A study of the combination of sine waves that are not in phase. (A) The fundamen-
tal of frequency f . (B) The second harmonic f with twice the frequency and half the
1 2
amplitude of f advanced 90 degrees with respect to f . (C) The combination of f and
1 1 1
f obtained by adding ordinates point by point. (D) The third harmonic f with phase
2 3
90 degrees behind f , and with half the amplitude of f . (E) The sum of f , f , and f .
1 1 1 2 3
Compare this waveshape with that of Fig. 1-11(E). The difference in waveshapes
is due entirely to the shifting of the phase of the harmonics with respect to the
fundamental.
