170 likes | 184 Views
Sound waves cont'd. Goldstein, pp. 331 – 339 Cook, Chapter 7. Additive synthesis. Fundamental frequency (or first harmonic) : starting frequency for a complex sound Harmonics : pure tones, each of which has a frequency that is a multiple of the fundamental. Fundamental or first harmonic.
E N D
Sound waves cont'd • Goldstein, pp. 331 – 339 • Cook, Chapter 7
Additive synthesis • Fundamental frequency (or first harmonic): starting frequency for a complex sound • Harmonics: pure tones, each of which has a frequency that is a multiple of the fundamental
Fundamental or first harmonic Frequency spectrum frequency: line's position amplitude: line's height Second harmonic Third harmonic
Example • Fundamental or first harmonic: • 220 Hz, given amplitude • Third harmonic: • 660 Hz, 1/3 of amplitude • Fifth harmonic: • 1100 Hz, 1/5 of amplitude • Sum all of three:
12 harmonics • top down • bottom up
Waveforms with 12 equal-amplitude sinusoids using cosine/Schroeder/random phase, at frequencies of 880, 440, 220, 110, 55, and 27.5 Hz
Waveform and amplitude spectra. Periodic waveforms A through D have line spectra, the others either continuous spectra (E and F) or a band spectrum (G).
The width of critical bands as a function of center frequency
Schematic representation of the frequency (heavy lines) corresponding to the tone sensation evoked by the superposition of two pure tones of nearby frequencies f1 and f2 = f1 + f
. All three instruments playing the note G3 with a fundamental frequency of 196 Hz.
DemoMissing fundamental 300 Hz+ 600 Hz + 900 Hz + 1200 Hz 600 Hz + 900 Hz + 1200 Hz
Sound composition and timbre: Helmholtz’s (1863) summary of the various subjective feelings pertaining onthe composition of a complex sound