MUS 105 - Basic Musical Acoustics

sound

small fluctuations of air pressure

noise

nonrepeating variations in air pressure

fundamental frequency

reciprocal of the period; number of repititions of pattern occur per unit time

transposition

changing fundamental frequencies in a way that preserves their ratios

wavelength

length of the repeating pattern; inversely proportion to frequency

wavelengths and frequencies for high and low notes

high: small wavelengths, more repetitions

low sounds: large wavelengths; fewer repeititions

octave

2:1

perfect fifth

3:2

perfect fourth

4:3

major third

5:4

minor third

6:5

two fifths above x

(3/2)(3/2)x

consonance

chords that sound stable and restful; aligned or distanced overtones

dissonance

chords that sound unstable and active; clustered or misaligned overtones; also depends on volume, internal sound of instrument

overtones/partials/harmonics

periodic function as the sum of sine waves with frequencies that are integer multiples of the fundamental frequency

when are pairs of harmonic tones consonant

when their fundamental frequencies are simple whole-number ratios

overtones of most Western instruments

f, 2f, 3f, 4f

comparison of overtones between low notes and high notes

low notes have more overtones

minor sixth

8:5

major sixth

5:3 (10:6)