Behavior: Basic Psychology of the User - Foundations for Designing User-Centered Systems - page 104

Fig. 4.16 An example waveform from audacity

Fig. 4.17 Example,
simplistic, Fourier analysis
that might match the
waveform in Fig. 4.16

10

9

8

7

6

5

4

3

2

1

0

10 100 1,000 10,000

Frequency (Hz)

Waveforms with a single sine wave sound purer. Waveforms with different
combinations of frequencies sound different. How many of these subwaves there
are determine whether you are hearing a piano or an organ, or Frank or Gordon
speaking.
Loudness of the sensation is largely dependent on the amplitude of the wave.
However, the ear is not equally sensitive to all frequencies, so sounds at different
pitches will not have the same loudness. The pitch of the tone depends primarily
on the frequency of the sine wave, but not completely. Pitch is also dependent on
amplitude. The apparent pitch of high frequency tones will increase with
increasing amplitude but the apparent pitch of low tones decreases with increasing
intensity. The loudness of a tone will also depend on the phase relationships of the
component frequencies of the stimulus (that is, do they all start at once or do they
start after each other but offset in time). Timbre is a quality that depends on the