Audio Engineering

6 Chapter 1

1.4 Sound and the Ear ......................................................................................................

Experiments can tell us that the ear only responds to a certain range of frequencies
within a certain range of levels. If sound is defi ned to fall within those ranges, then
its reproduction is easier because it is only necessary to reproduce those levels and
frequencies that the ear can detect.

Psychoacoustics can describe how our hearing has fi nite resolution in both time and
frequency domains such that what we perceive is an inexact impression. Some aspects

Level

Waveform

(a)

Frequency

Spectrum

fo 3 fo 5 fo 7 fo 9 fo

Waveform

(b)

Level

‘White’ noise

Spectrum Frequency

Figure 1.3 : (a) A periodic signal repeats after a fi xed time and has a simple spectrum

consisting of fundamental plus harmonics. (b) An aperiodic signal such as noise does not

repeat and has a continuous spectrum. (c) A transient contains an anharmonic spectrum.

(c)

Waveform

Level

Spectrum Frequency