Hearing Figure 4.5 An artificial arrangement causing 200 Hz to be heard, but where the 200 Hz tone, if
present, would not be discernible due to heavy masking noise.
t4=tonegen(196*4, 8000, 2);
and then we will simply play back these, firstly a pure G 3
. Remember the pitch of this
tone, then we will play back the complex note both with and without the fundamental:
soundsc(t1, 8000);
soundsc(t1+t2+t3+t4, 8000);
soundsc(t2+t3+t4, 8000);
It should be noticeable that although the quality of the sound differs somewhat, the
musical note being replayed is the same in each case.
Musically speaking, the fundamental frequency is the perceived note being played.
Harmonics and other tones may be present, with timbre or quality changing greatly
depending on the proportions. This is one of the defining characteristics of different
musical instruments. Even when low frequency noise masks the perceived note (the
residue frequency) such that it cannot be heard, the frequency of the residue is still
perceived [17]. This is demonstrated in Figure 4.5, where the tones shown would evoke
a response at 200 Hz, a frequency that if really present at that volume would be swamped
by noise.
We find that both arithmetic and geometric relationships of single tones are discerned
by the ear as being composite in some way.
4.2. Psychoacoustics 69
Table 4.1. Binaural masking conditions and features (constructed from data presented
in [18]).
Noise condition
Signal condition
Processing gain
in phase
in phase
0 dB (reference condition)
uncorrelated
out of phase
3 dB
uncorrelated
in phase
4 dB
out of phase
in phase
6–13 dB
in phase
out of phase
9–15 dB
