Beautiful music is capable of reaching deeply into our souls, imparting peace and tranquility .There is something satisfying about musical sounds that blend and harmonize. Some combinations of sounds, however, are anything but pleasant to our ears.
We are going to examine some of the characteristics of our ear/brain hearing system to find out why some intervals sound lovely, and some sound raucous and unpleasant.
Music involves such highly complex sounds that one tends to be overwhelmed when trying to analyze just what is going on. For this reason, we must once more fall back on pure tones as we probe into the question of why some tonal combinations sound good and some do not. We shall base this exercise on a tone of 500 Hertz at a comfortable listening level:
We are now going to add a second tone, an identical 500 Hertz of the same amplitude:
Notice that there is considerable increase in loudness because the two sine waves have a time relationship described as being "in phase."
Because the two tones are in phase, they add constructively and the resulting combination has twice the amplitude of either tone alone. Those knowledgeable in electronics will recognize this as producing a 6 decibel increase in signal level.