Sound is a phenomenon wrought with ambiguity. It is the sensation of sound which most of us are concerned with when we play or listen to music. Our knowledge of sound is generally speaking divided into:

  1. subjective perception of music and noise.
  2. the attempt to analyze, measure and classify the physical characteristics of vibrational systems.

People have had the tendency to distinguish musical sounds from unmusical sounds. Musical sounds have been defined as those which are smooth, regular, pleasant and of definite pitch, and unmusical sounds have been those which are rough, irregular, unpleasant and of no definite pitch. This can only be an approximate classification since many sounds which pass as noises have associated musical notes and almost all musical notes have associated noises.

The source of a musical note is always some "system" in vibration. It can be a stretched string as in the violin, a column of air as in a flute or organ or a bent rod as in a tuning fork. These vibrations communicate themselves to the air surrounding the vibrating source and are transported from the source of sound through the air to the ear of the listener. From the physical point of view we can consider three aspects of a musical note:

  1. The source in vibration.
  2. Transmission through the air.
  3. Reception by the hearer.
The nature of sound makes it difficult for a scientist not to deviate from pure physics into psychology, aesthetics, physiology and anatomy. The fact that sound is governed by laws of wave motion and therefore being the subject of time-space, relates it to the study of particle physics and the borders between physics and philosophy are often rather blurred.

But thinking about sound as we hear it, Samuel Clements alias Mark Twain, said "Wagner´s music is better than it sounds" finding it a bit cranial. But most of us can easily distinguish an awful violin from a great instrument, and the ability to hear the qualitative difference between a good violin and a masterpiece really calls for the expertise of the experienced player, maker and listener. Nonetheless most people can recognize individual voices over low-tech telephone equipment, even very similar voices. The human ear is a miraculous piece of equipment. The fact that we can hear most of the distinguishing characteristics of a double bass through a tiny transistor radio with a 2 inch speaker is fascinating. The small speaker can in no way reproduce the low frequencies of the bass. This is where the ear comes in. The ear and the peculiar way in which it is linked to the perceptive regions of the brain has the amazing capabilty of actually adding the low notes of the bass to the physical sound which we hear from the tiny speaker, deducing them from the scant information at hand. This is the realm of psycho-acoustics.


An interesting analogy to this is a perhaps a similar phenomenon in visual terms is this image:

If it were not for the fact that our minds/brains have since an early age been compiling a huge database of visual impressions, we might not be able to recognize a dalmatian dog on a cobblestone pavement in this highly graphic image.