The notes on musical instruments are organized into scales and we would like to have a scale where we get the greatest number of combinations that sound good together. We also would like to standardiz...The notes on musical instruments are organized into scales and we would like to have a scale where we get the greatest number of combinations that sound good together. We also would like to standardize the scale in such a way that if we build other instruments, two instruments playing together can play the same pitch. This turns out to be more difficult than it would seem. The choice of scale is arbitrary and different cultures have chosen differently.