As the art of music developed through the ages it came to be accepted that notes of certain frequency relationships gave a pleasing result when played together, while others produced a harsh effect. This experience led to the establishment of musical scales consisting of a series of notes whose pitch relationships enabled the maximum number of pleasing combinations to be obtained.
Music evolved along various lines in different parts of the world, and scales were adopted which differed both in the number as well as the pitch of the notes they contained. From the middle of the sixteenth to the middle of the nineteenth centuries European music, in particular, came to be based on the diatonic scale. This consists of eight notes which may be represented in various forms of notation (Fig. 28.2).
For scientific purposes, the diatonic scale has been standardized as a series of notes ranging from middle C (c’), 256 Hz to upper C (c”), 512 Hz. Most of the
tuning-forks found in laboratories are in scientific pitch, but these are nsuitable for tuning musical instruments, as will be explained in due course. At the outset it must be understood that, as far as music is concerned, the actual
pitch of the notes has never been regarded as being so important as the ratio of the pitches of the various notes of the scale. Thus, during the eighteenth century it would be rare to find two organs whose middle C pipes had the same frequency, although, of course, the ratio of the pitches of the different pipes would be substantially the same for all instruments. However, with the development of orchestral music, attempts were made at arious times to establish a uniformity of pitch acceptable to musicians in all countries. In the year 1939 an international committee agreed that standard musical pitch should be based on a frequency of 440 Hz for a’.