Piano Tuning » Methods of Traditional Piano Tuning
Methods of Traditional Piano Tuning
Let's assume that these things are in relatively good working order, now we can proceed to discuss the matter of Tuning. On the subject of Tuning, I again refer to The Musician's Guide to Acoustics, Campbell and Greated, p. 252 ff. which gives a good overview of the two aspects of basic tuning technique:
First is the traditional "laying the bearings" or setting a central octave in proper pitch using the time-honored methods which involve attending to the "beats" or pulsations of amplitude (loudness) which accompany two sounds which are being tuned to the piano's Equal Temperament system. This system has faults, but it allows you to play in all keys equally (C and G, p 178 ff.)
Piano technicians who do tuning listen to these beats, not to the pitches the way musicians do, and base their tuning on their sense of the proper beat/ratios for each note being tuned. This is a complicated process which involves actual beat/ratios like. 89 and 10.37, which the tuner perceives through experience, since he can not actually count beats to two decimals accuracy. In fact he checks the sounds continually by sounding thirds and their inverse, the sixths, which tell the ear quickly if something is far wrong. But these thirds/sixths relationships become faster and faster as you go up the scales, so here again is a perceptual rather than a factual, mathematical relationship.
Second is the matter of stretching the bass sounds downwards and the treble sounds upwards, a matter which is dependent partly on human acoustic perception, but even more on complex properties inherent in the structure of the piano. Suffice it to say that the strings must be "stretched" correctly for a given piano, or you will hear errors as soon as you play. The tuner knows this by ear and experience, you normally trust his judgment, and the good sounding result marks a first-class tuner and his work.