Knowing that there are several types of octaves, different aural tests are necessary to ensure that the appropriate type is being tuned in a given area of the piano. Since only one type is in tune at a time, and so rare is the exception, the tests for one type only should be used at a time. The exception, of course, would be in a transitional area, changing from one type to another.

Two different aural tests have been provided so that the findings may be double checked. Since the aural tests employ the use of intervals for comparison, both expanded and contracted, and either the upper note or lower may be the reference to which we are tuning, four classifications of aural tests result. Be sure to note the Classification for each test so as to correctly interpret the findings and make the proper adjustments in tuning the octave.

CLASS A: Lower note is the reference note. If the beat rate between the test note and the upper note is too slow as compared to the beat rate of the test note and
the reference note, raise the upper note. If the beat rate with the upper note is too fast, lower the upper note.

CLASS B: Upper note is the reference note. If the beat rate between the test note and the lower note is too slow as compared to the beat rate of the test note and
the reference note, raise the lower note. If the beat rate with the lower note is too fast, lower the lower note.

CLASS C: Lower note is the reference note. If the beat rate between the test note and the upper note is too slow as compared to the beat rate of the test note and
the reference note, lower the upper note. If the beat rate with the upper note is too fast, raise the upper note.

CLASS D: Upper note is the reference note. If the beat rate between the test note and the lower note is too slow as compared to the beat rate of the test note and
the reference note, lower the lower note. If the beat rate with the lower note is too fast, raise the lower note.

The object in each case is to obtain an equal beat rate between the upper and lower notes of the octave, and the test note. Each test is given a name corresponding
to the intervals employed in the test. In naming the intervals, "P" denotes a so-called "Perfect" interval, "M" denotes a "Major" interval, "m" denotes a minor interval,
"A" denotes an "Augmented" interval, and "d" denotes a "diminished" interval. It must be noted that some of these intervals are very hard to hear in the bass region of
the piano. These checks, however, are still valid. To make use of these checks, hold down one of the octave notes and the test note without playing them. (You may
have to use the sostenuto pedal in some cases.) Play the strike note with a staccato blow. Repeat this procedure with the other octave note and the test note. When
the two beat rates are the same, the type of octave which has been tested for will have been tuned. The strike note in all cases is the note listed in the electronic
setting instructions for that particular type of octave.