Conservatoire music students, and a great many other musicians too, will have a well developed sense of relative pitch. This means that given a reference note, other notes can then be named. If students are played a note and told for example, "this is a C sharp", then with "relative pitch" they can tell the name of another note played subsequently. All this requires is:

1. Interval recognition, i.e. what is called relative pitch

2. Some knowledge of music theory related to notes and intervals.

Furthermore, if a reasonable length melody is played on the piano, giving the starting note, they would be able to write down the tune in staff notation, provided the melody is reasonably musically recognizable or memorable as a tune. Again, all this requires is:

1. Interval recognition, i.e. relative pitch

2. Some knowledge of music theory related to notes and intervals

3. Knowledge of writing music and music notation

Some people think they may have perfect pitch because they can sometimes sing a requested note at more or less the correct pitch, or manage to name a note correctly without being first told what it is. You can in fact do this by memorizing or remembering certain pitches. It is true that a music student with perfect pitch would be able to name any given note played on the piano, at any time, without being told the note name first. They would also be able to tell you what key any piece of music is in. But merely being able to do this does not prove you have perfect pitch. Naming notes or keys is not really a definitive test, because with a reasonably memorized reference pitch, other notes or keys can still be named using only relative pitch sense. Also, if you can only recognize certain notes, this is not 'perfect pitch' as musicians and music students would know it. Those with true perfect pitch stand out in a much more decided way.

The instant test

Take a class of conservatoire students and play them a reasonably long melody that is not readily musically recognizable or memorable as a tune, like a random sequence of notes constituting an entirely atonal 'melody', and then ask them to write down the 'melody', without saying what the first note was. Most students will be stumped. But not those with perfect pitch - they will invariably get it 100% right, first time, straight off, with ease. Even if you state what the starting note is, those without perfect pitch are still 'working it out', long after those with perfect pitch have written it straight off, with ease, without having had to 'work it out'.

If you can write music, and would have no trouble with this test, then you do have perfect pitch. If you think you would have trouble with this test, then you do not have the 'perfect pitch' that is known and recognised by professional musicians and music students.

If there's some other standard, then how many standards of 'perfect' are there ?

Why perfect pitch cannot be used to tune pianos 

The 'perfect pitch' ability described above is a real ability, and sets apart those who have it, from those who do not. It certainly has its uses in musicianship. It is not, however, an ability to judge relative pitch differences with any greater degree of accuracy than those without perfect pitch. Musical pitch is popularly supposed to be an objective property of musical sound, but in fact pitch is the sensory response to incoming sound information, not a property of the sound itself. It is subject to physiological and psycho-acoustics factors. Even people with "perfect pitch" often find that their sense of pitch can vary by a semitone or so, if they are unwell. The concept of "accuracy" of pitch is linked to the mistaken idea that pitch is an objective property of sound.

No sense of pitch would be sufficient in itself to successfully tune the piano, because pitch is only one aspect of the sound that is important in the art of tuning. Whilst piano tuners may use pitch sense in part of the tuning process, the greater part of tuning is about tone quality. That is why the tone of a piano after receiving the attention of an expert tuner sounds so much improved.

Tone is linked to pitch, and both are complex, and in part psycho-acoustic, but tone, which is all important, cannot be successfully manipulated just through the sense of pitch.

The sense of pitch depends on the internal structure of a musical tone. The 'pitch' of tones without a suitable internal structure can be very difficult to determine. The dependence of pitch sense on internal (partial) structure also means that aural pitch illusions can be created by manipulating the structure. Two examples of this, showing apparently endlessly rising scales are here.