# Can people with absolute pitch identify the exact frequency, or simply the pitch class?

Absolute pitch can be defined as the ability to identify or re-create a given musical note without the benefit of a reference tone.

When people claim to have absolute pitch, does this mean they have the capacity to detect the exact frequency of a note, or merely the pitch class (i.e. C,C#,D, etc)?

• Given the answers and comments below, we had some difficulty understanding what you exactly mean with absolute pitch. The definition I used as obtained from two review articles corresponds well with the wiki page: en.wikipedia.org/wiki/Absolute_pitch. Assuming we are on the same page, I have added the definition from the wiki page in your question to clarify the question. Please feel free to roll back
– AliceD
Commented Aug 24, 2015 at 1:54
• Thanks @AliceD! I thought about it and I think this looks like it will help the thread a lot. It was definitely too vague before. Commented Aug 24, 2015 at 2:34
• Quite frankly it was perfectly clear to me, but when I saw the other answers I started doubting my interpretation. Anyway, now it is made explicit.
– AliceD
Commented Aug 24, 2015 at 2:45
• I interpret this as meaning: can a person with absolute pitch be able to say: "This orchestra is tuned one/two/three notches higher/lower than my orchestra" where the notches correspond to the acceptable range for, say, an A (438-445Hz). No one would expect granularity down to the individual hertz level (maybe?!) but I would think true absolute pitch allows one to tell apart a 438 from a 442 from a 446Hz A. Using my digital tuner, I could easily tell hear the relative pitch change as I adjusted as little as 1Hz at a time. Commented Jul 9, 2019 at 0:42

In practice, absolute pitch is generally tested for by using musical pitch classes.

Background
Absolute pitch (AP) is the ability to identify the pitch of a musical tone, or to produce a musical tone at a given pitch without the use of an external reference pitch. Most humans process musical pitch relatively rather than absolutely, and in fact most sensory systems operate relatively and not absolutely. AP is indeed a rare ability, occurring in less than 0.01% of the general population (Tekuechi & Hulse, 1993).

The way in which AP is tested is mostly using pitch classes. Pitch classes are likely preferably used experimentally, because people with AP are often musicians. Musicians are already familiar with pitch classes because of their training. In turn, AP typically manifests itself in trained musicians (Zatorre, 2003). Therefore, testing AP using frequencies expressed in Herz may simply be too abstract for most people with AP, since they are more accustomed to the use of pitch classes.

Note that, because the pitch A4 used to tune orchestras, corresponds to 440.0 Hz by modern convention, AP as tested with pitch classes can be, indirectly, considered to represent frequencies.

Some subjects with AP may consistently identify pitches a semitone low or a semitone high. This can occur because a subject may be accustomed to a different tuning standard for A4 than 440.0 Hz (Tekuechi & Hulse, 1993). Hence, AP has a strong correlate to training.

References
- Tekuechi & Hulse, Psychol Bull (1993); 113(2): 345-61
- Zatorre, Nature Neurosci (2003); 6(7): 692-5

• @StanShunpike - thanks :) Corrected
– AliceD
Commented Aug 24, 2015 at 2:43

It can be either, and is typically both, considering that

Absolute pitch is an act of cognition, needing memory of the frequency, a label for the frequency (such as "B-flat"), and exposure to the range of sound encompassed by that categorical label.

Another way to look at it is that pitch class came from the necessary assessment and organization of pitch frequency, similar to how symbols such as letters came from our assessment of different phonemes. So the ability to detect one usually implicates the detection of the other, and we call this ability 'absolute pitch'.

• @AliceD I was under the impression that the ability to detect an exact frequency allows one to "label" that frequency with its associated pitch class, much like the recognition of how a word 'sounds' might allow you to spell the word. I interpreted the OP to be referring to one's ability to detect a frequency to the point where they could recognize its pitch. I think that you interpreted it as the ability to detect a frequency and name that frequency in Herz, which may have been the correct way to interpret the question. Either way, that was what I was referring to in my answer. Commented Aug 23, 2015 at 17:48
• Thanks for explaining. I am however not implying that folks can name the frequencies in Hz.
– AliceD
Commented Aug 23, 2015 at 22:03
• +1 for defining which processes are needed in pitch labeling.
– AliceD
Commented Aug 24, 2015 at 13:01