I don’t have perfect pitch. Well, I have one–concert Bb. It’s generally one of the first notes I play every time I pick up a trumpet. How many times have I played the tuning note for a wind ensemble? It’s the central note in any bugle work. I know this note.
If I need to identify a pitch by ear, I call the Bb into mind and see what the interval is. I rarely miss. Mom sings in a choir where the director has them start by singing 440 out of nothing. They do fairly well. There may be one or two people out of the 100 with perfect pitch, but all of them are learning a home note like I have. I’m sure any violinist and pretty much any oboe player could do the same with A.
But there’s a lot more to how we know a note than having the pitch in mind. When I imagine the note, although I’m just trying to recall the frequency, I recall the tone: I couldn’t get it right imagining it on a piano. I’m also thinking about the attack and the sustain, because I play the tuning note differently than I play most other notes (even the same Bb in a different context): no vibrato, confident but moderate attack and volume, right hand relaxed. The combination of all these somatic variables helps me isolate the right memory.
The open note feels different on the horn than any of the fingered notes, and the tuning Bb is the midpoint of the range (at any rate of the range I usually use). Of all notes on the horn, it’s the one requiring the least adjustment, the one that settles most accurately into itself regardless of whether you approach it from above or below, near or far. It’s in a range where the weak third finger is not used in the primary fingerings but the overtones are not so close together that one is easily mistaken for another.
So I know that note very well. I have studied the note beyond trumpet. My voice usually breaks at B, so I can add that to my internal Bb (found next to the kilogram in Sèvres, in my mind at least) to see where I am. From playing harmony with other instruments, I have a sense of how they play Bb, what register it’s in for them, whether it’s a ground key (for almost all winds, it is; for almost all strings, it isn’t). On piano and guitar I live in the native key centers, but there’s always a click in my mind when I go to Bb.
Given that, I learn the most about the different ways to play a note by playing that note in different ways. When I learned how to do flutter-tonguing, and as I’m learning to play double notes, Bb is the simplest case where all other complexities are set aside. When I need to practice vibrato, lack of vibrato, dynamic extremes, mute techniques, or anything else, it’s the note I use to focus on that one aspect.
That’s as much as I know about a note. There may be other things to say about a key, but that’s the standard by which I measure the characteristics of a note.