Can you elaborate on that? One thing that I noticed is that sometimes it can be hard to make the black keys sound the same as the white keys just because of their different geometry. They are shorter and therefore the lever length is shorter. You have to actively work to get timing and intensity right but you learn that early.
Apart from that I cannot think of a reason why they should be different from the white keys.
However, I can definitely tell a difference, and it’s not subtle at all. If you play a note on the piano for me while my eyes are closed I can reliably tell whether it’s a black key or a white key. If I’m playing on a (high-quality sampled) synth piano that’s accidentally set to transpose -1 or +1 semitones I notice right away that it sounds like a black key where I played a white key or vice versa. Something about the black keys seems to sound a bit harsher/sharper/tangier to my ears; maybe a slightly sharper attack and/or slightly brighter harmonics in the upper-mid range.
I suppose it’s possible that I’ve just learned to distinguish the pitches — I don’t have perfect pitch, but I’ve been playing piano for quite literally longer than I remember, so maybe my brain just internalized the C major scale, or something. But I’m sure I can hear a difference :)
Which keyboard/samples do you use where the difference is not subtle? I'd like to do the black key vs. white key test without looking. Maybe there is something to it I'd never noticed.
Of course, since you hear this effect even when played one by one, this assumes you are unconciously comparing them to some reference pitch. (I'm not aware of anything in manifacturing of piano strings that would somehow make black strings be produced different, so unless I'm missing something, it would have to either be in terms of key mechanics, hammer wear, or tuning.)
I also do not know the reason, but I suspect it might have to do with body resonances/geometry.
> the black keys on a piano sound distinctly different than the white keys
I never noticed that and it doesn't seem plausible to me. The mechanics of black and white keys are identical, no?
And of course, playing a song in a higher or lower key means you’re playing it higher or lower. A couple semitones can make a subtle difference in the character of a piece; transposing half an octave can be drastic. This combines with instrument-specific differences too, as most instruments just sound different in different octave ranges. I once had to play a piece written that was written originally in A major for a Rhodes electric piano, but I had to transpose to D major to accommodate a vocalist. This was incredibly awkward; transposing downwards sounded way too muddy, but transposing upwards sounded annoyingly chimes.