Klarinet Archive - Posting 000543.txt from 2000/08

From: Tony@-----.uk (Tony Pay)
Subj: [kl] The wrong way round, sorry
Date: Sat, 19 Aug 2000 10:06:44 -0400

I've been saying something recently about a difference between playing
in unison with, and alternately with a piano. I just want to 'fess up
that I got it the wrong way round in several of the posts I made about
it.

I wrote in my very first post, for example:

> The overtones [of a piano] are flat to whole number multiples of the
> fundamental frequency, which is what an electronic tuner looks at.

That's completely wrong.

In fact, they are *sharp* to whole number multiples of the fundamental
frequency, particularly in the high register, which means that the
perceived pitch of an 'isolated' piano note is sharper than the
perceived pitch of an 'isolated' clarinet note of the same fundamental
frequency.

By 'isolated' notes, I mean that we're judging the pitch by having the
piano play, then stop; then having the clarinet play then stop; and
adjusting the clarinet pitch until the two instruments sound as though
they are at the same pitch, playing alternately.

To do this, we need to play *sharper* to sound the same pitch as the
piano on isolated notes than we do to sound in tune when we play in
unison with the piano; because when we play *together*, good unison is
judged by our ears to be what gives zero beat frequency between the
fundamentals.

Whereas I wrote, wrongly:

> On the other hand, to play a note so that it sounds the same pitch as
> a high piano, but *after* the piano has sounded, requires a flatter
> pitch than what's required for the unison.

But there's a further ramification. When Bill entered the conversation,
I made the further mistake of confusing this effect with the business of
stretched octaves, which he mentioned.

The way to think about the stretched octaves, which is a way to make the
piano sound in tune *with itself*, is to see that the first partial of
the lower note (which as we said, is slightly sharp to twice the
fundamental frequency of that note) has to correspond to the
*fundamental* of the upper note, because our ear wants zero beat
frequency between these two to judge the octave 'clean'. The further
ramifications of that simple idea (eg, how about double octaves?) was
what David Renaud posted about, but some people may not have followed
the details.

So whereas both effects come about because of the anharmonicity of the
piano sound, they're different.

Summing up: to play in unison with a piano, we need to play sharper high
up, to deal with the stretched octaves.

To play alternately with a piano, we need to play a bit sharper still,
because of the anharmonicity of the string we're playing in unison with.

I'm very sorry about that. I probably confused a lot of other people
while I was confusing myself.

Tony
--
_________ Tony Pay
|ony:-) 79 Southmoor Rd Tony@-----.uk
| |ay Oxford OX2 6RE GMN family artist: www.gmn.com
tel/fax 01865 553339

.... I Have To Stop Now, My Fingers Are Getting Hoarse!

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