ETDs and aural checks

[Kent Swafford]

On 1/12/02 8:47 AM, "Clyde Hollinger" <cedel@supernet.com> wrote:

> Friends,
> 
> How many of you ETD users do aural checks?  Isn't that a waste of time,
> if you can trust the ETD?  Or can't they be trusted?  (I'm not giving my
> opinion -- yet, anyway.)
> 
> Clyde

It is not that ETD's are untrustworthy, it is that pianos are untrustworthy.

Modern ETD's are accurate to within +/- 1/100th of a cent. Pianos cannot be
tuned this accurately because pianos do not produce musical tones whose
frequency is as stable as that.

Compared to some other musical instruments the sounding tone of a piano note
is very stable in frequency. However, if you read a piano note with a modern
ETD, you _can_ see ups and downs in the frequency in the ETD display. Such
ups and downs in the visual display can be the result, for example, of
wildness in the string that results in more than one frequency at once
coming from the string that the ETD must try to read at once. This means
that the frequency display of the ETD needs to be interpreted by the
intelligence of a human. The wildness can be so much that the display is
rendered beyond interpretation, as in the example given by Ed Foote of the
note that simply must be tuned aurally instead of visually. Many notes will
yield a _little_ uncertainty that will be in need of a little
interpretation.

I suspect when techs say they don't listen at all when tuning with an
ETD, there is an assumption that this is a piano that they have tuned many
times, that the piano is very clean-tuning, and that the tech has a
standard, consistent, practiced way of interpreting the ups and downs of the
frequency display.

The interpretation necessary when tuning a piano string to an ETD display is
a common potential source of inaccuracy in tuning, and is a reason why aural
checks are mostly always necessary.

If you do your best aural tuning and record the tuning to an ETD and then at
some future time use the stored tuning to tune the same piano again, is the
result an aural tuning, or a visual one? If you didn't listen, I say the
tuning is a visual one. All tuning done with an ETD should be subject to
aural verification.

Kent Swafford