Unison coupling

[J Patrick Draine]

>>> >>The frequency of vibrating piano strings is not stable, but
>>tends to
>>> >>lower as the string continues to sound.
>>I would like to see a reference to support this.
>
>* Don't need one, you can verify it for yourself. I seem to remember you
>saying you had a SAT, is that right? If you do, try it out at your next
>tuning. Note the pitch in the first half second or so of the attack, and
>the drop in pitch as the note continues to sound. The pitch drop isn't at
>the same rate through he duration of the sound, but is most rapid
>immediately after attack, and continues at a diminishing rate until it

It's also pretty obvious to your own ears after one sees it verified by the
SAT.

Patrick