False beats Mystery

[Thomas D. Seay, III]

>I am tuning a good quality grand.  The bass section goes fine but about
>C5 I notice an increasing amount of false beating in EVERY note.  The
>higher in the scale I go the harder it is to tune because the true
>beating is getting buried under the false.  What is my problem?
>
>Clue #1  The problem probably only occurs in the Southern areas.
>
>Clue #2  The smaller the room, the more pronouced the false beating
>becomes.
>
>Have fun!
>
>Warren

Ceiling fans?

Tom Seay
School of Music
The University of Texas at Austin