Drifting Unisons

[Fred S. Sturm]

Ron Nossaman wrote:

> A major humidity drop should reverse the
> patterns as compared to a major rise. I don't think you indicated what you
> find when the humidity is high and you have to drop pitch, did you? Are the
> patterns reversed?

Yes. Right string generally sharpest after pitch rise due to rise in 
humidity. Right string generally lowest after pitch drop due to drop in 
humidity. More prominent in grands than uprights (I think), but the same 
pattern usually in uprights (right string goes farthest in whatever 
direction). Caveat: there are a lot of exceptions within individual 
pianos, and between one piano and the next. It <seems> to be a pattern. 
To confirm that it really is would require long term recorded 
observation. But I have been noticing and making mental (and sometimes 
sketchy written) notes for 15 years now, and it appears to be the 
prevalent pattern. It may be less noticeable to me in uprights since I 
tune them less often, hence more of a chance that there have been 
several intervening humidity spikes in both directions, clouding the 
evidence.

> This is interesting, and we may pin a plausible cause
> and effect relationship on it yet. If not, we're at least taking up
> valuable  space and making thinking noises, so it's not altogether wasted.
> 
> Ron N

Gotta think of something while repeating a process for the umpteen 
thousandth time. Keeps the juices flowing, maintains flexibility of the 
thought processes.
- Fred