Hi all, Pitch drop over time. Pitch drop due to humidity. How do we decide which is which? This morning one of my "faithful" clients had me tune her piano. History: 1992 01 pitch corrected 92 cents at A4 humidity 40% (including overpull) 1992 02 floated pitch at 7.5 cents sharp at A4 humidity 47% Today? Pitch correction at A4 of 31.6 cents and worst note of 120 cents humidity 29% (including over pull). Total pitch change over 160 months at A4 = 39.1 cents My "guestimate" is that for every 5% humidity change A4 drifts 4 cents. This would give around 14 cents of the pitch change for the humidity portion. Plugging that value in makes the pitch correction at A4 more like 25 cents in a mere 160 months between tunings, or about 0.15 of one cent per month. I have no way to factor in humidity change for the worst note but if we ignore it then 120/160 =~ 0.75 cents per month. I hope more folks will do this sort of analysis and post it to the list--I found Conrad's data *most* interesting! Particularly that the piano was at 436.7 on 01/03 and a year later was 436.7 again. Too bad there was no measurement of room humidity to go with this! Regards, Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T. Non calor sed umor est qui nobis incommodat mailto:pianotuna@yahoo.com http://us.geocities.com/drpt1948/ 3004 Grant Rd. REGINA, SK, S4S 5G7 306-352-3620 or 1-888-29t-uner
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