Re: [Harp-L] tune the higher notes sharper or lower?

[The Iceman <icemanle@xxxxxxx>]

If you don't push the higher octaves on a piano a bit sharp (stretching), the human ear tends to "hear" these as being on the flat side, even though, in a textbook sense, they are tuned at proper pitch. Stretching the tuning as you go up into the higher range compensates.


The stiffness in the strings as described by Richard effects the partials of the string. We hear the fundamental tone mixed with the upper harmonics as a single note. There is a mathematical relationship between the two that gives the best note to our ears - based on a formula that looks good in the lab but frequently does not exist in reality. The partials move away from this formula in piano strings because stiffness of the string will shorten the vibrating length. This small change is not so apparent in the fundamental and lowest partials, as it is a small percentage change in relationship to the whole. As higher partials are formed, the vibrating string length becomes much shorter, so a small difference becomes a larger % of the overall length, hence moving the actual breakdown in numbers for this relationship away from the smooth and acceptable numbers in the formula. 


A tuner's talent lies in recognizing all of this and compensating with constant compromises in order to create the "least of all evils" final product.


In harmonicas, I do not stretch the tuning going up. I prefer that the octaves sound pure and beat less - not the best arrangement for that dirty blues sound, but more suited to my sensibilities.





-----Original Message-----
From: Richard Hunter <turtlehill@xxxxxxxxxxxxx>
To: harp-l <harp-l@xxxxxxxxxx>
Sent: Mon, Jul 4, 2011 4:27 am
Subject: Re: [Harp-L] tune the higher notes sharper or lower?


The Iceman wrote:
<human ear can not determine a difference in tones until they are at least 3 
cents apart. this is based on info <I learned as a piano tuner and based on 
laboratory type testing.

I used to tune pianos for a living.  The reason some piano tuners use a 
"stretch" tuning (meaning a tuning with the upper octaves tuned slightly above 
pitch) is that piano strings exhibit a phenomenon known as "inharmonicity," in 
which the stiffness of the string inhibits vibration of the normal harmonic 
nodes on the string, making it sound out of tune.  This effect is pronounced on 
the highest notes on the keyboard, where the strings are very short and under a 
lot of stress.  (It's also an issue on bass strings, especially when the piano 
is small, meaning that the bass strings are relatively short.)

Harmonicas are not subject to this phenomenon, because harmonica aren't stringed 
instruments.  So I don't see a lot of value in tuning the upper register notes 
sharp. 

As per previous comment, it might be useful to tune lower notes on the harmonica 
up to account for the flattening in pitch that occurs when those notes are 
played hard.  But I wonder what the chords will sound like afterwards.

Regards, RIchard Hunter




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