Re: OT: high-precision tuner app

[Knut Petersen]

Am 23.05.2016 um 19:38 schrieb N. Andrew Walsh:

For whatever reason (or rather: see my previous posts to the list about my interest in just intonation) I'm trying to find a tuning app capable of tuning to very precisely-set reference pitches. That is, when dealing with music in just intonation, it's very common to describe a pitch with something like "C# -49.52c" where the latter part is a deviation in cents from a standard reference pitch (which can also be set as "A440" or some other tuning pitch [which is sometimes necessary when dealing with European orchestras inexorably tuning themselves higher and higher to seem more "flashy" or whatever]). I'm trying to find a (preferably free) Android app that can be set as precisely as possible, and then provide visual feedback to tune my instruments.

Take an excellent grand, tune a' to 440Hz, then tune a'' to 880 Hz with the help of the
best equipment you can find on earth. Play a' and a'' together. It will sound odd,
you'll hear prominent beats of partials no musician would ever accept.

Take the same grand, tune a'' by ear and measure the frequency of a''. Depending on
the instrument you'll measure the fundamental frequency of a'' to be in the range of 880.5 Hz.
That's about a cent to high, according to the theory of tuning based on ideal strings.

Real strings are not mathematically ideal strings. To make things worse: The frequencies
of the partials of a string also depend on the kind of excitement: plugging a string (pizzicato)
results in higher frequencies of the harmonics than bowing the same string.

This is nothing new, if you are really interested in mathematics have a look at 
"The Theory of Sound", written by John William Strutt, Baron Rayleigh, published in 1877.
At least the 2nd edition (1894) is made available by Google.

In 2012 Haye Hinrichsen published an article everybody interested in tuning should read.

After reading that article you'll understand that you do not look for a tuner that helps you to tune
to "C# -49.52c". You need a tuner that helps you to tune to a fundamental frequency that gives
you the sound you expect from a just tuning. But that fundamental frequency is far away from
"C#-49.52c" if your measuring unit is 0.01c. 

Hinrichsen's work also lead to the development of an open source tuning program. There are
versions for Android, IPhone,  Mac OS, Windows, Linux. BUT: This software does not support
historic tunings, although it would be easy to add that feature.


cu,
 Knut