About pitch less than a half tone

Hi folks,
I’m using Audacity 2.1.2 both on Ubuntu Linux (17.04) and Windows 10.
Often I change tune of a music downloaded to make it easy for my student (I teach blues harp in a Music school).
Recently I need to tune a song less than an half tone, because I found the original song is in the right key, but low about 10-15 Hz.
So, I found the right tune after a lot of trials: is there a fast and better method to do this?

Were you using the Preview button in the change pitch effect? I generally find that a bit quicker than “apply → undo → apply a bit different → undo ->…”

Yes, sure, but I’m looking for a method to precisely find the real tune… Is there a method or the only way is to proceed for trials?

There’s a plug-in here that is pretty good at finding the pitch of a single note: http://wiki.audacityteam.org/wiki/Nyquist_Analyze_Plug-ins#Pitch_Detect
Installation instructions are here: http://wiki.audacityteam.org/wiki/Download_Nyquist_Plug-ins#install

I placed the file in the folder you suggested; save the change; close Audacity, re-open it: the EFFECT list doesn’t contain the new plug in.
How can I solve?

You have to click on the Enable button, then the OK button below it, before the effect appears on the effects list …


Thanks Trebor, but as soon as pressed “Submit” to send my message, I found the solution. Sure, I already enabled the plug in, but it appears in “Analyze” menu and not in “Effect”.
Thanks again to all