Tuesday, December 22, 2009

Checking intonation

With a bit of fussing, I scanned in the etude, so you can look at the notes.
Okay, so how bad is the intonation in it, really? Well, I suppose I could just listen... but I guess I don't have a lot of trust in my ears these days, after all, they were on when I was playing it, and it still ended up how it did. Using the tuner is another way: play it back, and watch the needle. This is helpful, some notes are worse than others. But the tuner takes a few moments to lock on, by which time the music has moved to the next note. So this isn't great either. Besides, it's hard to document and blog about, without making a video, which seems like far too much work.

Other approaches... well, if a tuner can detect intonation, so can a computer. And computers can shift pitch too. Digital pitch correction tools have become an important part of recorded music production in the past decade, particularly in pop music, and we can use this kind of software to analyze the audio in question. First, I tried the "Enhance Tuning" option in Garage Band. Rather than just provide a file 100% corrected, I made of copy of the track, corrected one of them, and played them against each other, so you hear beating on the bad notes.

This is pretty useful, it's easy to hear the notes which have been shifted.
To me, the worst (of many contenders) is the D just before the resolution in bar 8, second time through the first section (start at about 0:54 for the last few notes).

Garage Band, unfortunately, will only fix your pitches, it doesn't (as far as I know) provide a way to look at what it's hearing and doing. I downloaded a demo of Melodyne, one of the heavy hitters of pitch correction, and ran my audio through it. Here's a screen grab of the tail of that phrase. I've selected that D, which is identified as a full 30 cents flat. Making it worse is the note before is sharp, so the interval is pretty close to a full quarter tone off.

So how much does it help? Well, here's a fully tuning corrected version (GB, not Melodyne). To my ear, not much better, which shows that intonation is only one of the problems with how I sound.

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