This is really strange and I cannot figure it out. I had an MP3 file that I put into audacity and changed the key (moved the pitch up from E major to G major). I then exported this file as a new MP3, and this new MP3 plays in the higher key (G major) on my computer (windows based) and my iPhone (I use good reader on my iPhone to play it).
But when I play this new MP3 on my singing teacher’s Mac, it plays in the original lower key of E major. I both emailed her this new MP3 and used a copy on a USB, and both times the song played in the original lower key (E major) on her Mac. I took the USB home and played the same track on my computer again (thinking I must have somehow saved the wrong file to the USB) and it played in the higher pitch (G major) on my computer! What is going on??? Has anyone had this problem? I hope this makes sense.
The clocks (oscillators) in the different soundcards PROBABLY don’t match. That’s the clock that generates the 44.1kHz sample rate (or whatever sample rate you’re using) is off. That will affect the speed/tempo and pitch together like playing a vinyl record at the wrong speed.
That’s not an unusual problem with “consumer soundcards” but it’s usually not THAT bad! It’s usually a “half step” or less.
…The odds are it’s not exactly on-key in E major. It’s more likely to be a “random” pitch shift.
If you record and play-back on the same setup you won’t know there’s a problem. And unless you are musician trying to play in-tune you usually don’t hear the difference and you won’t hear anything wrong with MP3s or streaming music, etc.
No clock is perfect (1) but since your iPhone and your computer are the same the teacher’s Mac is most-likely the main problem. Audio interfaces (example) are usually MUCH better.
Another more rare problem is for 44.1kHz and 48kHz to get mixed-up. That’s a difference of about 8% which is a little more than a half-step
(1) Pros often use an expensive master clock (sometimes called a “word clock”) along with interfaces that have an external clock input. Sometimes it’s an atomic clock. And with a master clock multiple devices can “locked-together” down to the exact sample.
Thank you so much for this answer. That’s it!
I apologize but the actual pitch shift was from G flat (not E major) to G major. I just didn’t think anyone would believe that I could hear the difference in a semitone and would blame my ears for the mistake. So I wrote E major (the song was Born to Run, Springsteen - originally in E major which I moved to Gflat. And after a week of practice on G flat decided to move up a semitone to G. But I used the G flat file and changed that to G major).
Your answer sounds spot on for my problem. Thank you for taking the time to answer.
From now on, if I need to adjust a backing track by a semitone or even 2 semitones, I’m just going to bring my guitar and play instead.
It’s not an even number of semitones. You might have to change it by some random percentage.
Does that mean you’re going to re-tune (or “de-tune”) your guitar?
If so you can use Audacity to generate an A=440Hz (or another note-frequency if it’s more convenient for guitar tuning). That will be “digitally perfect” and you can blame any error on the computer hardware.
That way to you tune to whatever computer you’re using at the time.
Of course SOME commercial music is pitch-shifted (accidentally or intentionally) and occasionally someone will use A=430Hz tuning. But the vast majority of music is tuned “correctly”. I read about a Beatles song where they wanted to change the tempo and with analog tape you can’t change one without the other and it’s not tuned to any normal key.
P.S.
I just had another idea… You can get a cheapo USB soundcard… (Of course it doesn’t have to be cheap but you can get them for almost nothing.) You can use it on your computer and your teacher’s computer. The odds are that it will be better, but even if it’s not better it will be consistent on your computer and her computer.