Hi, i’ve listened many times this frequencies, but yesterday was the first time i realized that the message in the beginning ( “ starting with a tone in the left ear …) was in fact, completely inverted with the headphones. The starting tone in my headphones is in the right ear.  Is that correct??
Likely, you have the headphones on backwards or your device may have switched the channels. As another person said, however, it really doesn't matter. 🙂
Liceu Moletta