Some people have noticed that when they're listening to music through headphones and they yawn, the music slows way down. This might be due to a little thing called chronostasis.
A few days ago we looked at the Stopped Clock Illusion, when the the second hand of the clock freezes for a bit the moment you glance at the clockface. One commenter mentioned that they noticed a similar thing happening when they yawned while they were listening to music. I looked around and found that plenty of people experience this, but don't know exactly why. It could be related to the Stopped Clock Illusion, in the sense that both are forms of chronostasis. Chronostasis happens whenever a shift in attention causes the brain to draw a moment out. Clocks are easy to "stop", but one research team tried an experiment to see if chronostasis was a strictly visual phenomenon or if the other senses could get involved.
Volunteers were asked to put on headphones and try to judge the length of time that passed between two tones. When they heard the tones in only one ear, they correctly judged the amount of time between them. When they heard the first tone in one ear, and the next tone in the other, they misjudged the length of time. For them, time got drawn out and they experienced it as longer than it actually was.
Just like with visual chronostasis, it's the shift in attention that stretched out time. Most people hear a rush in their ears as they yawn, so listening to that, then the music, then the rush again, then the music, might draw out the musical experience until the song sounds too slow.
Just out of curiosity, how many times did you yawn while reading this? It took me five yawns to get through writing it.