Audio quality peculiarities on mobile YouTube app

I noticed a weird thing today, watching Harvard i-lab | Startup Secrets Part 1: Value Proposition – Michael Skok, and that weird thing was that the audio for this video sounded really bad when played through my iPhone 6S speaker but sounds totally fine when I plug my headphones in. There is definitely audible compression-related distortion even through the headphones but it’s not at all a problem for listening comprehension. In contrast, the audio is extremely difficult to understand when played through the iPhone speaker. I wonder if this is app shenanigans or if it is an interesting hardware (i.e. speaker + drive electronics) interaction with the raw audio signal from the YouTube stream. I am kind of hoping for a weird corner case where the speaker’s frequency response is emphasizing the distortion in the audio signal.

To be continued… hopefully…