This really highlighted how much more difficult it is for me to understand people over the phone.
(thread)
And it wasn't just a side effect of lip reading — even when I looked away from the screen, I felt much less fatigued listening to the webcam callers.
In most cases, on phone calls, audio is sampled at 8 KHz.
(In some cases, you *may* get ≥16K if it's a mobile-to-mobile call, both phones and networks support HD Voice, and the providers agree on how to send it.)
That's significantly higher than the typical phone call. And the difference isn't trivial.
Note how the /s/ and /f/ are very distinguishable in the spectrogram—but almost entirely above 4 KHz.
So if we record the same audio at 8 KHz, that means those frequencies above 4 KHz disappear.
Note how /f/ and /s/ are *much* harder to tell apart now!
It's because a huge chunk of the frequency range you're used to is just…not there at all.