My Authors
Read all threads
I've recently had to participate in some Zoom calls where some participants were using computer audio and other people were using the phone bridge.

This really highlighted how much more difficult it is for me to understand people over the phone.

(thread)
It took *much* more effort for me to understand what the phone callers were saying than the callers with webcams.

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.
The reason for that? Sampling rates!

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.)
Meanwhile, most online voice chat services support audio with a sampling rate of at least 22 KHz - depending on the service, it may even go as far as 48 KHz.

That's significantly higher than the typical phone call. And the difference isn't trivial.
(I was going to post some videos with spectrograms and audio, but Twitter just ate the clips, saying the format was invalid, without recovering the rest of what I'd typed to accompany them. 🤬 So I'll try this with screenshots instead...)
Update: I figured out a way to encode the A/V clips so that Twitter won't choke on them, so I'll be able to post the rest of this thread the way I originally intended after all!
Here's an audio clip of me saying "sail" and "fail", recorded at 44 KHz, and an accompanying spectrogram with the cursor moving across it as the audio plays.

Note how the /s/ and /f/ are very distinguishable in the spectrogram—but almost entirely above 4 KHz.
In audio encoding, the sampling rate is 2 times the highest frequency that an audio file can reproduce.

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!
So yeah, if you have a harder time understanding people over the phone? It's not just you!

It's because a huge chunk of the frequency range you're used to is just…not there at all.
Missing some Tweet in this thread? You can try to force a refresh.

Enjoying this thread?

Keep Current with codeman38

Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

Twitter may remove this content at anytime, convert it as a PDF, save and print for later use!

Try unrolling a thread yourself!

how to unroll video

1) Follow Thread Reader App on Twitter so you can easily mention us!

2) Go to a Twitter thread (series of Tweets by the same owner) and mention us with a keyword "unroll" @threadreaderapp unroll

You can practice here first or read more on our help page!

Follow Us on Twitter!

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just three indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3.00/month or $30.00/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!