There's an interesting video on the fastest meaningful musical tempo or speed, which looks at the interonset interval. It turns out that between 100ms and 50ms seems to be that limit: 10 to 20 beats per second. Or, at the low end, 20 Hz.
Which is the point at which a series of beats becomes a tone.
If you extend this out to a full day, and consider each beat a bit, via GNU Units:
You have: 20 bit/s
You want: M bit /day
* 1.728
/ 0.5787037
Mind, that's individual beats, which isn't how we convey information, but it's an interesting data rate limitation. Language encodes at different levels, and arguably people might be able to operate at higher levels.
For spoken English, most of us can accommodate roughly 100 words/min. A typical college-educated adult can read 300 words/minute, and at the high end, perhaps double that. (The less literate are closer to the 100 words/min of spoken speech.)
If a word is considered as 8 bytes (7 characters and a space), then a sustained maximum-rate reading pace would allow for just shy 7 MB per day of information consumed.
Speaking? About 1.1 MB/day.
Both of those assume a full 24 hour day without break, interruption, or sleep.
We can absorb more information in the form of complex tonal or visual signals, but I'd argue that the retention of that information is highly limited.