In the news

On a bike, unless you want to go down the full Daglo Derek look and fit mirrors then you don't have this, the only way you know what is behind you is via your hearing or shoulder checking. I usually use my hearing to prompt the shoulder check.
#expectstl/dr

Can you also hear cyclist approaching from behind? if so, can you also tell whether they'll overtake or undertake you? were you able to tell how many cars is behind you while in noisy traffic? can you tell whether a car is about to turn left? etc.

It is highly advisable to not rely on your hearing as they don't give you as much information as looking back do.