Canvas has a feature which gives a warning when the student is running out of time (60 minutes left, 5 minutes left, 1 minute left). However, this warning is a small pop-up that is open for five seconds.
When I have students working on problems, they can easily miss this warning. It should be improved by doing at least one of the following (and preferably both):
Being larger, more visible, perhaps flashing
Playing a sound
Currently, there does not seem to be any way to do this, or have an audio file play when the quiz starts. (I've seen references to creating links which allow the students to play sounds, but this would be automatic.)