What type of alarm clock does a deaf person use?
An alarm clock with a strobe light wakes up many deaf people, but those who are heavy sleepers may sleep through the light. Bed vibrators that include attachments placed under the pillow or mattress help wake up many deaf people Gallaudet University explains. Smartphones under a pillow also serve as alarm clocks. Smartphone vibrations can also serve as timers and as general alerts. Flashing lights can also alert deaf people to the doorbell and other sounds.
Sources: gallaudet.edu, pbs.org