Things like doorbells and baby monitors understandably often need to be modified to produce a visual or tactile signal that is perceptible to Deaf people. There are also concerns about how to alert Deaf people in the case of an emergency like a fire or tornado as these are usually signaled via a fire alarm or tornado siren. Do some brief internet research on emergency notification methods for those in the Deaf or Hard of Hearing community and describe two methods that are currently available.