Deaf Tenant and Smoke Alarms

I have two profoundly deaf tenants in different properties.  

One is very proactive and has installed smoke alarms with a strobe light to warn him; the other is a vibrating pad that sits under his pillow when asleep.

The other tenant has confirmed he has not installed additional equipment to alert him.

The property has numerously hard-wired battery backup smoke/heat alarms.

Do I have a further responsibility to place extra measures in his flat due to his disability?  

I am thinking of the risk assessment section that mentions vulnerable people.  Or is this the tenant’s responsibility?

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