Advice on testing fire alarms in HMOs

HMO Licensing

As required, we test our fire alarms monthly which is the schedule recommended for the several  small HMOs we manage. However, there seems to be variation between different councils on how you manage 'in room' alarm testing. Some say to tell the tenant to test others that the responsible person must undertake or arrange for all alarms to be tested.  So does this mean asking for entry once a month? At the moment, we just stick ears to doors but hand on heart, I'm not sure that is very accurate. Asking for access every month is really intrusive though and we risk turning homes into  hotel rooms. How do other people do these tests? What is the NRLA view?