Assistive Listening Devices (ALDs) - radio aids and proprietary remote microphone systems - optimising listening opportunities

Revised version: Contributions by members of the ALTWG (Stuart Whyte, Brian Copsey, James Mander) including Educational Audiologists from the professional associations; British Association of Educational Audiologists (BAEA) (Claire Bateson, Anne Bailey) and BATOD (Teresa Quail). | View as single page | Feedback/Impact

Frequencies and transmission

Sometimes there can be interference or a break in the transmission.

●      A clear line of sight between the transmitter and receiver(s) will give best results.
●      Hiding the transmitter behind books, tins etc will decrease coverage dramatically irrespective of frequency of transmission.  
●      Be aware when using the system outdoors, that obstructions and weather can get in the way of the signal from transmitter to receiver.
●      Within a room, blind spots will occur if a metal structure or other obstructions are between the transmitter and receiver.

Below are some frequently asked questions - and answers - about radio aids and transmission of signals.

1.The building has a mobile phone mast on top.   
a) will it cause a health hazard?    No, there is an umbrella protective effect see Ofcom results at:                             
b) will it interfere with the radio aid?  No

2. Will the assistive listening device present a health hazard?  No

3. Will the WiFi interfere with the device? Extremely unlikely but the radio aid system may cause the WiFi reception to reduce.  In which case move the WiFi.

4. Can I run radio aid systems in adjacent rooms/classrooms: YES, but discuss with your supplier as minor technical adjustments may be required.

5. Are all manufacturers’ systems compatible? Not in every case. Also, some accessories may not be compatible with all ALDs made by the same manufacturer: always check.

6. I have completed all the checks, but I still cannot hear through the system.  Check you are not shielded from the transmitter aerial location.

7. Does the signal drop as batteries decline?  No - the radio aid has a battery limiter which shuts off the system when the battery level drops below a certain point (normally there is a bleep to warn that the battery is fading).

8. Does the signal normally fade away at a distance, cause distortion of ‘voice’ or just drop off? A Digital transmission has a cliff edge drop off when it goes out of range.

9. Why do by batteries run down so quickly?  ALDs mainly use small single cell batteries with a limited capacity.  If the ALD is used only as a hearing aid, the batteries last a reasonable time, but the battery life is shortened when streaming music or phone conversations as these require extra power from the battery. Listening devices with receivers activated will also use the battery quicker