What is DM?

DM stands for Digital Modulation and is a generic name for modulation techniques that uses discrete signals to modulate a carrier wave. In comparison, FM and AM are analog techniques.The three main types of digital modulation are Frequency Shift Keying (FSK), Phase Shift Keying (PSK) and Amplitude Shift Keying (ASK).


DM eliminates transmission noise and offers improved robustness to signal interference. However, it is not uncommon for DM to introduce time delay due to the processing required. Comfort Audio’s SecureStream Technology (SST) is especially designed to avoid this.


My receiver just makes a noise! What kind of a fault is it?

Noise from your receiver mostly tends to be due to two factors. Either you have interference on the channel you are using, or the units are not paired properly (see pairing below.) Try using a different channel or carry out pairing again.

My battery does not last as long as I would like it to. Is there anything I can do about that?

The best way of ensuring as long a life as possible from a Li-ion battery is to use it. Avoid leaving the battery in a discharged or fully charged state for long periods. If a product is not going to be used for a longer period of time, the battery should first be charged to around half (40%) capacity and then charged just a little at regular intervals to prevent so-called deep discharge, which can harm a battery. Batteries of lithium ion type do not have the so-called memory effect and do not have to be completely discharged as do NiCd batteries, for instance.

How do I pair my units?

Pairing of units can be done at any time using the pairing button or via the unit’s menu. For more information on pairing, please read our fact sheet for pairing units


What frequencies am I allowed to use?

In most European countries, channels 1-3 (863.250-864.750 MHz) may be used for hearing products. However, you should always check with the frequency assignment authority in your own country which channels are free and which require a license.

I can hear myself speaking too loudly when talking over the phone using the TeleLink. Is there anything I can do?

This is often due to the volume on the telephone being too high. Try reducing the volume on the phone and increasing the volume on your DC20 instead, under Connections – TeleLink – Tele in level.

I’d like to be able to listen to two people delivering a presentation with my DC20 – how do I do that?

As the Conference Microphone DC20 only has the option of receiving sound from one additional microphone, it needs supplementing with another unit with a mixing functionality, such as a Microphone DM20. Transmission can then be performed in a chain consisting of DM05, DC20 and DM20. 

How do I use my equipment to listen to TV?

Comfort Digisystem and Comfort Contego come with an
audio cable that allows you to connect your hearing product
directly to a TV, radio, computer or other sound source.

See the guide Connection to TV.pdf.