Microphone does not pick up sound | Bose A20 Aviation Headset

Determine if any recent changes have been made to the headset or aircraft.

If any changes or modifications have been made to either the headset or the aircraft, look into whether or not those changes could have unexpectedly caused this issue.

Determine if sidetone is a feature of the connected intercom.

The level of your own voice heard through the headphones is known as sidetone. Sidetone is a common feature but is not found in all aircrafts or intercoms, especially portable intercoms. If sidetone cannot be heard, determine if sidetone is a feature of the connected intercom.

Determine if any non-Bose adapter cables are being used.

The connectors on Bose aviation headsets are built to military specification standards and meet TSO certifications. Microphone audio issues can occur with certain portable radio adapters due to the use of non-military spec microphone jacks. The contacts within the mic jack may not line up properly to make a solid connection to the mic plug. Tolerances across numerous adapter cables have a wide range of deviation.

Try a different adapter, rotating the mic plug or reposition its depth in the jack until a connection is made. If the issue persists, contact the manufacturer of the adapter or device being connected.

Check if your own voice can be heard clearly through the headset.

You should be able to hear sidetone (the sound of your own voice in the headset). If you cannot hear sidetone, the issue is not with the headset. Check the settings on the audio panel and/or intercom.

Check if the headset works while connected but powered off.

If the headset works without power, the connections are correct and the headset electronics are the issue.

Connect the headset to a different panel jack or, if possible, to another aircraft.

Non-TSO equipment, worn jacks/loose connections, or incorrectly wired jacks (i.e. reversed stereo or mic / ground wires) in the aircraft can cause issues. If available, try connecting the headset to another jack in the aircraft or to jacks in a separate aircraft. If the headset works fine when connected elsewhere, the panel jack or wiring to the jack is the issue.

Disconnect all other headsets connected to the aircraft.

Unplug any other headsets connected to the aircraft intercom. If the issue goes away, it is related to another headset. Reconnect the headsets one-by-one to determine which, then check the settings for that headset.

Determine if the microphone type on your headset matches the type required by the aircraft intercom.

Aircraft communication systems are typically designed for one type of microphone: dynamic or electret. If the wrong microphone type is connected to the intercom, the mircrophone will not work properly.

Check the audio panel settings.

On the audio panel, adjust the squelch setting to match the headset mic level. Open or close the squelch setting while speaking into the mic until the mic signal is clear and consistent. Some audio panels have an Auto-Squelch (VOX) feature which can still be manually adjusted using squelch controls.