We have all been on a plane and tried to plug our mobile headphones into the on-board movie system, and it did not work. The reason? Your headphones have an extra channel for a microphone, and the port on the plane is made for simple left-right stereo sound.

This kind of problem abounds in technology, but particularly so in audio, so we have put together a brief explanation to help you understand what to do in key situations.

Sizes of audio jacks:

Commonly referred to as an audio jack, technically a plug and socket, and the main sizes are: 6.5mm, 3.5mm and 2.5mm diameter.

Connect two pair of stereo headphones via a splitter to one source:

Standard splitters, such as this set, split a single 3.5mm headphone port (TRS 3-position) into two ports of the same type. TRS stands for “Tip”, “Ring” and “Sleeve” and is a 3-position standard stereo headphone jack with left and right audio. This may be useful if two people want to use two headphones to listen to the same audio device at the same time. Both left and right audio channels are provided to both of the “split” connections.


Tip – ensure both the source and the headphones are the same type, i.e. with or without the microphone.

Connect stereo headphones and a microphone to one source:

Although similar in appearance, adapters such as this splitter are very different from the simple splitter above. They convert a single audio port on the source device that includes a microphone (3.5mm TRS 4-position) into two distinct ports: one 3.5mm headphone jack and one 3.5mm microphone port. This is typically used to connect a headset with two TRS plugs to a computer or mobile device, see the image below for reference.



Connect a computer with separate headphone and microphone jacks to a single headset:

Adapters such as this one provide the opposite solution as the adapter above. They convert from a 3.5mm headphone jack and a 3.5mm microphone jack on the computer to a single 3.5mm TRRS 4-position audio port. This is typically used to connect a newer integrated headphone/microphone with a single TRRS 4-position plug to a computer or laptop with two distinct ports. Another “Ring” is added with the microphone channel, to make a TRRS-4 position plug.


There are two standards for the wiring of TRRS plugs, OMTP and CTIA. Most (i.e. Apple, HTC, Nokia, Sony, Microsoft, Android) have moved to CTIA, but some older devices from Nokia, Sony and Samsung still use the older OMTP standard, so check with the manufacturer of your device to determine which standard it works with.

Talk to StarTech.com:

If you want to find out more about our selection of splitters, or talk to one of our experts about your connectivity needs, please get in touch with our Tech Support Team.

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