(Pocket-lint) - It's been over a year since the first rumours appeared speculating that Sonos was working on expanding its speaker portfolio to headphones, but now a patent has appeared adding fuel to the fire.

The patent, which was filed in September 2019 - the same time the company announced Move, its first battery-operated portable speaker - was granted in August 2020 and it not only offers information on what we might be able to expect from the design, but also how the Sonos headphones could work.

Based on the patent, there are two potential designs, both of which are over ears. One appears to be more traditional, with an ear cup either side, while the other option has stems on the outside of the cups, reported to have microphones at the tips. Bear in mind, this is just a patent and neither design might see the light of day.

In terms of how the Sonos headphones would work though, the patent suggests they could use Wi-Fi and Bluetooth, like Move, and they could feature voice control - presumably both Google Assistant and Amazon Alexa like some of its speakers offer - as well as physical controls.

1/3USPTO / Sonos

It's thought there will be multiple wake words and there's also talk of Active Noise Cancellation (ANC) in the patent. Additionally, the patent talks about a button which the user could tap and hold to "swap" content playback between the headphones and different devices on the local network - so Sonos speakers for example. It's not yet clear exactly how this feature would work in terms of the headphones knowing which speaker or speakers to swap the playback to.  

There's also no indication when - or if - we will see Sonos headphones launch, or what they might be called when they do but the patent certainly suggests Sonos is still looking to expand its portfolio outside of speakers and that's very exciting.

Writing by Britta O'Boyle.