Sonos is building a next-generation wireless home surround sound system

Sonos is hard at work on its next wireless speaker, according to a leaked filing with the Federal Communications Commission (FCC). The official certification from the US government agency signals that this new device – referred to only as "S18" in the official documentation – is currently being tested by the company.

According to Variety, the as-yet unannounced device is referred to as a "wireless smart speaker" in the FCC filing. The smart speaker is being paired with the existing Sonos Playbar during the initial tests, the publication reveals.

• Sonos Beam review
• Sonos PLAYBAR review

If the latest leak is accurate, this unnamed Sonos speaker is being thought of as an addition to an existing wireless home cinema set-up as much as a standalone device. 

Given that it's referred to as a "smart" speaker, we can expect to see Amazon's omnipresent smart assistant Alexa make an appearance. With the Sonos Beam, the voice-controlled assistant can be used to request songs, change the volume, read out the latest headlines and weather reports, control compatible smart home devices, and tell you what is currently playing on the speaker – even if the track is being beamed from your iPhone via AirPlay.

Unfortunately, FCC filings reveal little about upcoming products, so that's about all we know about the next Sonos product at the moment.

However, the smart money would be on these forthcoming device featuring Wi-Fi and Bluetooth connections, as well as backwards compatibility with the existing multi-room speaker line-up from the company, including the Sonos One.

Sonos already offers wireless surround sound in 5.1 configurations when users combine the Sonos One, Play:1, Play:3 and Play:5 speakers with the Sonos Sub. So, it's a little unclear what the so-called S18 could bring to the table?

Unless Sonos is looking to embrace 7.1 mixes, or Dolby Atmos support. Now, that would make the S18 a very interesting proposition to existing Sonos customers.

Only time will tell what S18 can bring to your existing Sonos smart speaker rig. Stay tuned, as T3 will have all the latest news as it breaks. And in the meantime, why not check our definitive list of the best multi-room speakers.