The long-rumored Sonos headphones may be close to release, as a German patent application reveals the latest over-the-ear design.

It has been several months since we last heard rumors of Sonos' first headphones. Another U.S. patent application filed last September revealed several design candidates and hints of features. The latest application, filed by the German Patent and Trademark Office, appears to show a more detailed and sophisticated design for Sonos headphones.

Notable design changes since the last application include a simpler headband yoke, slimmer and more rounded earcup enclosure, and added Sonos branding. The new design also has larger ear cup pads than the previous design, although exact dimensions are unknown.

The patent adds further interest to comments made by Sonos CEO Patrick Spence during a recent earnings call in which he revealed that the company is preparing to launch a new product "next month": March 2021.

With the recent discovery of new Sonos speakers, apparently related to Sonos Move, and the relative silence on Sonos headphones, it seemed likely that speakers would be the first to appear. Now, however, it is possible that these headphones will be released in March instead.

What is being questioned in this new filing is how accurate the September information about the headphones' specs and features will remain. That U.S. filing detailed very advanced headphones with two drivers in each ear, smart assistant functionality, active noise cancellation, and integration with Sonos' signature multi-room system.

These features may have changed as well, as the design has obviously changed; Sonos tends to target the high-end market, so don't expect its first headphones to be a low-end offering. More details about Sonos' plans will be revealed next month at the latest.