Sony's WH-1000XM4 headphones have made an early appearance on the website of major US retailer Walmart, revealing key features beyond appearance.

The list, which TheWalkmanBlog discovered via a reader tip, details the features that Sony's upcoming wireless noise-canceling headphones will include. It also reveals a list price of $348, which is roughly the same price as the current Sony WH-1000XM3 headphones.

Included in the list of features is the long-awaited multipoint functionality, which allows the headphones to be paired with two Bluetooth devices simultaneously and switch which one is active at the push of a button. The listing also states that the XM4s can switch to a phone when a call comes in.

The Walmart listing states that the XM4s use DSEE Extreme processing to improve the quality of compressed music and audio files for clearer, more dynamic sound. This appears to be an upgrade of the DSEE HX processing used effectively by the XM3 headphones.

The XM4s will also add GPS to Sony's adaptive sound control noise cancellation feature. The marketing describes this as a way for the headphones to recognize frequently visited locations and adjust active noise cancellation accordingly. This is done in addition to existing systems that detect whether you are sitting still, walking, or riding public transportation and change settings for the best combination of cancellation and external noise filtering.

Also returning from the XM3s are touch screen controls that allow you to change the volume of tracks and play/pause with a system of swipes and taps. The LDAC audio standard, which improves sound quality, is also included. Excellent battery life is also listed, with a total playback time of 30 hours, and the device is advertised to run for 5 hours on a charge of only 10 minutes.

In addition, as XDA Developers discovered in a teardown of the Sony Headphones Connect companion app, the XM4s may also include a "Smart Talking" feature that automatically plays outside sound from the headphones when they detect you are trying to speak. It may also have a feature; we'll have to wait and see if this actually works, as there is no mention of such a feature in Walmart's listing.

Retailers seem to already know all about the Sony WH-1000XM4 headphones, so we expect Sony to announce them soon. If we had to pick an exact month, it would be August, exactly two years after the XM3 was announced.