A new pair of Sony wireless headphones has been spotted in an FCC filing that may reveal the first specs and charging case design for Sony's WF-1000XM4.

The filing, discovered by the Walkman Blog, does not name the WF-1000XM4, which is expected to be Sony's answer to the Apple AirPods 3 and AirPods Pro 2. However, given that it has already been leaked and is the only one of Sony's unreleased headphones to leak, it seems like a pretty safe bet that the filing actually covers the WF-1000XM4. And it suggests that a true wireless bad is nearing completion.

The design image of the charging case is simply drawn, and although only a top-down view is shown, it is consistent with the elongated cases of previous Sony earphones like the original WF-1000XM3 and WF-SP800N. The WF-1000XM3 is feature active noise cancellation (ANC), and the WF-1000XM4 is almost guaranteed to retain this key feature.

For the new upgrade, the earphones in this document use Bluetooth 5.2. Therefore, the WF-1000XM4 will gain many wireless performance advantages over the WF-1000XM3 as well as the current AirPods Pro model, which uses Bluetooth 5.0. For example, the WF-1000XM4 can play music with lower bandwidth and power consumption by using Bluetooth 5.2's low-energy (LE) audio capabilities.

Bluetooth 5.2 also introduces the Isochronous Channels feature, which makes it easier for a single pair of headphones to connect to multiple source devices simultaneously and switch seamlessly between them.

The WF-1000XM4 also appears to feature an upgraded MediaTek SoC, the MT2822S. Details of this chip have not yet been disclosed, but the Walkman Blog claims that it is a rebranded Airoha AB1568. If so, the WF-1000XM4 will support the same 192kHz/24-bit lossless audio as the WF-1000XM3, while also offering much improved power management.

The filing even includes hints about a potential release date, as the FCC's short-term non-disclosure agreement expires on September 27 of this year. Whatever these new headphones are, Sony will want to officially announce them before then, so it is quite possible that the WF-1000XM4 will be released before winter 2021.

That would put it in competition with the AirPods 3 and Google Pixel Buds A, which are rumored to be released in late 2021.