The latest version of the HDMI interface is
2.1, and it offers numerous important changes. Relevant to us here is eARC, or enhanced Audio Return Channel.
While Dolby Atmos can be passed over regular ARC today (via
Dolby Digital Plus) eARC offers improved bandwidth for higher-quality Dolby TrueHD and DTS-HD Master Audio streams, including Atmos.
The new format also has lip-sync compensation built-in. This feature was optional in ARC, but is now required. This lets you more easily line up the sound with the visuals, something that has always been an issue in the modern TV era.
We'll start seeing gear with eARC this year. To take advantage of the new features, both pieces of gear must be eARC compatible. It is backward-compatible with ARC, but not with the new features. Fortunately, eARC should be available in far more gear than just high-end
8K TVs. Even though most TVs don't need the other features of HDMI 2.1, manufacturers will be allowed to implement just the portions of HDMI 2.1 most useful in that TV, i.e. eARC.
You probably don't need new HDMI cables for eARC. Older cables with Ethernet, either Standard or High Speed, will work. The new Ultra High Speed cables will work as well, of course. Chances are your current cables have Ethernet and you didn't even know, so they'll probably work.