I’ve been trying to solve this problem for my in-laws for a few weeks, and I’m making no progress.

They have a Sonos Beam connected to a TCL 735 (Google) TV via HDMI/eARC. My father-in-law has Oticon hearing aids, and there is an Optical cable running from the TV to an Oticon “Box”. The hearing aids connect to the Oticon Box via Bluetooth.

I cannot get sound to output to BOTH the Beam and the Oticon box (the hearing aids are connected) so that they can watch TV at the same time. I bought an “HDMI eARC (CEC) audio extractor" but that’s not working either - sound DOES come out through the hearing aids, but nothing through the Beam soundbar. At a guess, Sonos is fussy/strict over the kind of signal it receives and doesn’t “trust” it from the audio extractor.

The TV sound option is set to “ARC”. There is an Optical option too. 

Can anyone offer any advice on this topic? I realise the issue is equally a TCL and Oticon issue, but I can't believe that I am the only person who has tried to set this up. My in-laws spent $170 with an audio-visual guy who spent time looking into it but wasn't able to resolve it. The local Oticon seller was of no help either saying “I don’t know about things like that”!