The Sony WH-1000XM4? I'm still on the Bose QC 35, but you got me curious. Could you explain how using it as a hearing aid works? I searched the web but couldn't find good references.
There is a noise canceling mode that let's you hear what is received by the microphone array and an option to "filter in voices while suppressing noise" (they call that voice passthrough). That section of the app is called "Ambient Sound Control" if that helps your research.
