Here are some findings,
On my Toshiba 56hm66, have the pace 551 hd with HDMI to HDMI TV hook up. Simple, no extra 5.1 system.
First - Visit channel 600 (videorton, MTL area). That channel has no sound assigned to it. You should hear that beep sound but in a continuous manner.
Second - If you unplug your HDMI cable from the STB, you'll hear that continuous beep once more.
Third - If the HDMI audio is set to Analogue and L/R RCA cables are used in the respective Colorstream Audio port, you will NOT hear the beep. Sound volume will be much lower.
So, with no HDMI incoming sound you'll get that beep.
This could mean that only Toshiba's have this "warning system".
To counter this, the "gap" needs to be filled. Imagine having the audio output from the Pace always "on". This could be a fix.
Or, Toshiba could resolve this by removing the feature.
What do you guys think ?