> "
OCR of short sentences from invoices or similar and fluid speech recognition of often grammatically incorrect sentences are problems of a very different magnitude. OCR is easy in comparison of actually spoken speech recognition -- especially if it is supposed to run in real time"
OCR isn't comparable to speech recognition. Period. The problem needs to be broken into two parts: 1) speech recognition, 2) translation. I was addressing those parts separately. However you're right that translating natural spoken language, which is full of grammatical errors and other nuances, would be a greater challenge than short passages of official documents.
> "and they simply suck for any language than english. its easier to talk to my devices in english than in german. and this is despite my poor pronunciations"
I'll have to take your word for it. But suffice to say there are several competing speech recognition engines, some better than others. So it might be that your devices use an engine that's poor at recognising German. Although equally you might be using one of the better engines. Hard to say from this high level overview. However the fact that they do work against your pronunciation of English is promising as it at least demonstrates how well these engines can cope with different accents - which is one of the hardest stumbling blocks in building speech recognition.
> "not at that size. the power cell would have to be tiny"
Indeed but we've already seen tiny power cells in watches and other modern gadgets. Given the earpiece only really needs a speaker, bluetooth receiver, some kind of DAC, and a battery; half the device could be the battery.
Just to be clear, I'm not suggesting this thing would have a great battery life though. But I still wouldn't be surprised if lasts a few hours - which is still comparable to some smart phones (sadly).
> "which would mean that they'd need bluetooth for permanent connectivity. this would drain the battery even more."
I did say it would need bluetooth. But realistically bluetooth doesn't suck that much power. The speaker would easily be a heavier power draw.
To summarise: there are obviously going to be difficulties - clear technical challenges - in build this kind of device. But I do think the technology is now at a stage were we can at least prototype something. And that was the crux of argument. The earpiece might not be a perfect gadget, but those gadgets who are first to market are seldom perfect.