What a great idea. Seriously. Using a medium like a colored pipe cleaner to give instant feedback to a speaker could do wonders in situations where the audience is culturally programmed not to say anything even though they're not getting anything out of the presentation -- just to be polite.

When I'm talking, I try to see hints about how I'm doing and how should I perhaps correct my direction. I want to see those hints.

The problem is that people tend to subconsciously tone down their visual cues and explicitly decide not to say something out of politeness. Using a silly tool like a pipe cleaner could indeed help -- handing out those pipe cleaners would be a clear sign that feedback is wanted and people wouldn't need to worry about formulating the feedback into a polite enough sentence.

Similar facilities are being used in some webcast products, for example, where the audience can switch themselves to red/yellow/green state to let the speaker know that he's going too slow/fast.