So in your dojo your sensei (you?) actively encourage everyone to talk all the time about anything? Interesting. I've found that when someone is talking they tend to loose focus on their other senses, and don't feel uke/nage as much. One reason car phones are such a problem. When folks talk about a technique they stop feeling it, and use it as a reason not to watch more closely when it was demonstrated.
The point about the suicide attempt is an interesting one, as the point of that is not to keep a constant stream of noise going, and in fact it is important in counseling to be comfortable with silence, but to establish a dialogue with the patient, often through that comfort with silence. Novices are often unable to stand the quiet and keep jumping in at the wrong time because they feel the need for talking to go on.
The police tactics classes I've been to emphasize talking, but that is not to establish harmony, but dominance: the joint locks demo'd were painful and the directions were repeated in a loud clear voice to make clear to the 'perp' what he had to do to get the pain to stop (ie, get down, lie down, stay down, etc) really not about what was going on with the person, but since the lock was not effectively directing uke where he needed to go, words had to be used.