Thanks to Bob for this question.
Silence always works if you have the mental and physical presence to back it up.
However, in my declining years I choose not to antagonize those who do not require it. I will be courteous to down and out types rater than walking over them or looking through them. I now reserve silence for grifters, set-up men, muggers sizing me up for a hit or drug dealers. A lot depends on your personality.
A polite decline must be spoken while taking action, executing some coming and going act, and said with confidence, not as a note of apology.
link › jameslafond.blogspot.com
Of Lions and Men
Thanks, much appreciated. I'm assuming that the potential assailant wants to size you up by hearing you. A nervous, tremulous voice might be enough to convince the aggressor that you're easy an easy target.