This further implies that the change of voice at different times on different topics is very vital and significant.

So, with a quiet sigh for me, Biddy rose from the bank, and said, with a fresh and pleasant change of voice, 'Shall we walk a little further, or go home?

A mere reminder of Mom's touch or the sound of her voice on the phone is enough to change people's minds and moods, affecting their decision making in measurable ways.