Can't say that I've ever used or heard the yellowhammer sound. I've always used either jackrabbit or cottontail in distress with good results on both cats and coyotes. In my area, I start off with medium volume and increase to very loud. I'll back off volume when I field a response. Personally, the raspier and louder a call .... the better I like it. I figure the louder the call, the more area I can cover ... the more area I can cover, the greater my chances of a response. Also, this area is normally breezy to windy ... calm days are sometimes an exception. Make it sound as distressful as possible and make it loud ... works for me anyway.
Doug B