A coyote howling with a more upward approach would allow that sound to travel in more directions than say when one is threat barking or yapping in a particular direction,most of the time in your direction from either a sound you have made or by the visual of the coyote seeing something he doesn't like in that direction.The mean average of a "lone howl" as reported in Marc bekoffs book on coyotes is 1260 Hz, I'm not a music or sound man so what ever that number is worth. I know studies have shown with the aid of sound amplification, that coyotes could be heard responding for miles after a coyote/coyotes had done a lone howl or group howls and people spaced out on mile ranged specific areas, like a chain reaction.
As far as hearing, a coyotes has great hearing and can pin point sounds to within ft of where that sound is coming from and I have had them do that from within 100's of yards away, off a sound played once to over a half mile away from a sound played 2-3 times at 30 seconds of sound spaced a few minutes apart, too howls and pup in distress at 15 seconds of sound and come in from 1/2 mile or more away on a dead run to the location of that sound.
I don't try to get technical with sound as that isn't my strong suit and I have nothing to sell myself, I know what sounds work and when they work to my advantage and like to have a mix of sounds to choose from given the coyotes age,sex and time of year I'm calling. Surround sound is great to my human ears and having clear sounds gives a caller confidence, I don't think anyone can say it makes a noticeable differance when calling coyotes though, as many 1,000's where called in with mouth calls and far less than ideal sound source before the advent of digital recordings and remote control callers.
The advantages of these callers are many fold and have been discussed, but will mouth calls work you bet and I still use them mixed with the Big Country, and non of it was stereo and I know some that can voice howl better than any recorded sound and it has a lot of volume and works extremely well, but there is a limit to ones vocal cords and how many times you want to use them in that fashion in a given day.
Will stereo be an advantage in calling? I'm betting if it sounds good to the user then it will build confidance and that in itself will be of help, and who knows with sounds what may happen, I know when I run both of my speakers on the big country I have a lot of volume to me that is a big advanatge and what I want from a caller and that it is clear helps my confidance.
I feel in pressured areas and working adc it is as important of what sound comes out of the speaker/speakers as anything else as far as mono/stereo goes. If I have a choice sure I want a stereo machine because I can hear the differance in mono/stereo sounds, when switched on my radio, it sounds better to my ears in stereo, goes back to the confidance thing again.
Loud,clear and realistic are my major focus on the sounds I use, I don't get into khz and all the other issues that sound guy's want to split hairs with.As long as it all calls coyotes on a consistant basis and the coyotes react to it as a positive reaction and I kill those coyotes I'm a happy caller.
