Paul,No doubt elk numbers have been reduced by the injection of wolves but I don't see any real difference in their volume of vocalization. Again, bulls bugle according to the situation they are in, some require more volume than others. For instance, when a bull is talking too his cows in a conversational manner he does not use the same intensity or abrasive bugle as he would when faced with a bull trying to steal a cow or calling his cow/cows from him.
Yes, elk still talk in their loud voices regardless of wolves in a unit or not! When hot cows are present it would take an act of God to totally shut them up, wolves or hunters can only accomplish this very short term. The opposite is also true, no hot cows regardless of area hunted & you will find bulls are much quieter, hot cows present arouses a bulls Instinct to Breed & bugling can become competitive among multiple bulls present! I'm referring to OTC or Draw units, it doesn't matter.
I'm referring to hunting elk over 40 years in the same areas prior to the wolf introduction & to present day. I've also hunted other states with & without wolves & see little difference in vocalization. The biggest factor is lots of bulls & you have potentially more bugling, fewer bulls & you can experience less bugling. Fortunately we do not need bulls bugling repeatedly in order to call them in.
ElkNut/Paul