Citation Excel (C560XL)
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 10
Communication Breakdown; Situational Awareness; Troubleshooting; Workload; Distraction
ATC Issue All Types
Air Traffic Control Separated Traffic
Procedure; ATC Equipment / Nav Facility / Buildings; Human Factors
Aircraft X on frequency; Aircraft Y handing off to sector 39. I attempted to advise Aircraft X that Aircraft Y would soon be on frequency. No reply was received. I tried multiple times until Aircraft X finally answered; saying they had heard and responded multiple times. I had heard nothing; not even a static or a squelch break. Aircraft Y was a PUB landing aircraft. My concern is that if I had descended Aircraft Y; and both Aircraft Y and Aircraft X had responded; but I was only able to hear one of the aircraft; I would have no way to recognize the dangerous situation. This particular frequency issue of not being able to hear an aircraft happens multiple times a month across multiple frequencies in my area. I believe it may be tied to a specific site (TAD? LHX?) but am not sure. I believe it is just a matter of time before an aircraft reads back something incorrect/declares an emergency and is not heard/reads back correctly but is assumed to be NORDO so a different and competing clearance is issued (ie. both climbed into each other) happens.In this case I descended Aircraft Y and was aware that communication with Aircraft X was questionable; so I closely monitored Aircraft X's altitude. Aircraft X remained level and there was no loss or unexpected action.This issue with the frequencies is unsafe and needs to be fixed.
Denver Center Controller reported an issue with similar sounding call signs and a consistent frequency problem in the area.