This is a male coyote responding to the sounds of a siren. Doesn’t look like he’s too into it! The siren petered out quickly, and so did any enthusiasm for howling!
Male vocalizations appear to be lower pitched than females, and consist of more actual barks than howls. I’ve never heard a male sustain a tremolo the way a female does — I wonder if this is a generalizable truth, or if it is just so for the coyotes I’ve heard?