The owl species that is often associated with the vocalization that sounds like "Who's that guy with the tuba?" is the Barred Owl (Strix varia). Barred Owls have a distinct call that consists of a series of hoots. Their call is commonly described as sounding like "Who cooks for you? Who cooks for you all?" or, in some cases, "Who's that guy with the tuba?"
The unique vocalization of the Barred Owl has a rhythmic pattern with a rising and falling tone, giving it a musical quality. It is often heard during the evening and nighttime hours, especially in forested areas where the Barred Owl is found. Their calls are used for territorial communication and mate attraction.
It's important to note that individual owls may have variations in their vocalizations, and other owl species may also produce hooting sounds that could be reminiscent of a tuba or similar phrases. However, the "Who's that guy with the tuba?" phrase is commonly associated with the vocalizations of the Barred Owl.