Hounds tend to "bay" rather than "bark". When a dog barks, you can say "he let out a loud bark". In a similar construction emphasizing the hound-ness of the creature, can you say "he emitted a loud bay that echoed through the chamber"? Or would it be a bark regardless?
According to dictionary.com, bay can be used as a noun:
So in that case, you could say "he let out a loud bay" but that would not be my first choice, as it sounds kind of awkward.
I would probably not use the intransitive form, and just go with a direct verb:
Possibly also consider howl as an alternative: