None of the paps howl.... except Bernard. He doesn't yap like the others and instead goes 'Wooo wooo wooooooooooo' like a tiny hound dog. Harry did that too (Nard's uncle) and Nard's mom and littermate did too but none of the other papillons did. Always odd to me but the four of them are 1/2-3/4ths Japanese lines so maybe those lines just bay like that? The breeder was always slightly perplexed at how different their vocalizations are too.
The other paps have shown no indication of howling, just screeching, chirping, and yapping.
The shelties on the other hand were all major howlers. They'd all howl with you if you started up and Nikki loved howling with things like... certain songs, certain words, sirens, the blender, my clarinet, the piano, etc. I miss being able to lead a howling chorus with the dogs.