Upvote:2
There's some science that animals are louder in cities, actually, to compensate for the ambient noise, not the reverse.
Dogs can also understand each other regardless of where they're from, so it's not like 'Spanish barking' is particularly different.
Spain has the 6th highest number of dogs in the EU, and it being a smaller country than some of the others above it, might make them seem more frequent.
However, other than that it's most likely just subjective views of areas people went to in Spain, if they were perhaps, unused to the sound of dogs barking.