Why are some languages so much louder than others?

I think it's just that some languages are full of passion when spoken by those who understand that

I still have to tell my husband we're not arguing when me, mum and sis speak Greek

Not only some languages, but some dialects. You listen to a Spaniard speaking Spanish, and it sounds beautiful and romantic. You listen to two Mexican guys on a construction site speaking Spanish? Like Andy Kaufman in a conversation with himself.