Other than conflict or lust, cats do not vocalize, among themselves. They communicate via body language. They have learned, however, that WE communicate verbally and have adapted to that.
One of my past cats used to sit on top of the refrigerator and "sing". Sinatra he wasn't but, it was an endearing habit.
Of my thre cats, Rowdy has the largest vocal range. She has a "m-r-r-row", "p-r-r-rp" and numerous chirps and trills. When she gets herself shut into a closet or bedroom, she yowls and when she wants me to let the dogs in, she paws at the back door and says "mewp".