Is Chris Brown a alto or tenor voice?

Men do not have an alto voice since that would be referred to a countertenor (a man who uses predominantly falsetto, naturally tenors (or even some baritones)). Chris Brown would have a tenor voice since he predominantly sing comfortably around D4-A4 which is the typical comfort zone for tenors. He is definitely not a countertenor either where falsetto is applied. Falsetto would normally sound nasal and brighter than a typical tenor.