Well, timbre is related with the envelope of the acoustic wave. The form of the wave will be received by your ear and then translated to electrical impulses to your brain. I think, that we are adapted to consider "continuous and smooth waveforms" as "nice", so timbre will be one of the first characteristics that your brain will analyze.
You could do research on how a typical 20 year old male would sound and you could try to mimic it. With practice you might be able to voice act it really well
Not serious <----- is the answer you are looking for
