Baron Samedi said:voice that was once described by her friend, the poet Jean Cocteau, as like "being swept away on a wave of black velvet".
She also had the drink/morhpine/doomed love aspect
Cocteau was briefly the manager of world champion boxer Panama Al Brown.
I think her voice is idiosyncratic rather than "velvet". I've been to Piaf's grave but Brel, I think, is buried on Tahiti or somewhere equally exotic.