treble

having or denoting a high range; "soprano voice"; "soprano sax"; "the boy still had a fine treble voice"; "the treble clef"

three times as great or many; "a claim for treble (or triple) damages"; "a threefold increase"

having three units or components or elements; "a ternary operation"; "a treble row of red beads"; "overcrowding made triple sessions necessary"; "triple time has three beats per measure"; "triplex windows"

having more than one decidedly dissimilar aspects or qualities; "a double (or dual) role for an actor"; "the office of a clergyman is twofold; public preaching and private influence"- R.W.Emerson; "every episode has its double and treble meaning"-Frederick Harrison

the pitch range of the highest female voice

sing treble

increase threefold; "Triple your income!"