voice box
The part of the throat where the sound of your voice is made; the larynx.
Mr. Smith's voice box was taken out in an operation, and he could not talk after that.
voiceprint
The graphic pattern derived from converting an individual's voice into a visible graph used by the police for identification purposes, much as fingerprints.
They have succeeded in identifying the murderer by using a voiceprint.
yeoman service
Help in time of need; serviceable and good assistance.
Sam was pressed into yeoman service in organizing our annual fundraiser for cerebral palsy victims.