A sound feature produced by the vibration of the larynx (vocal cords). Sounds are voiceless when vibration is absent. For example, If you have your students touch their larynx at the same time as saying /z/ or /v/, they will feel a vibration. On the other hand, if they say /s/ or /f/, no vibration will be felt. All English vowels are voiced, but some consonants are voiced while others are not.