when the vocal cords are drawn lightly together, the air passing through between them causes them to vibrate. In speaking, when the vocal cords vibrate, the sound produced is a voiced sound. You can produce a voiced sound in pronouncing the beginning consonant in word like 'zoo','did','ban'.If the vocal cords are relaxed and apart, the air passes between them without causing vibration. When the vocal cords do not vibrate, the sound produced is a voiceless sound;as
when you pronounce the final consonant in word like 'hiss',or 'rich'