The larynx is a mass of cartilage at the top of the trachea. It is commonly called the voicebox.
The larynx contains folds of muscle called the vocal folds (sometimes called vocal cords). These vocal folds are connected to the larynx by the arytenoid cartilage at the front, but the other ends are left free. The opening between the vocal folds is known as the glottis. These folds can be relaxed, letting air flow freely through the glottis, or tensed, so that the air vibrates as it passes through the glottis.
Sounds that are produced with relaxed vocal folds are known as voiceless sounds, and sounds that are produced with tensed vocal folds are known as voiced sounds. If the folds are only partially closed, a whispered sound is produced.
Voiceless
Voiced
Whisper