Voiced or voiceless?

The third feature used in the classification of consonants, after the manner and place of articulation, refers to the activity of the vocal cords. Vocal cords are sets of tiny cartilages and muscles on both sides of the larynx. The space between them is called the glottis. If the vocal folds are brought together and the flow of air repeatedly forces them apart, a periodic vibration is produced and we speak of voiced sounds, for instance zzzzz, the first sound of English zebra or zoo.

If the vocal folds are separated, air can flow through the glottis without producing vibration, and the result will be a voiceless sound like ssss, the first sound in the Spanish word sapo. The contrastive use of the feature voice in Spanish occurs in the stop series only; par (pair) – bar (bar), tía (aunt) – día (day), corro (I run) –gorro (cap). In English, this is more systematic and also occurs in the fricative series and affricates, e.g. fan vs. van.