All hoarseness — every increase in noise in the voice — can be described in exactly two ways: husky hoarseness from air leak, or rough hoarseness from asymmetric vibration. This chapter explores both.
In the first type, the vocal cords do not come together as they should, allowing air leak. We call this husky hoarseness. The second type is caused by asymmetric vibration. Because there are two vocal cords, when they are not symmetric in terms of mass, length, or tension, they tend to vibrate at two different pitches. A physician would call this sound diplophonia — diplo meaning double and phonia meaning voice, so two voices can be heard at once. Usually, since the cords are only slightly out of sync, the diplophonia will be inharmonious and at our typical, rather low speaking pitch, the perception will be of a rough or gravelly quality. We call this rough hoarseness.
Whisper
The extreme case of husky hoarseness — vocal cords held apart so that only turbulent white noise is produced.
Gaps
Five characteristic gap patterns — posterior, anterior, central, split, and timing — each creating husky hoarseness by leaking air.