Asymmetries between the vocal cords — whether in tension, mass, length, or stiffness — tend to cause diplophonia. Both types of hoarseness, husky and rough, often occur together in the same patient.
Asymmetries between the vocal cords, whether in tension, in mass, in length or in stiffness, will tend to cause the vocal cords to go out of sync with each other during vibration. When out of sync, we have two sound sources and we will hear two pitches simultaneously — a double sound or diplophonia. We perceive diplophonia as a rough quality to the voice.
What You Learned
- Voice and hoarseness are physics in action — every change in the voice corresponds to a physical change in vibration.
- Husky hoarseness = air leaking between unclosed cords — white noise added to or replacing the pure tone.
- Rough hoarseness = two different sound sources — cords asymmetric in mass, length, tension, or stiffness vibrating at different pitches (diplophonia).
- Disorders frequently combine both types — a gap and an asymmetry often coexist; hoarseness is a general term that includes both huskiness and roughness.
- On endoscopy: mind two things — a persistent gap explains huskiness; departure from mirror-image vibration explains roughness.