Subglottic Pressure
Quick Definition
The air pressure built up below the vocal folds that initiates and sustains phonation.
Factual Definition
Subglottic pressure is the air pressure in the trachea below the closed vocal folds, measured in centimeters of water (cmH2O), which when sufficient overcomes vocal fold resistance to initiate and sustain phonation.
Full Explanation
Subglottic pressure refers to the air pressure that builds up below the vocal folds during the closed phase of their vibration cycle. This pressure is essential for initiating and maintaining phonation—when it exceeds the resistance of the closed vocal folds, they blow apart, beginning the vibratory cycle.
The relationship between subglottic pressure and vocal fold resistance determines many aspects of vocal production. Too much pressure relative to fold closure can cause pressed, strained phonation. Too little pressure relative to fold closure can result in weak, unsupported tone or difficulty initiating sound.
Different singing styles and vocal effects require different balances of subglottic pressure. Learning to manage this pressure through breath coordination is fundamental to healthy voice production across all genres. The concept is closely related to what singers experientially describe as ‘support.’