A study of brass instrument ‘‘lipping’’ using an artificial mouth

Abstract

Sound is generated in a brass wind instrument as a result of aeroelastic coupling between the mechanical vibratory system formed by the lips and the acoustical vibratory system of the air column. The sounding frequency depends on the parameters of both vibratory systems, and is in general not exactly equal to one of the acoustical resonance frequencies of the air column. A skilled brass instrument player can vary the method of blowing to pull the note above or below an acoustic resonance; this technique is known as ‘‘lipping.’’ In order to obtain a clearer understanding of the lipping mechanism, an artificial mouth has been used to drive a trombone mouthpiece coupled to a cylindrical tube of variable length. The phase relationship between mouthpiece pressure and lip opening has been determined for near-threshold auto-oscillation over a range of air column lengths and embouchure adjustments, corresponding to lipping both above and below the acoustic resonance. Implications for the classification of the lip reed mechanism are discussed.