The Significance of Embouchure
When it comes to playing any wind instrument, the embouchure becomes the single most important technical detail. Poor embouchure means poor intonation, poor tone, and limited facility in general. Embouchure refers to:
The position of the lips on the mouthpiece (brass)
The position of the mouth around the mouthpiece (single reed instruments)
The position of the mouth around a folded, exposed reed (double reed instruments)
The position of the lower lip against an embouchure hole (flute and piccolo)
As a composer, why should I worry about embouchure?You do not have to specifically concern yourself with embouchure. However, it's so fundamental to playing wind instruments that you should be aware of the role it plays in sound production. Good composers are knowledgeable about the instruments they write for. Further, you will develop deeper relationships with musicians if you understand the technical demands they face.
For brass, lip coverage on the mouthpiece is a critical factor. On single reed instruments, proper synchronization of the teeth, lips, and oral cavity itself become principal concerns. On the flute, the direction of the airflow is paramount, and on double reeds, a tight seal around the reed is required to even utter a sound.
Embouchure varies greatly from instrument family to instrument family. Many subtle factors influence the development and maintenance of embouchure. In addition to the aforementioned, facial muscles, the jaw, and the instrumentalist's posture affect the sound quality that is produced.