 According to this later text, players who place the mouthpiece higher on the lips, so that more upper lip is inside the mouthpiece, will direct the air downwards to varying degrees while playing.Performers who place the mouthpiece lower, so that more lower lip is inside the mouthpiece, will direct the air to varying degrees in an upward manner.In order for the performer to be successful, the air stream direction and mouthpiece placement need to be personalized based on individual anatomical differences.