Upper lip (organ pipe)
The upper edge of the cut-up opening of an organ or flue pipe (counterpart to the lower lip).
What it means
The upper lip is the upper edge of the mouth opening of a flue pipe, that is, an organ pipe whose tone arises at an edge, as in a flute. It is the counterpart to the lower lip, the lower edge of the mouth. The air stream leaves through the slit between the core and the lower lip and strikes the sharply cut edge of the upper lip; there it is split and sets the air column in the tube vibrating.
Musical use
The shape and height of the upper lip, together with the width of the cut-up, determine the speech and tone of the pipe. Organ builders file and adjust it during voicing so that the pipe speaks clearly and with the desired character. A higher cut-up makes the sound rather soft, a lower one sharper.
The upper lip should be distinguished from the lip as a whole, which means the entire mouth area of the pipe, and from the reed of a reed pipe, which, unlike the upper lip, vibrates itself.
Performance practice
As an organist you do not see the upper lip but you hear its effect: a cleanly made lip ensures clear speech. The voicer adjusts it to the room so that the sound suits it.