After a stop leaves the pipe maker, they go to the voicing room (usually in the same factory). Voicing consists of adjustment of the pipes in order to produce the desired sound. In the voicing room, the stop is placed on a voicing machine – a kind of ‘one-manual organ’, basically a windchest with a keyboard and wind supply.
Voicing of flue pipes largely consists of adjustments to the mouth, the lower and upper lip, the languid and the toe-hole.
Voicing of reed pipes includes the actual manufacture and curving of the reed tongue. Curve shape, tongue material and thickness are part of the voicer’s responsibility.
In both cases, tradition and experience play a large role and are passed down through generations of craftsmen, sometimes father and son.
Voicing is, needless to say, critical to the sound of the final instrument and there is a subtle interaction between the actual pipe design (as executed in the pipe shop), the voicing and the tonal ensemble which the finished instrument produces once installed. On important instruments, the voicer may do much subsequent regulation once the instrument is installed.