How Do Pipe Organs Make Music?

It starts with air...

After being pressurized by an electric blower, and stabilized by a reservoir, air enters each windchest of the organ. Air from this windchest will flow into individual organ pipes when two conditions are met. The organist turns on a stop action with a draw knob or stop tablet on the console to allow a particular rank or set of pipes to be played. Then, any keys pressed on one of the keyboards will open note action valves allowing air to enter the pipes which sound the corresponding notes. Most pipe organs today use electricity to control the stop actions and note actions and are called electric action pipe organs.

Then the air vibrates, making sounds...

Each pipe in an organ is unique, having precise length, diameter, shape, material content, and numerous other details. The most common pipes, called flue pipes, have a toe, a foot, and a mouth that allow air in and out of the pipe. When the note action valve is opened at the toe of the pipe, a column of air is caused to vibrate in and around the body of the pipe. The characteristics of these vibrations depend on the many details of how the pipe is designed and determine what the pipe sounds like, including the special way that the sound starts (the attack) and stops (the decay). Other pipes called reed pipes feature a brass or phosphor-bronze reed that vibrates as air enters through the pipe's toe. The characteristics of the reed's vibration are influenced and supported by air vibrating in a reed resonator, a metal column similar to the body of a flue pipe.

In both flue and reed pipes, the column of air actually vibrates in many different ways simultaneously, and the often complex mix of these various harmonics or partials determine both the pitch and the rank's characteristic sound or tone color. Within a particular rank of pipes, each pipe has common features and proportions but every pipe is a different size. Any pipe sounds similar to the other pipes in its rank, with the shorter length pipes having a higher pitch. Each rank has its own tone color, and various ranks may be played in combination with others to create the desired effect.

The sounds are made to blend...

The sound from each pipe is designed and adjusted to blend with all the other pipes in the organ and to give the best possible results in a room. This custom design is done by highly skilled craftsmen known as pipe voicers. The size, shape and acoustic properties of the room, and the number of people the room is designed to hold, are taken into account.

Every pipe makes its own sound and is in a particular position different from every other pipe in the room. Because of these unique positions, each harmonic vibration from each pipe reflects differently from the church walls, pews, and so forth. As a chorus of notes are played, the sound reaching each person's ears is very rich and complex. Often described as "thrilling" and "uplifting", this sound is ideally suited to supporting congregational singing in much the same way that a full orchestra supports the presentation of a musical play. The blending of the sounds of many individual pipes into a complex chorus is a key reason for the superiority of pipe organs over electronic organs, which are inherently limited to relatively few loudspeakers from which the sound originates.

Pipe organs are unparalleled custom creations for making music!