The Elderly Novice Virtual Organist


This glossary describes organ-specific terms used on this website. It is not intended as a source of general information; for this see the relevant sections on this website.

Stop names are specifically excluded; for the most comprehensive reference available, see Encyclopedia of Organ Stops.

Accessory Stop

A control found with the Stop Controls that is not a speaking stop. Types of accessory stop are Coupler, Tremulant, and Toy Stop.


There are two types of action that determine which pipes will sound: the stop action, and the key action. These may be mechanical (in older organs, and increasingly in modern ones) or electric; other types of action used mainly historically include tubular-pneumatic and electro-pneumatic. Another type of action is the combination action triggered by pistons.

Barker Lever

A pneumatic lever used in some organs with mechanical key action to reduce key resistance. Introduced during the mid 19th century to deal with increasing wind pressures.


Use of the same rank in more than one division to reduce the number of pipes required. See Borrowed Stop.

Cantus Firmus

In early music, a term used for a melody used as the basis of polyphonic composition. On the organ, this would typically be played with the Choralbass.


The term given to the initial transient when a pipe starts to speak (perhaps something like a cough). In an organ with mechanical key action, it can be controlled by varying the force with which the key is hit.

Combination Action

Triggered by pistons that contain a combination of stops. This action changes the combination by physically moving the stop controls involved. This both enables stop controls and pistons to be used interchangeably, and gives the organist visual indication of the effect.


A means of combining two divisions of the organ by uniting keyboards. See Coupler.

Crescendo Pedal

Available on some organs to change the volume by successively adding or removing stops in a predetermined sequence.


A set of stops normally associated with a keyboard, but may also be a floating division. See Division.

Expression Pedal

A pedal (swell or crescendo) that allows the volume to be continuously adjusted while playing. See Expression Pedals.

Floating Division

Normally found only on large organs, this is a division that is not normally connected to a keyboard, but may be connected to the required keyboard when needed by means of a Coupler.


The most commonly used class of organ pipe, that produces sound without moving parts. See Flues.


A series of integer multiples of the fundamental frequency; the presence of these give musical instruments their specific timbre. See Harmonics.


This is the name of the main manual on a German organ, but also the name of virtual organ software; see the producer's website. The only other similar software is GrandOrgue.

Key Action

One of the two actions of the organ, operated by the keys on the manuals and pedals. See Stop and Key Actions.


This normally operates on a Division of the organ, and may be played either with the hands or with the feet. See Keyboards.


Another name for kneeboard.


Vertical panel behind and above the pedalboard. See Kneeboard.


An organ keyboard for the hands. See Manuals.


(Musical Instrument Digital Interface) a protocol developed in the late 1980s to transfer signals from devices such as keyboards and (in the case of the organ) expression pedals. Used extensively by virtual organ software as well as the more recent digial organs. See Connecting MIDI.


An organ stop comprising several ranks. See Mixture.

Mutation Stop

An organ stop comprising a single rank at non-octave pitch. See Mutation.


A flat (not raised) note on a keyboard (usually white on a manual). See Keyboards.


A keyboard for the feet. See Pedalboard.


A button under the keys of a manual typically used to activate a pre-recorded stop combination. See Thumb Pistons.


A type of organ that can be carried.


An organ that can be moved, and would normally have ranks no greater than 4'. Also used for a division of an organ that produces a similar sound.


Refers to intervals that correspond to the harmonic series - see Harmonics. For example, a pure perfect 5th has the frequency ratio 3/2.


A row of pipes producing the same type of sound. See Rank.


One of two commonly-used classes of organ pipe, that produces sound by means of a vibrating metal tongue. See Reeds.


The art (unique to organists) of creating an appropriate sound by combining the available stops. Also refers to the selected combination(s) of stops. See Stop.


An organ stop comprising two ranks that produces a difference product. See Resultant.

Sample Set

The set of recorded sound samples, and other data such as images and the organ definition used to implement a virtual organ. See Sample Sets.


A raised note on a keyboard (usually black on a manual). See Keyboards.

Speaking Stop

A control found with the Stop Controls that is involved with the stop action (i.e. in opening one or more ranks of pipes).


This may refer to either a speaking stop (see also Stop) or to an accessory stop.

Stop Action

One of the two actions of the organ, operated by the stop controls on the console. See Stop and Key Actions.

Swell Box

A chamber with shutters, used to enclose a division of the organ so that the volume may be changed using a swell pedal. See Enclosed Division.

Swell Pedal

A pedal that allows the volume of an enclosed division to be changed by opening and closing the shutters of the swell box.


The application of adjustments to pure intervals to make them align with the 12-note chromatic scale. See Temperament.

Toe Stud

(also Toe Piston) This has the same function as a piston, except it is operated by the feet.

Toy Stop

A type of accessory stop that produces sound effects not involving pipes (for example, percussion and bird song).

Tracker Action

Mechanical key action, in which key presses are transmitted by means of rods of wood, aluminum, or other material.


A wavering effect created by varying the wind supply. See Tremulant.

Undulating Stop

An organ stop comprising two ranks, one slightly detuned of the other. See Undulating.


The creation of stops of different pitches using the same rank. See Unified Stop.

Virtual Organ

This is an organ that generates sound by combining in real time recorded samples from one (or possibly multiple) real organs. See Why a Virtual Organ?.


The art of adjusting an organ pipe so that it produces the required quality and quantity of sound, and is consistent with other pipes in the rank. This is firstly done in the workshop, using a small organ known as a "voicing rack". Final voicing (known as "finishing") is done after installation, and may take several months for a large organ. Different types of adjustment are required for Flues and Reeds.


The pressurized air fed to the pipes. Wind pressure is normally measured in inches of water. It is typically around 3", but may be much higher (up to 100") for some reeds.

Wind Chest

The container of pressurized air on which the pipes stand.