The SoundScratcher is an instrument that graphically represents the waveform of a sample buffer. Any buffer stored in RAM can be manipulated by the instrument. The instrument receives input from hardware such as the mouse or a Wacom tablet and the basic idea is that the user can draw on top of the waveform representation and control the playback of the sound that way.

There are various interactive modes in which the user can play with the sound:
warp – a granular synthesis where the location in the sound file is played constantly using overlapping soundgrains. Here the vertical location of the cursor represents the pitch;
scratch – by moving the pen (or some other sensor input) the user can scratch the buffer forwards and backwards like a needle on a turntable. In the spirit of turntables, the speed of the gestural movement maps naturally to the pitch;
random grains – here grains are represented as dots on the canvas. The sound engine reads randomly though an array of the locations of those dots, creating a granular cloud. The density of the cloud, the envelope length and envelope type of each grain can be controlled from the interface;
linear grains – same functionality as in random grains, but here the sound engine reads linearly through the list of grains. However, there is a randomising button on the left of the interface where you can randomise the list if you so wish. These settings can be stored using the "save" button and retrieved from the "settings" drop down menu.
worm – the worm is a creature that moves over the space of the sound with variable numbers of grains in its spine. The speed of the worm and the grain duration can be controlled; Press "a" to add grains to the tail of the worm and "s" to remove grains (or number of dots).
graincircles – these are circles of variable size and amplitude (represented as alpha in colour) inside which the sound engine spawns grains according to the set speed. Again the envelope and duration of the grain can be controlled. Press the Z key to UNDO (if you create a circle that you didn't like).
grainsquares – as opposed to the graincircles the squares always play the grains from the left point of its location. This makes it easier to create interesting rhythms and periodic sound textures than in the random space of the circles. The speed of the grain repetition can be affected in both the graincircles and the grainsquares by pressing the 1, 2, 3, or 4 number keys, representing the respective time relationships (3 against 2 or 4 against 3, etc.) Press the Z key to UNDO (if you create a circle that you didn't like).

We recommend using the Wacom tablet here as the instrument is more expressive this way, i.e. pressure on the tablet is translated to amplitude control of the soundgrains/scratch.

The gestural movements of the user can be recorded, stored and played back by the instrument itself. (the record/play path button has 4states: "prepare recording", "record", "recording", and "play" - it has these states in order for the user to trigger the recording from the SPACE button on the keyboard). That way the user can draw patterns on the instrument and leave it to perform on its own. The user could then for example open up another instance of Soundscratcher to perform with.