The sphere, or “sprite”, made up of wandering triangles traverses the cave, changing the sound generated by several cylindrical “stalagmites” as it moves. Both the sprite’s positon and its appearance have meaningful mappings in the synthesis engine. The point lighting in the cave casts a vague blue-ishness on all objects, creating a cooler, softer environment.
The synthesis engine for this project was written using the Tonic Audio addon for openFrameworks. Each of the 16 possible stalagmites is associated with one synthesizer voice, containing a sawtooth oscillator of a particular pitch, an ADSR controlling amplitude, and a lowpass filter. These 16 voices are then mixed and sent through a compressor and reverb to help create the ambience of the cave.
As the sprite moves, its Euclidean distance from each stalagmite controls the lowpass filter cutoff frequency of that stalagmite’s synthesizer voice. The height of the sprite is used to control the rate of an LFO that affects all voices simultaneously. “Freezing” the sphere (seen in screenshot 2) brings the LFO depth to zero, abruptly stopping the apparent pulsing as the triangular faces of the sphere vanish. “Sharpening the sphere (screenshot 3) introduces a large increase in filter resonance. This has the effect of both attenuating the low end and boosting high pitched sheen created by the filter’s resonant peak. The result of these mappings is a set of constantly sounding chords with individual voices becoming clearer and brighter as the sprite approaches them. This constantly moving and changing soundscape is interesting whether the user is actively modifying the contents of the cave or passively listening.