Selections from the installation The Prepaid Piano, recorded 21–24 February 2013 during the Unmenschliche Musik/Inhuman Music exhibition at Haus Der Kulturen Der Welt, Berlin. Inside a grand piano, five mobile telephones rest directly on the strings in five different areas of the piano soundboard. Calling any one of the telephones activates its vibration alarm, thereby directly ‘playing’ the strings on which the phone happens to be lying.
Audience members choose which parts of the piano are ‘played’ by calling any of the five telephones’ numbers — either from their own mobile phones or from the provided stationary telephones.
Contact microphones attached to the piano’s soundboard pick up the sounds of the mobile phones vibrating the piano strings and pass them on to a voltage-controlled modular synthesizer.
Incoming signals above a pre-determined amplitude threshold at the synthesizer’s input trigger its recording and modulation functions. The incoming audio is looped and modulated by the synthesizer and played back through stereo loudspeakers.
Subsequent calls to the phones produce new incoming signals that gradually displace the previously recorded audio. Additional layers of sounds are added by intermittently tapping and knocking on the piano, manipulating its strings directly, repositioning the mobile phones, etc.
Using the audio-to-MIDI function in Ableton Live software, the Prepaid Piano recordings from side A are algorithmically analysed and converted into MIDI notation. When applied to the harmonically and rhythmically ambiguous Prepaid Piano recordings, the audio- to-MIDI device’s inherent limitations are magnified. The MIDI notation it generates under these circumstances is effectively an original composition which (although distantly related to the source material) is the result of the audio-to-MIDI algorithm’s inability to correctly ‘read’ the information it is presented with. The newly generated MIDI notation is then used to control and play a synthesizer consisting of an oscillator, sampler, filter, and effects modules.