Acoustic Localisation for Spatial Reproduction of Moving Sound Source: Application Scenarios & Proof of Concept (NIME'16)

This page forms the appendix to the NIME conference paper of the same name. For details on the current implementation of alps, please see here

appendix A: audio files

The following two stereo .wav files demonstrate the spatialisation of a trajectory recorded using acoustic localisation techniques as an appendix to the article submitted to NIME 2016 titled "Acoustic Localisation for Spatial Reproduction of Moving Sound Source: Application Scenarios & Proof of Concept"

The first file is the original moving sound-source, me, playing the bass - line of Charles Mingus Haitian Fight Song on a viola, while walking along a circle of 8 loudspeakers, recorded on a Zoom H4 in stereo

The second file is a room recording using the same Zoom in the same position of the same sound - source which I recorded close-miked while walking the original trajectory. But this time I was not moving at all: As I measured the time delays between the microphone and the loudspeakers throughout the original trajectory, I was able to play back the close-miked recording on the 8 loudspeakers, panning the playback by using the distance estimates as an indication which loudspeaker was the closest.

appendix B: programme notes, leluhelikvartetti, (toy helicopter quartet)

Leluhelikvartetti is an homage to Karlheinz Stockhausen's concept of the Helikopter-Streichquartett, wherein the players of a string quartet are placed in a helicopter each, together with a pilot and a broadcasting engineer equipped with a camera. The sound and images of the quartet is are broadcast to a nearby concert venue, where the audience can hear the instruments' sound mix with the sound of the helicopters outside and watch the musicians perform on giant screens.

Leluhelikvartetti uses, due to the Finnish Governments funding cuts, toy helicopters. As the toy helicopters don't accommodate much personnel, some trickery is needed, whereby the individual instruments' sound will seemingly, as per magic*, come from the helicopters flying around the performance space.

The Free Improvisation String Quartet, (Yli-Tepsa: violin, Schlienger: viola, Castrillon: cello; Pyhälä: bass), in a further protest against any rules and regulations, will not adhere to any form of score, but will happily take cues and inspiration from the flight of the toy 'copters, in a audio-kinaesthetic conversation with the pilots.

*The magic:
The performance space shall be a circular area of approx. 12 m diameter, wherein 4 toy quadcopters of type WLToys V262 are flown by 4 pilots, moving around freely. The audience surrounds this area. The players of FISQ are set-up somewhere at some distance from the performance area. Their instruments are close-miked, so that each instrument is available as one mono channel to the sound system at the centre of the performance space

In the centre of the performance space stand 8 near coincident radially outwards facing loudspeakers of type Genelec 1029 or similar. The loudspeakers send an acoustic measurement signal just above the frequency range audible to the human ear. (18 - 30 kHz). The four toy helicopters are equipped with wireless microphones: Using time difference of arrival measurements by correlating the original signal on the loudspeakers with the measured signal on the helicopters, the positions in relation to the loudspeakers can be estimated. The positions are then used to apply amplitude panning to the signal from the quartet's instruments, thus spatialising the quartet's sound as if each instrument was playing from one of the helicopters. (That is, for an audience surrounding the performance space.) Further, the musicians of FISQ are also equipped with wireless audio senders, allowing them to move around freely during the performance.

The multiple layers of audio (Direct sound from the quartet; amplified sound through the loudspeaker array; the sound of the the helicopters) and the layers of movement (the helicopters trajectories; the musicians trajectories through the audience) create a densely woven spatial narrative.

Leluhelikvartetti was first performed as part of MuTe Fest'15 at Music Centre Helsinki, on 20th November 2015.
Its performance at Kling Gut! Symposium of Sound in Hamburg 2016 was awarded for "Excellence in Art, Design and Production of Sound" by the Audio Engineering Society Student-Section Hamburg.

appendix C: the matlab - playrec script

These matlab scripts are using playrec and the matlab/gnu octave vbap-library. These scripts are first steps towards an implementation. Not more.
This one needs to run first, but you'll need this auxiliary function and finally this one plays the trajectory back, with a wav file of your choosing.

the recording of the trajectory: Video

Sound from the camera microphone. With other words This is for documentation, not enjoyment! : )

NIME2016video - Broadband from Dom Schlienger on Vimeo.