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The Persistence of Sound

Reverberation, in psychoacoustics and acoustics, is a persistence of sound after the sound is produced. A reverberation, or reverb, is created when a sound or signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space – which could include furniture, people, and air. This is most noticeable when the sound source stops but the reflections continue, decreasing in amplitude, until they reach zero amplitude. (Definition of reverb in Wikipedia/Valente/Lloyd)

The Persistence of Sound refers to a poetic interpretation of the physics of reverberation:  the space itself, responding ghostlike, to the signal. The invisible, audio-tactile, experience of space.  How finely we ‘listen’ as a society and as a culture, is one of the most fundamental ways of expanding our awareness and consciousness. The Persistence of Sound aims to augment spatial listening in such a concrete way that the listener is transmitted/ displaced (in sound) in many actual places in fractions of milliseconds via a sonically inter connected, resonant, physical acoustic loop.


The project will consist of a listening post where festival goers can listen and interact with an ‘audio tunnel’ which consists of a loop of selected spaces in Berlin (or 'nodes'). These nodes are sonically connected  via quality, low latency, internet audio (enabled by Rasberry pi audio network units, a Webtrc hub for controlling audio flow, and Ableton Live.  (See technical description for more).

Each individual space, acts as a node in the loop and is able to receive and send audio to the network.  Received audio is played out into a room, the reverberations and other ambient sounds of the space is in turn recorded and send back over the internet to the hub. 


Individual 'node' (room) example

From the hub the audio is routed to the next space, played over a loudspeaker, recorded and sent back to the hub. This process continues until the last space is routed back into the first space.  All happen simultaneously - a continuous flow of audio through all the spaces as a recombinant acoustic space.  


Daisy-chain, circular flow of audio from room to room, with the last space looping back into the first space.

Room acoustics of each space is accumulated and when the circle is closed, resonant frequencies from various places in the tunnel start feeding back into itself with a unique spectral character.  It is also interactive: festivalgoers can project any sound or vocal into the audio tunnel and hear it echo and reverberate in the remote sites, as it bounces from space to space. 

In the main listening post is installed one loudspeaker for each room or 'node' in the tunnel to get a rich and beautiful spatial sound field.

Listen to the first attempt (with DIY microphones and Musician Link (audio internet units). What you hear is an aeroplane flying over the town of Palo Alto, getting picked up by the audio tunnel, as well as the ambient sounds from all the spaces bouncing through the loop. Note, there are no effects added, the effects are purely the sound of the combined spaces.

Aeroplane flies over 7 connected spaces in Palo Alto - Cobi van Tonder
00:00 / 00:00

Context and larger scale concept:


There is a saying, that if one stands in one place and stares for long enough at the horizon, one can eventually see the back of one’s own head (seeing all around the globe)… Taking this analogy and substituting it with sound: what would you hear, if you listened for long enough from one listening post: could you eventually hear your own breathing from behind you?  If the earth was quiet enough, if enough reverberations could carry the sound, could you hear yourself later in time? 


With technology, could we progress a little closer to such a goal?  Imagine a listening post, with a single microphone and loudspeaker.  Now imagine a series of spaces (each with a loudspeaker and microphone), each with internet and network audio technology - something like Skype but better quality) plotted in a perfect circle around the planet.  The listener utters a sound, together with the ambience and acoustic reflections of the listening post all these sounds travel to the second space, the third, the fourth.... all round the earth, in an instant the sound emerges back into the listening post.  Your  voice just traveled in a perfect ring around the earth. What is now heard? Ok, let’s take a step back, instead of travelling around the globe with this audio experiment, we start with Berlin. 

Long term vision:

With your support, the artist hopes this could be the start of a journey that leads to finally create an 'acoustic ring around the earth' to promote awareness of the importance of sonic ecologies and the act of listening.  You will support a long term vision that includes the development of units for remote locations ranging from archaoacoustical sites to environmental nature sites to important political listening sites.  Eventually, this acoustic ring could also be accessed by the general public via a virtual reality web browser enabled platform - where people can visit remote sites virtual-acoustically from their own devices.

Initial Outcomes - The Persistence of Sound is installed at CTM, Sonic Acts and other Sound Art festivals:

1. There will be a dedicated 'listening post' where the intention and poetics of this piece will be focused and clear (also visually as directed by microphone and loudspeaker placement).  

2. People will be invited to interact with the tunnel and send sounds through the microphone in the listening post out into the acoustic loop. 

3. An iteration of the Alvin Lucier "I am sitting in a room", but instead of the text, the artist will record and play back, the tunnel into itself, recursively, to get a completely ambient version of the 'multiple room in itself'. 

4. musicians, poets and artists are invited to use The Persistence of Sound  as a performance/recording space

5. interviews and conversations to happen in this special setting.  

Locations and Tech Requirements



A minimum of 5 to 7 connected locations are proposed. 


The locations are chosen based on reverberant and acoustic properties that will make the sound texture interesting whilst not overwhelming to total sound space.  Sound radiated in a reverberant environment will interact with objects and surfaces in the environment to create reflections.  These propagate and subsequently interact with additional objects and surfaces, creating even more reflections.  The artist would like to develop the actual selection of sites together with CTM: whether the spaces are bathrooms, drainage systems, attics, foyers, corridors, concert halls as long as it has the following qualities:


  • should be reverberant

  • have an electric power source within reach

  • have a LAN connection within reach or have a strong wifi signal reception

  • have some poetic/cultural/historic connection to the other sites

  • be somewhat practical to access and troubleshoot

  • be safe - each location will have a speaker, microphone, rasberry pie unit - needs to be locked up or positioned out of reach


Currently I have the following rough technical layout: 

Each location: 

1. Rasberry pi 3 , with added audio expansion (audio in/audio out)  connecting to webtrc hub.

2. USB Microphone

3. Loudspeaker 

Listening Post central hub: 

1. Macbook Pro/Minimac running webrtc router, webrtc mixer, opus codec at 48khz and Ableton Live 

2. 16 channel in/out high quality soundcard 

3.  One speaker for each space - so that the spaces can be presented as an array of sound. (From experience this is more interesting in the listening space than hearing only the mix).

4. LAN connection

5. Some lighting - enough light to be safe, can be intimate warm light, for nice atmosphere

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