OSSTS (Oslo Sound Space Transport System)

The Oslo Sound Space Transport System OSSTS is an interactive sound composition that allows you to experience Oslo in a way never before heard.

In OSSTS you can explore Oslo's sounding space. You can hear your own voice or other performed sounds 'activate' Oslo's real acoustic architecture. You can travel through surreal spaces and pause inside specially made electroacoustic compositions. With the interactive interface you can recompose the sound of Oslo and explore surreal Oslo-inspired soundworlds made by OSSTS's composer, programmer and designer Natasha Barrett.

OSSTS was commissioned by OCEAN Research and Design Association.

How OSSTS works

Our sound space consists of two elements: sound 'sources' and sound 'reflections'. With our ears, sound sources and sound reflections allow us to recognise familiar spaces. Sources range from single sounds to complex cacophonies of busy scenes. Sound reflections are created when a sound wave reflects off a surface, and the reflections come together making what we commonly know as reverberation. We are most familiar with indoor reverberation, for example the sound of a bedroom in contrast to that of a cathedral. Outdoors there are also sound reflections and reverberation, only the results are subtler than indoor acoustics and often go unacknowledged. Sound reflects off grass, stone, walls, is filtered through trees and refracts in the atmosphere.

Reverberation can be measured and captured in 3D audio using ambisonics technology. These measurements capture the reflections from all directions and provide a 3D sound spatial picture of the room otherwise known as a 3D 'impulse response'. By using a process called 'convolution' we can make any source appear to sound inside any real space.

In OSSTS the reverberation of many of Oslo's indoor and outdoor spaces were captured, along with an even greater number of 3D recordings of the general sound environment. These materials further provided inspiration for the composition of surreal spaces and longer compositions.

The interface for OSSTS allows you to navigate through a map of Oslo's spaces, interact in real-time experiencing the reverberation, and explore the surreal spaces and compositions. Focusing on our ears, we experience Oslo in a way never before heard.

The OSSTS interactive programme

OSSTS uses six types of audio. For each space there is one or all of the these sound types:

• 3D impulse responses.
• Composed mono sounds that are used as sound sources for real-time convolution.
• Short compositions and surreal spaces made in ambisonics.
• 3D environmental recordings (these help to set the scene).
• User made sounds convolved in real-time (microphone input).
• Short, spoken text indicators for key spaces, used as sound sources for real-time convolution. (Text is in English but a provision for a Norwegian local dialect option has been programmed into the interactive software).

In OSSTS the spaces are arranged in a map. From each space there is complete freedom as to where the user chooses to travel and the speed at which they move. The transitions between spaces, impulse responses, input sounds, real environment recordings and composed materials are all calculated in real-time and based on real acoustics: the closer you are to the centre of a space or to the point of a source, the louder and brighter the sounding results. As you move further away the result becomes gradually quieter and a little more dull or distant sounding.

Likewise, all sound is spatialised in real-time in relation to the moving listener. This means the sound sources remain stable, just as in reality. For example, if the listener moves to the left, in relation to the listening point the sound source will appear to the right. Likewise if the listener were to rotate clockwise, in relation to the listening point the sound source will appear to rotate anticlockwise.

The OSSTS map is laid out in a grid-like format. Although not exact to Oslo's real geometry this allows the user to, for example, move rapidly from Ring-3 to the Vigelund's Mausoleum without a 30-minute bus ride! Within this grid, the distance between points is carefully chosen to bring out the optimum real-time mix between adjacent sounds. For example, complex sounds located too close together will simultaneously sound at a high volume resulting in a messy real-time mix. If located too far apart, the feeling of relation and transition will be lost.

Longer composed materials are found towards the edges of the map.

Different spaces contain different amounts of information for a user to explore.

OSSTS is programmed in MaxMSP. The first version of the interactive interface is a simple map of colour-coded points indicating the centres of each space or sound. The user explores using the Space Navigator 3D mouse. This simplified visual map and controller are temporary solutions necessary for the composition and programming phase. In the exhibition project development with OCEAN Research and Design Association, graphics and controllers will be designed, developed and constructed.

The spaces

Here follows a list of spaces found in OSSTS:

• Oslo Central Station – inside.
• Oslo Central Station – outside.
• Botanical Garden – between zoological and geological museums.
• Botanical Garden – in front of the steps leading to Great-granny's Garden.
• Tøyen swimming pool – outside front entrance.
• Tøyen swimming pool – in the reception.
• Tøyen swimming pool – beside the main pool.
• Tøyen swimming pool – beside the outdoor pool.
• Cathedral – outside front entrance.
• Cathedral – inside.
• Aula – outside in the main square.
• National Theatre – outside in the square beside the fountain.
• National Theatre – Arne Eggen West entrance sound sculpture and tunnel.
• Town Hall – outside.
• Ibsenkvartalet – outside in the square between the high buildings, surrounded by construction work.
• Akerselva river – close to the Architect's school.
• Architect's school – outside main entrance.
• Architect's school - inside the foyer.
• A garden on the outskirts of Oslo.
• Inside an old wooden house from the 20's / 30's.
• Inside a small tiled bathroom.
• Vigeland's Mausoleum – inside.
• National Opera – outside on the sea front.
• National Opera – on the roof.
• National Opera – in the foyer.
• National Opera – in the cloakroom.
• National Opera – in the main opera hall.
• Inner city green lung.
• Traffic: Ring-1, Ring-2, Ring-3, Trams, buses and pedestrian crossings from Karl Johan towards the harbour.

Special thanks to Kare Nordstoga for organ samples and to the Oslo Central Station, Botanical Garden, Oslo Cathedral, Vigelund's Mausoleum and the National Opera for out-of-hour access to make indoor impulse responses. Other credits: vocal samples from a recording session with Jane Manning / Natasha Barrett in 1997, and computer manipulations from the Sweet Sensations project (Barrett, 1997 / 1998). Other vocal samples: Natasha Barrett, Birger Sevaldson, public address announcements at Oslo S, National Theatre station, Opera foyer, and voices of anonymous passers by. Composition, sound manipulations and programming, Natasha Barrett, 2012.

Click here for more info on the technical side