jasch

icst-releases-ambisonics-externals-for-maxmsp

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Centre de Recherches et de Formation Musicales de Wallonie asbl

_____________________________
Patrick Delges

Centre de Recherches et de Formation Musicales de Wallonie asbl
http://users.skynet.be/crfmw/max


would anyone be willing to explain how ambisonics works in layman's terms? How would a four-channel ambisonic setup differ from quad panning based on simple level differences among four channels?

would anyone be willing to explain how ambisonics works in layman's terms?  How would a four-channel ambisonic setup differ from quad panning based on simple level differences among four channels?


To really get it you want to read the article in Computer Music 

Journal (Myatt A and Malham DG: Three Dimensional Sound 

Spatialisation Using Ambisonic Techniques, Computer Music Journal, 

Vol.19 No.4, MIT Press, Cambridge MA,USA, 1995, pp58-70.

Briefly, the point of ambisonics is that it is based on the 

mathematical technique of sampling the surface of a sphere, whis can 

be represented by four signals: X = front/back, Y = left/right, Z = 

up/down and W = omni - for largely historical reasons to do with the 

soundfield microphone this is known as B-format. A few simple 

formulae involving sines and cosines (very easy to implement in Max 

using cycle~ objects) enable the four signals to be decoded for any 

This technique was developed by the mathematician and sound expert, 

Michael Gerzon in the 1970s, which led to the development of the 

Soundfield Microphone, which enables a soundfield to be recorded and 

encoded into B-format (A-format is the output of the microphone itself).

Level panning only works properly for speaker angles of 60 degrees or 

less (and is also very dependent on correct location of the 

listener), so if there are four speakers the average angle is 90 

degrees, and level panning will always be sub-optimal. However, 

ambisonic signals can decode correctly over four speakers, and they 

don't even have to be in an exact square. Larger numbers of speakers 

will give greater accuracy for a larger number of people, as well as 

enabling three dimensional positioning. Moreover, the same B-format 

recording can be decoded for any number and positions of speakers, so 

is easily adaptable to different listening conditions.

Much more details on the ambisonics website and the Wiki article (see 

On 22 Apr 2007, at 06:43, Joseph Grimm wrote:

> would anyone be willing to explain how ambisonics works in layman's 

> terms? How would a four-channel ambisonic setup differ from quad 

> panning based on simple level differences among four channels?

Lawrence Casserley - lawrence@lcasserley.co.uk

Lawrence Electronic Operations - www.lcasserley.co.uk

Colourscape Music Festivals - www.colourscape.org.uk

To really get it you want to read the article in Computer Music  
Journal (Myatt A and Malham DG: Three Dimensional Sound  
Spatialisation Using Ambisonic Techniques, Computer Music Journal,  
Vol.19 No.4, MIT Press, Cambridge MA,USA, 1995, pp58-70.

Briefly, the point of ambisonics is that it is based on the  
mathematical technique of sampling the surface of a sphere, whis can  
be represented by four signals: X = front/back, Y = left/right, Z =  
up/down and W = omni - for largely historical reasons to do with the  
soundfield microphone this is known as B-format.  A few simple  
formulae involving sines and cosines (very easy to implement in Max  
using cycle~ objects) enable the four signals to be decoded for any  
number and configuration of speakers.

This technique was developed by the mathematician and sound expert,  
Michael Gerzon in the 1970s, which led to the development of the  
Soundfield Microphone, which enables a soundfield to be recorded and  
encoded into B-format (A-format is the output of the microphone itself).

Level panning only works properly for speaker angles of 60 degrees or  
less (and is also very dependent on correct location of the  
listener), so if there are four speakers the average angle is 90  
degrees, and level panning will always be sub-optimal. However,  
ambisonic signals can decode correctly over four speakers, and they  
don't even have to be in an exact square. Larger numbers of speakers  
will give greater accuracy for a larger number of people, as well as  
enabling three dimensional positioning. Moreover, the same B-format  
recording can be decoded for any number and positions of speakers, so  
is easily adaptable to different listening conditions.

Much more details on the ambisonics website and the Wiki article (see  
above)

> would anyone be willing to explain how ambisonics works in layman's  
> terms?  How would a four-channel ambisonic setup differ from quad  
> panning based on simple level differences among four channels?

Lawrence Casserley - lawrence@lcasserley.co.uk
Lawrence Electronic Operations - www.lcasserley.co.uk
Colourscape Music Festivals - www.colourscape.org.uk

ICST releases Ambisonics Externals for Max/MSP