
One of the type of Objects in Praat. A MixingMatrix shows a mapping of the channels of an input Sound to the channels of an output Sound. A channel in the input sound is called an input channel. Each output channel is a linear combination of input channels.
The mixing of input channels can be written as the matrix multiplication R=M·S. Here S is the matrix that represents the input sound, with numberOfInputs rows and numberOfSamples columns. Each row in S corresponds to one input channel. M is the numberOfOutputChannels× numberOfInputs MixingMatrix and R is the numberOfOutputChannels× numberOfSamples matrix that is the result of the mixing.
Row i in the MixingMatrix M therefore represents the weights m_{ij} of the different input channels j in output channel i, the number of rows of M determines the number of output channels in the resulting R. Column j in M represents the weight factors m_{ij} of input j in the different output channels i.
Given the following stereo Sound with a tone of 300 Hz in channel 1 and a tone of 600 Hz in channel two:
stereo = Create Sound from formula: "s", 2, 0, 1, 44100, "sin(2*pi*row*300*x)"
mm1 = Create simple MixingMatrix: "mm1", 2, 1, "1 0"
selectObject: mm1, stereo
Mix
mm2 = Create simple MixingMatrix: "mm2", 2, 1, "0 1"
selectObject: mm2, stereo
Mix
mm3 = Create simple MixingMatrix: "mm3", 2, 1, "1 1"
selectObject: mm3, stereo
Mix
mm4 = Create simple MixingMatrix: "mm4", 2, 2, "1 0 1 0"
selectObject: mm4, stereo
Mix
mm5 = Create simple MixingMatrix: "mm5", 2, 1, "0.5 0.5"
selectObject: mm5, stereo
Mix
mono = Create Sound from formula: "s", 1, 0, 1, 44100, "sin(2*pi*300*x)"
mm6 = Create simple MixingMatrix: "mm6", 1, 2, "1 1"
selectObject: mm6, mono
Mix
mm7 = Create simple MixingMatrix: "mm7", 2, 2, "0 1 1 0"
selectObject: mm7, stereo
Mix
© djmw, September 7, 2017