The core of this week is the multiplier object: *~
Its main function is to multiply audio signals to a number to scale them, or simply mix them with another signal for listening, or for modulating them. These techniques help to produce different sounds.
Multiplier for amplitude control
When a sound is created or recorded, it consists of a sequence of samples, and each sample in the sequence can, in the end, be considered an amplitude value.
If each amplitude value of this signal is scaled to a different number, let’s say to its half, in our perception will sound softer. For example, a sample of 0.8 amplitude, passing through a multiplier to 0.5 will be scaled by half resulting in a new amplitude value of 0.4.
This technique allows us to pass any signal through a multiplier object to scale its amplitude. The multiplier, when used this way, works exactly like a gain~ object, a normal fader for volume (please click on the picture to see it at better resolution).
Multiplier used to multiply by a sinusoidal sound at 5 Hz to one (left) and by 0.5 (by half, right). Note the changes to the wave visualisation
Multiplier used to mix signals
Multiplier can be used to mix signals together. In this case, the value in the right inlet could just be 0.5 to make sure that the sum of the two signals never exceeds 1, which could lead to distortion. [Ideally, also two additional multipliers should be added to each sound to control the incoming mixing point for the mixing multiplier]. By mixing signals created with different waveforms, or with the same waveform but set at different frequencies (as in the picture below), it is possible to obtain more complex sounds (see Synthesis page).
In sum, a multiplier allows you more precision control over the amplitude as opposed to a normal fader, although you need to become accustomed to the concept of amplitude sitting between the 0.-1. value range, and to controlling via number box and not via a simpler graphical object as a fader.