Amplitude is inversely proportional to distance

Our tympanic membrane (a.k.a. our eardrum) and a microphone are both devices that measure sound intensity. When a sound arrives at our eardrum or at the diaphragm of a microphone, either of which has a certain surface area, the power in that area (i.e. the intensity) is detected. However, the intensity of a sound, as measured by an eardrum or a microphone, will differ depending on the distance from the sound's source, because the sound is being emitted from the source in all directions.

Trapezoidal control signals

The trapezoid~ object outputs a trapezoidal shape, rising linearly from 0 to 1 in a certain fraction of its time, then staying at 1, then falling linearly back to 0 in a fraction of its time. Its timing is driven by a control signal at its input, one that goes in a straight line from 0 to 1; so a phasor~ or a line~ is the obvious choice for input to trapezoid~. As the input goes from 0 to 1, the output draws the designated trapezoidal shape.

Interface for a flanger

This patch shows an appropriate interface for a flanger, including dials to control delay time, flanging rate, flanging depth, and control over the mix between the dry (unaltered) and wet (altered) signal. Control over the dry/wet mix is a good thing to include in most audio effects.

Simple demonstration of flanging

The technique of flanging in computer music refers to a changing delay time applied to a sound, usually by modulating the delay time with a low-frequency oscillator (LFO). The continuously changing delay time causes a subtle—or not-so-subtle—change in the pitch of the sound. When the flanged sound is mixed with the original sound, the two sounds interfere in continuously changing ways, creating a charactistic modulated filtering effect.

Abstraction for S-curve crossfading

A good way to mix two sounds is to give one sound a gain between 0 and 1 and give the other sound a gain that's equal to 1 minus that amount. Thus, the sum of the two gain factors will always be 1, so the sum of the sounds will not clip. When sound A has a gain of 1, sound B will have a gain of 0, and vice versa. As one gain goes from 0 to 1, the gain of the other sound will go from 1 to 0, so you can use this method to create a smooth crossfade between two sounds.