This post is part of a series of notes and exercises for a summer camp on making musical instruments with Arduino and Pure Data.
Author Christopher Paul Curtis writes in Elijah of Buxton, “Believe some to none of what you hear and only half of what you see.” The intended target of Curtis’ wisdom is gossip and related sociological issues, but we can apply it to physical sound as well. Our ears are easily tricked, and sometimes we need to see sound to make sense of it.
In this exercise, we will visualize the waveforms of pure frequencies using Pure Data’s array object. In particular, we will create a patch that looks like this:
An array is two things in Pure Data. First, it is a container that stores many numbers. Second, it is a graph of those many numbers.
Follow these steps to produce your patch:
tabwrite~object. This command is an abbreviation of table write. Write to the
wavearray by typing
tabwrite~ wavein the object box. This expression passes
waveas a parameter.
osc~to the inlet of
bngobject. This command is an abbreviation for bang. If
tabwrite~is given a number, it stores it. If it’s given a
bng, it plots the numbers it has stored.
bngto the inlet of
tabwrite~. Leave Edit Mode and generate a sound. Click the
bngto view the waveform.
bng, and observe how the waveform changes.
After you get your patch working, answer the following questions on a piece of scratch paper.