Patches n' Pathways is an introduction to Synthesizers by Florence Lin and Chris Thornton.
Chris- Before we start and move into this discussion of synthesis and sound, we want to talk about some key components, that we’re going to be touching back on as we go through this video and video series- and the first one we are going to talk about is pitch or frequency. If we look at in our image, we can see that the wave is repeating and its repeating at a specific rate. Right so, the wave can repeat so many times per second, and that characteristic is what we call “pitch”. The more times per second that the wave repeats, the higher the pitch is, and the less times per second, the lower the pitch is.
Florence- So we perceive a high pitch as (plays a note on synth) … such! a high note! And this is a low pitch, as a low note (plays note on synth).
Chris- Yes, so the next characteristic of sound and electrical signals that we would like to talk about is “voltage” or “amplitude”. If you look at again, our image, you can see that the sound is plotted through time and its also plotted by voltage or amplitude. And that basically translate to the strength of the signal, the strength of the energy that it is putting through.
Florence- So if we’re putting more energy into the system in terms of voltage, through loudness, we’re going to hear an increase in the volume, (plays note) and a decrease- and therefore, on the graph, we’re going to get a higher point on the Y axis.
Chris- And so the final characteristic that we talk about is “waveform”. All of these three characteristics work together in our synth to create the basic sound that we hear, that we are trying to alter. In our image right now we have a wave, thats called a sine wave, its kind of like a normal shaped wave, you see it has just a normal kind of curve, and it just repeats, well each wave has different sound characteristics and we utilize those different waves to create different sounds.
Florence- Sounds are vibrations that can be heard through a listener as they travel through the air. We have an example on the spectrum of what sound looks like graphically.
Chris- So this is a sine wave a simple way, this is kinda the simplest wave you can get. You can see that there is one very high peak, on the left, thats the fundamental frequency that’s telling us what the pitch of the sound is. And then all these other little spikes which is actually not that many, are kinda giving us the timbre of the sound. What does the sound sound like to us? And different sounds have different structures of those overtones or harmonics and thats what gives them different tones. So I’ll play another type of wave, that will have a different harmonic structure. So you see here, this one has its fundamental wave form, then it also has two harmonics right on top of it there. They're almost the same amplitude.
fundamental frequency type of wave. We can only hear a pitch and theres not any harmonic overtones. The next one is going to be triangle. Triangle is going to sound similar to sine wave but with a slight more edge to it and you are getting more harmonic overtones, you can see on the graph here, you've got a lot more spikes. The third ones going to be a square wave, with a square wave you’re getting an odd number of harmonic overtones along with the fundamental frequency. So much buzzier, and a little bit more useful if you are creating a lead, a bass or gameboy sounds. Sawtooth wave; is the most metallic sounding and the most intense of all the wave forms because its the richest in harmonic overtones. You can use this to create some fat lead sounds on a synth, brass, and basically any sort of distorted sound.
Florence- So noise is considered random electronic signals and as you can see in the spectrum here, you're getting just random electronic signals at the same aptitude across the entire spectrum. So there are different types of noise; white, pink and brown. And really the only difference is that you're getting a diminished higher frequency as you go from white noise to pink and then to brown. So the brown’s going to sound a little bit softer and muddier because you are taking out those high frequencies.
Chris- So now we’re going to talk about subtractive synthesis. We really think of this as carving. You have oscillators that are creating rich waveforms, waveforms that are rich in harmonic content, and higher frequencies, and you're going to use tools via the filter and the envelope to chisel out those sounds and shape them into something thats more pleasant or something that you want. And we think of this kinda as similar to the analogy of Michelangelo, chiseling his state figures out of stone. The stone is there, and the statue is just there within it, and all you need to do is free the statue using your filter or your envelop to create a sound that you like...
View the rest of this video's transcript at soundmuseumcollective.org
