Synthesis PDF

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Summary

Lecture notes taken for Effects Processing and Synthesis. Covers information about effects processes, including equalization, compression, reverb, delay, panning, etc. and how they work within a digital audio workstation. Taught by Dr. Christopher Biggs....

Description

What is Synthesis? ● When we do synthesis we are creating a sound w/o storing or manipulating a pre-existing, sampled sound. ● Synthesis is the process of generating “in the box” ● There are both physical (hardware) and virtual (software) synthesizers ● Resynthesis refers to some type of process that remakes a recorded sound, such as granular resynthesis or spectral resynthesis. Why do Synthesis? ● No noise ● Can make sounds that no physical object can replicate ● Isolation and hyperrealism in movies/video games/commercials ● Unique Sounds ● Physical Modeling ● Replace acoustic performers (timbres) ○ Mock-ups of acoustic music ○ Replicate the specific sounds of acoustic music (not in electroacoustic academic music in general) ● Fill the roll that acoustic instruments play in acoustic music with synthesized sounds ○ Less common in electroacoustic academic music

Basic Materials I: Oscillator ● Oscillator ○ A device that produces a regular audio signal that is typically a simple waveform ○ These sound quite artificial and have been employed intentionally to sound artificial ● Typical waveforms ○ Sine Tones ○ Wave Types ■ Sine, sawtooth (up), Sawtooth (down), Pulse, Square, Tri, etc Basic Materials II: Noise ● Random sine tones across the audible frequency spectrum ● Noise Types ○ White noise ■ Equal amplitudes across the entire spectrum ○ Pink noise ■ Equal amplitudes within each musical octave ○ Brown noise ■ More decrease (6dB per octave) as we ascend in the frequency ○ Blue Noise ■ Increase of 3dB per octave

Bais Process I: Scaling Signals ● As we discussed, scaling signals involves multiplying a signal we want to hear by a signal that we don’t want to hear that is stagnant or slowly (relatively speaking) changing ● The goal of this process is to… ○ Hear the sound at the correct volume ○ Automate the volume of the sound ■ Fade in/out ■ Amplitude envelope ● The scaling signal, the signal by which the signal we want to change the volume of is multiplied Basic Process II: Mixing Signals ● As we discussed, mixing signals is the process of ADDING two or more signals together Basic Process III: Amplitude Envelope ● This is where we multiply a signal in order to scale its volume in a manner commensurate w/ how real world sounds behave ● ADSR ● This becomes very important in synthesis because the sounds we are synthesizing are typically just constantly being made by oscillators, we need to give them a shape Basic Process IV: LFO ● Modulation ○ The multiplication of an audio signal by another, rapidly changing audio signal ● An LFO is going to modulate some feature of another signal, such as the amplitude, frequency, or phase (or anything else) at a rate that is less than 20 hertz. ● An LFO is going to be a simple waveform, most typically a sine tone ● Parameters of an LFO ○ Wave shape ○ Frequency (vibrato) ○ Depth (tremolo)

Additive Synthesis ● This is the process of combining (mixing) simple waveforms in order to create a sound ● There will likely be other processes involved too… ○ Scaling (ADSR) ○ Filtering ○ LFO Subtractive Synthesis ● We begin with a complicated sound and make it simpler (in terms of the spectrum, we subtract components) ● The processes involved are going to be: ○ Generation of complicated waveform (noise or noise-like filtering) Subtractive Synthesis vs. Additive Synthesis ● These terms were coined in somewhat simpler times… ● Most modern synthesisers do both and are way too complicated to label them as one or the other Pole? ● A 1-pole filter has a gradient of -6dB/octave, a 2-pole filter dampens the signal -12 dB/octave Comb Filter ● Comb filters change the sound by delaying the signal by a few ms…

Macro Controls in Absynth ● In order to automate a parameter, you need to assign it to a macro controller within Absynth.

Massive ● Oscillator and noise generators ● Routing oscillators to filter 1 and/or filter 2 ●

WT. position: Wave Table Position ○ Changes how to software changes how the waveform is presented

Modulation ● The Concept of modulation has already been discussed ● Modulation results from multiplying, as does scaling, but the signals will be bipolar, not unipolar (generally). ● We are going to do the same basic process as an LFO, but we are going to use modulators

Software Samplers ● What is a sampler? Kontakt ● Adding premade sounds...