Signal Processing


Topics This Week


In a general sense, we could say that any time audio is converted from acoustic energy into electrical energy, sound is being processed. Any device in the audio chain, from a microphone to amplifiers and speakers, alters or colors the original sound in some way. Practically though, we'll limit our discussion to devices intended to manipulate sound in some way, either to creatively alter a signal or to correct a problem.


Effects Categories

Dynamics processors

Dynamics processors affect the loudness of a sound over time, and help us correct levels, increase the sustain of decaying sounds, and filter out background noise. Follow the link for a more detailed explanation.

Spectrum Processors

Spectrum processors are filters or equalizers used to alter the harmonic content of a signal. These processors affect the tone color of a sound and allow us to equalize audio, create special tone-color effects like wah-wah, and help us create clarity in a mix. Generally a filter will boost or cut selected frequencies by an amount expressed in dB. The range of frequencies effected is referred to as bandwidth or "Q." Bandwidth is usually expressed in octaves. Follow the link for a more detailed explanation.

Types Include:

20 Hz, 40 Hz, 80 Hz, 160Hz, 320Hz, 640Hz, 1.25kHz, 2.5kHz, 5kHz, 10kHz, 20kHz.

Time-based processors

These processors repeat the signal over time and create a variety of musical effects such as reverb, chorus, flanging, echo, slap-back delay, etc… Follow the link for a more detailed explanation.


Processor Architecture


This Week's Assignment

Assignments:

Try the specific effects processors in your version of Reason. What can you use these for?

What type of effect would be useful for you to use with your principle instrument? Use the Web to research some of the types of effects devices available today and report back to the class discussion area found in Course Companion.


Review Questions

What are the different type of dynamics processors and what could they be used for?

Think about the characteristics of the different types of filters we've talked about.

What are the different types of Time-based Processors and what could they be used for?

What's the difference between a Flanging and Chorusing?

What's the difference between a Delay effect and Reverb?

What parameters can be controlled when we add Reverb to a signal?

The way we describe Signal Processing is somewhat subjective, but in general what processors would you use to archive the following results:


Signal Processor Vocabulary

Band Pass Filters
Bandwidth or Q
Cents
Chorus
Compression
Compressor
dB
Decay
Doubling
Dynamic Range
Early Reflection
Equalizers
Expansion
Filters
Flanging
Gate
Graphic EQ
High Pass Filter
Limiter
Low Pass Filter
Multi-effects
Noise Reduction
Parametric EQ
Pitch
Early reflections
Ratio
Reverb
Shelving EQ
Slapback
Threshold
Transients