An Overview of Audio Effects
This week we’re taking a step back to the basics in order to give our beginner students and readers an overview on audio effects and how they work. If you’re just starting out on your audio production journey, you’ve most likely come across effects in your gear or software. These might be delay, reverb, distortion, compression, phase, flange, pitch-shift, ring modulators or filters. This article aims to get you familiar with these terms and what these devices do. In future installments of this series we will get a bit deeper on specific types of effects (as some subjects such as reverb require an article of their own.) For now we begin at the beginning…
What are Audio Effects?
Audio effects are devices (analog or digital) that are used to intentionally alter how a musical instrument or other audio source sounds. Effects can be subtle or extreme and they can be used in live or recording situations. A good example of audio effects are the “stomp-boxes” that many electric guitarists use to realize their desired sound. By chaining together many different types of effects units a musician can sculpt a unique tone. Almost all popular music benefits from creative use of effects, the only exception being an all-acoustic show (and even then there are usually effects involved). All commercial music is enhanced with effects and electronic music makes liberal use of these devices. With proper use they can really enhance your sound and take the listener to new sonic spaces.
A Brief History of Audio Effects
Modern day effects are all a result of the evolution of technology and the advent of recorded sound. Around the Mid 1940′s recording engineers started to use reel to reel tape machines to create delays, echos and sound effects. In addition to tape, microphone placement and movement were found to create sounds that had not previously been recorded. In 1948 Harry DeArmond, creator of the first guitar pickup, created the first stand-alone effects processor called the Trem-Trol by running the electric current of the signal through liquid to create a tremolo sound. This device was used by Bo Diddley and led to more development in the guitar industry of the 1940′s and 50′s where guitar amplifiers started to introduce vibrato and reverb effects. Reverb was initially created by driving an electrical signal into a metal plate or spring to create multiple echos or reflections of a sound.
Back in the studio, recording engineers started to use echo chambers to create echo effects or a unique tone to their recordings. Echo chambers were usually long, low rectangular spaces made from sound-reflective materials such as concrete. They were fitted with a loudspeaker at one end and a microphone at the other to create an echo effect that was used on many recordings to enhance vocals. As they were often custom-made, these echo chambers became the sound signature of a given studio at that time. As technology developed, many reverb devices allowed for electronic re-creation of the echo chamber effect. Equalizers and compressors arrived in the studio in the 1950′s and 60′s with the Pultec equalizer which defined the sound of many recordings of that era.
Hardware and Software Effects
Today audio effects devices come in both physical and digital form. Audio signals in electrical format are processed with physical (analog) hardware whereas audio signals in binary format (digital) are processed mathematically by software. Both methods can achieve similar results. In the physical world, effects are usually rack-mounted devices that have cables running to and from a mixing board or they can be something like guitar effect pedals which receive signal from the instrument and alter the signal as it flows to a mixer. On the digital side you can find effects in most music recording software packages. DAWs such as Ableton, Logic, Cubase and ProTools all come with audio effects built-in. Other software packages like Reason, Maschine, Traktor, Audacity, Peak, and Soundforge also come with audio effects. Audio effects are often simple devices that do one specific thing to a sound, although multi-effects processors are also popular for those who want many different effects in one package. It is also worth noting that many instruments (especially synthesizers) come with effects built-in to the machine.
Examples of Audio Effects
For each of the following types of effects we have provided an audio example to hear what the effect sounds like. This beat was made in Maschine and run through various effects in Ableton Live. The original (un-altered) beat comes first and each audio example after that is effected.
Original “Dry” Beat
Dynamic effects (aka amplitude effects) modify the volume of an instrument. These effects include compressors (which increase the loudness of a signal or stabilize volume), limiters (which limit the volume), and noise gates (which aim to eliminate artifacts like hum, hiss and vocal pops.) Dynamic effects can greatly enhance your mix but they are sensitive devices that require attention to detail. Compressors are widely used today in commercial music and sound louder for television and radio use.
Distortion effects can create a harmonic (warm) or inharmonic (gritty) sound by amplifying an audio signal until it clips (gets too loud and cuts the shape of the waveform.) By changing this waveform shape the distortion effect creates overtones which color the sound. This is a popular effect/sound in rock music and it’s become widely-used in modern electronic music as well. Distorted signals tend to cut through a mix and bring warmth or grit to a tone.
Time based effects alter the timing of a signal which can create short or long bursts of sound. These effects include reverb, delay and echo. These are among the most popular effects in electronic music with reverb and delay used liberally on most recordings. Reverb effects sometimes aim to re-create the sound of an acoustic space and they are sometimes based on “plate reverb” or “spring reverb” effects – which we will discuss further in an upcoming article.
Filter effects alter the frequency content of an audio signal. This is achieved by boosting or cutting specific frequencies in that signal. Popular filter effects include the Wah Wah pedal (used often in funk, ska, and psychedelic music) and equalizers (found on many devices from mixers to your car stereo.) Low-pass or Hi-pass filters appear on some synthesizers and audio mixers.
Modulation effects create unique tonal properties by multiplying and altering a signal. Some of these effects use a “carrier wave” as a modulator to change an audio signal. Others will multiply your audio signal and then alter one of those versions to create unique tone. Modulation effects include chorus, flanger, phaser, ring modulator, tremolo, and vibrato. The ring modulator in particular is a unique sounding device which was used to create the “imperial code” in Star Wars: The Empire Strikes Back.
Ring Modulated Beat
Pitch / Frequency
Pitch and Frequency effects include pitch shifters and harmonizers. These effects modify the pitch of a sound by adding new frequencies to a signal or by simply altering the pitch. Pitch-shifters transpose (raise or lower) the note that is played at certain intervals. A harmonizer is a pitch-shifter that adds more notes to create harmony.
Frequency Shifted Beat
Michael Walsh is the Editor of Dubspot’s Blog, a producer of audio/visual art and a journalist living in Southern California. Read more of his work at soundsdefygravity.com