The topics this week are time based effects and we will explore the following focus areas:
REVERB | DELAY | PITCH | STRETCH TOOLS
FOCUS AREAS IN DEPTH
OVERVIEW SPECIFICS EXPLORE
REVERB - As recalled from earlier sections in the course reverberant sounds are densely spaced reflections created by random, multiple and blended repetitions of a sound. When processing the sound in post production, effects give additional control with the mix in the blending of the dry sound (input with no reverb) with the wet sound (processed sound with reverb). Reverberation can be reinforced and created by using various methods both by acoustic and physical applications or digital simulation processing.
Digital - Once incorporated in studios as standalone physical processors acting as mini computers to process each reflection thousands of times per second. Reverb units are now convenient plugins in our DAWs. The digital reverb can simulate nearly every space imaginable. Predelay allows the user to finely tune when the reflections begin. This control helps to closely mimic actual physical spaces creating a more natural environment between direct and reflected sounds.
Plate - Plate reverb is created by a large physical device with a metal sheet suspended in a frame. An exciter driven by the original sound (dry) is used to vibrate the metal plate. Special contact mics are attached to the unit to capture the new reverberant sound (wet) to be re-recorded and later blended the original in the mix.
Chamber - Reverb chambers are physical rooms specially designed to reinforce reflections in the space. The rooms have non parallel walls that effect the sounds in a more natural way due to their acoustic properties. The pitfall with a true reverb chamber is the cost and space needed to build a proper chamber as they are very large and need massive amounts of isolation. With high quality digital alternatives in recent years, engineers are able to affordably and more naturally create the reverberant spaces with plugins “in the box” during the mix.
DELAY - Refers to the time between the original sound and the sounds repetition. In creating various parameters to set several delays, numerous effects can be achieved. Delay is utilized in many different processors and, like reverb units is utilized to simulate previously used physical techniques developed with analog tape.
Echo - This type delay creates a discrete repetition of a sound. This resemble a natural echo as described earlier in course as a distant repeat of a single direct sound. Similar to reverb, delay times can be modified to create a the perception of a large or small space.
Chorus - Is a doubling effect that is generally used on vocals to recirculate the sound. The delay times range from subtle support for a single voice, or can be modified in greater ways to make a small group sound similar a large choir.
Flange - Is meant to simulate an analog effect of playing back two tape machines into a single recorder by delaying one of the players in manually applying pressure to the flange arm of the tape player as the tape is fed through the machine. Digital flangers create more precise control of how the sound can be delayed and also offer controls in correcting phase issues that can emerge from this type of delay method.
PITCH - Again revisiting the discussion of frequencies and human perception of sound, high frequencies are perceived as having a high pitch, conversely low frequencies are perceived as lower pitches. The higher the frequency the more vibrations per second the sound wave has. Pitch effects help to alter these physical properties of the original sound and are extremely useful and sometimes criticized for their use (or overuse) in pop music. When used by sound effects designers, manipulating the pitch characteristics of a sound can dramatically change a sound into something totally new to achieve various effects for cinematic applications.
Shift - Pitch shifting is the transposing of the sound being sped up (increasing pitch) or slowed down (lowering pitch). Many times these effects are destructive as they alter the overall time physically from the original sound.
Correction - Pitch correction is another similar type of shifter, but is based on pitch ratios. These ratios are able to simulate notes to allow the effect to “harmonize” the original sound, effectively changing and correcting notes from instruments and vocals in musical applications. Since the 1990s these pitch correction devices have been commonly referred to as “autotune” due to their prolific use in pop music.
STRETCH TOOLS - Time compression and expansion can be a subset of pitch effects, but also a non destructive tool in the DAW. In the multitrack view if the tool is enabled, clips of audio can be expanded (lengthened) or compressed (shortened) in time to fit pacing without destructively changing the original pitch of the sound.