Sound Effects (SFX)
Sound effects are sounds that were generated or enhanced artificially.
Techniques
- filtering – Frequency ranges are emphasized or attenuated using low-pass, high-pass, band-pass or band-stop filters.
- equalization: Different frequency bands are attenuated or boosted to produce desired spectral characteristics. Equalization is a form of filtering.
- echo: Simulates the effect of reverberation. One or several delayed signals are added to the original signal.
- reverse echo – a swelling effect created by reversing an audio signal and recording echo and/or delay whilst the signal runs in reverse. When played back forward the last echos are heard before the effected sound.
- chorus: Conveys the effect of multiple voices. A delayed signal is added to the original signal with a constant delay and optionally pitch shifted. The delay has to be short in order not to be perceived as echo.
- flanger: A delayed signal is added to the original signal with a continuously variable delay (usually smaller than 10 ms). This creates an unusual sound.
- phaser: The signal is split, a portion is filtered with an all-pass filter to produce a phase-shift, and then the unfiltered and filtered signals are mixed. This creates and unusual sound.
- overdrive: Can be used to produce distorted sounds. The most basic overdrive effect involves clipping the signal above a threshold.
- pitch shift: Shifts a signal up/down in pitch.
- time stretching: The opposite of pitch shift, that is, the process of changing the speed of an audio signal without affecting its pitch.
- resonators: Emphasize harmonic frequency content on specified frequencies.
- synthesizer: Generate new sounds by either imitating natural sounds or creating completely new sounds.
- modulation: to change the frequency or amplitude of a carrier signal in relation to a predefined signal.
- compression: The reduction of the dynamic range of a sound to avoid unintentional fluctuation in the dynamics.