| Names | Loudness |
|---|---|
| Class | Linear filtering |
| Products | |
| Details | Bass and treble boost approximating a suitable low amplitude Fletcher‐Munson curve. Originally meant to equalize the psychoacoustic difference caused by listening music at a low level. Nowadays supplanted by sheer bass boost. |
| Strong and weak points |
| Names | Boom filtering, subsonic filtering, rumble removal |
|---|---|
| Class | Linear filtering |
| Products | |
| Details | A shelf filter which cuts subsonic frequencies (cutoff at about 20‐30Hz). Used to attenuate the drive hum of a turntable and to shield speakers from overload in case somebody hits the turntable. |
| Strong and weak points |
| Names | Excitation, enhancement, finalization, maximization |
|---|---|
| Class | Waveshaping, dynamics |
| Products | |
| Details | A family of methods which increase the perceived loudness and
energyof sound. Used to bring forth a given part of a mix or to add punch to commercial sound material. In vogue among producers of commercial pop. |
| Strong and weak points |
| Names | Synthetic, spread or enhanced stereo or surround |
|---|---|
| Class | Linear filtering, dynamics |
| Products | |
| Details | A combination of psychoacoustic filtering, linear filter networks to achieve phase shifts and/or reverberation and dynamics processing to steer signals in reasonable places in the stereo field. Used to emulate true, discrete channel surround sound with stereo sound sources or to play back mono sound through as stereo. |
| Strong and weak points |
| Names | Feedback elimination, howl suppression |
|---|---|
| Class | Adaptive linear filtering, pitch shifting |
| Products | |
| Details | Used to eliminate howl resulting from PA‐microphone feedback in live performances. Works either by slight pitch shifting (making signals at resonant frequencies drift out of them before the feedback becomes noticeable), by selectively attenuating frequency ranges which are seen to be prone to feedback (the more high tech approach) or both. |
| Strong and weak points |
| Names | De‐essing |
|---|---|
| Class | Linear filtering, dynamics |
| Products | |
| Details | Used to even out sibilant sounds recorded through microphones (these are often a real problem since they tend to have high loudness). Basically a downward compressor driven by a control signal which emphasizes the high‐mid to low‐high frequency ranges which contain most of the sibilance. |
| Strong and weak points |