FXAlg #908: Pitcher
Algorithm Reference-130
FXAlg #908: Pitcher
Creates pitch from pitched or non-pitched signal
Allocation Units:
1
This algorithm applies a filter which has a series of peaks in the frequency response to the input signal. The peaks
may be adjusted so that their frequencies are all multiples of a selectable frequency, all the way up to 24 kHz. When
applied to a sound with a noise-like spectrum (white noise, with a flat spectrum, or cymbals, with a very dense
spectrum of many individual components), an output is produced which sounds very pitched, since most of its
spectral energy ends up concentrated around multiples of a fundamental frequency.
If the original signal has no significant components at the desired pitch or harmonics, the output level remains low.
The left and right inputs are processed independently with common controls of pitch and weighting. Applying
Pitcher to sounds such as a single sawtooth wave will tend to not produce much output, unless the sawtooth
frequency and the Pitcher frequency match or are harmonically related, because otherwise the peaks in the input
spectrum won't line up with the peaks in the Pitcher filter. If there are enough peaks in the input spectrum (obtained
by using sounds with noise components, or combining lots of different simple sounds, especially low pitched ones,
or several distorting a simple sound) then Pitcher can do a good job of imposing its pitch on the sound.
The four weight parameters, named ÒOdd WtsÓ, ÒPair WtsÓ, ÒQuartr WtsÓ and ÒHalf WtsÓ, control the exact shape
of the frequency response of Pitcher. An exact description of what each one does is, unfortunately, impossible, since
there is a great deal of interaction between them. Here are some examples with a Pitch setting of 1 kHz, which is
close to a value of C6. Weight settings are listed in brackets following this format: [Odd, Pair, Quartr, Half].
[OPQH=100, 100, 100, 100] All peaks are exact multiples of the fundamental frequency
set by the Pitch parameter. This setting gives the most "pitchiness" to the output.
[OPQH= -100, 100, 100, 100] Peaks are odd multiples of a frequency one octave down
from the Pitch setting. This gives a hollow, square-wavey sound to the output.
Khz
dB
dB
Khz
