filtRespShelf

Frequency response (transfer function) of a shelving filter.

Computes the complex frequency response function corresponding to a shelving-filter transfer function.

Syntax

h = filtRespShelf(f,n,f0,GdB,shelfType)

h = filtRespShelf(f,n,f0,GdB)

filtRespHPQ(__)

filtRespHPQ()

Description

h = filtRespShelf(f,n,f0,GdB,shelfType) returns the frequency response column vector computed at the frequencies supplied in f (in Hz). The order of the shelving filter is given in n, where admissible values are 1 or 2. The shelf has a crossover frequency of f0 (in Hz) and a gain GdB (in dB). The value of GdB can be positive or negative.

The midpoint gain at f0 is chosen such that it is the arithmetic mean of the extreme gains (1 and G = db2mag(GdB)) on a decibel scale.

If GdB is a row or column vector containing a number of values, the frequency response is returned as a matrix of column vectors.

A high shelf filter is specified by setting shelfType to be one of the following: 'H', 'HIGH'.

A low shelf filter is specified by setting shelfType to be one of the following: 'L', 'LOW'.

If shelfType is omitted or is empty ([]), then a high shelf filter is the default choice.

filtRespShelf(__) with no output arguments plots the magnitude and phase response of the shelf filter (its frequency response).

filtRespShelf() with no input arguments plots the magnitude and phase response of two sets of example shelf filters. No output is returned.

Reference

Valimaki, Vesa; Reiss, Joshua D. (2016). All About Audio Equalization: Solutions and Frontiers. Applied Sciences, Volume 6, Issue 5, 129. https://doi.org/10.3390/app6050129 (Open Access)