designParamEQ
Design parametric equalizer
Syntax
Description
[
specifies options using one or more B
,A
] =
designParamEQ(___,Name,Value
)Name,Value
pair
arguments.
Examples
Design Two-Band Parametric Equalizer
Specify the filter order, peak gain in dB, normalized center frequencies, and normalized bandwidth of the bands of your parametric equalizer.
N = [2, ... 4]; gain = [6, ... -4]; centerFreq = [0.25, ... 0.75]; bandwidth = [0.12, ... 0.1];
Generate the filter coefficients using the specified parameters.
[B,A] = designParamEQ(N,gain,centerFreq,bandwidth,"Orientation","row");
Visualize your filter design.
freqz([B,A]);
Filter Audio Using SOS Parametric Equalizer
Design a second-order sections (SOS) parametric equalizer using designParamEQ
and filter an audio stream.
Create audio file reader and audio device writer System objects. Use the sample rate of the reader as the sample rate of the writer.
frameSize = 256;
fileReader = dsp.AudioFileReader("RockGuitar-16-44p1-stereo-72secs.wav",SamplesPerFrame=frameSize);
sampleRate = fileReader.SampleRate;
deviceWriter = audioDeviceWriter(SampleRate=sampleRate);
Play the audio signal through your device.
count = 0; while count < 2500 audio = fileReader(); deviceWriter(audio); count = count + 1; end reset(fileReader)
Design an SOS parametric equalizer suitable for use with dsp.SOSFilter
.
N = [4,4];
gain = [-25,35];
centerFreq = [0.01,0.5];
bandwidth = [0.35,0.5];
[B,A] = designParamEQ(N,gain,centerFreq,bandwidth,Orientation="row");
Create an SOS filter.
myFilter = dsp.SOSFilter(B,A);
Create a spectrum analyzer to visualize the original audio signal and the audio signal passed through your parametric equalizer.
scope = spectrumAnalyzer( ... SampleRate=sampleRate, ... PlotAsTwoSidedSpectrum=false, ... FrequencyScale="log", ... Title="Original and Equalized Signals", ... ShowLegend=true, ... ChannelNames=["Original Signal","Equalized Signal"]);
Play the filtered audio signal and visualize the original and filtered spectrums.
count = 0; while count < 2500 originalSignal = fileReader(); equalizedSignal = myFilter(originalSignal); scope([originalSignal(:,1),equalizedSignal(:,1)]); deviceWriter(equalizedSignal); count = count + 1; end
As a best practice, release your objects once done.
release(deviceWriter) release(fileReader) release(scope)
Filter Audio Using FOS Parametric Equalizer
Design a fourth-order sections (FOS) parametric equalizer using designParamEQ
and filter an audio stream.
Construct audio file reader and audio device writer System objects. Use the sample rate of the reader as the sample rate of the writer.
frameSize = 256; fileReader = dsp.AudioFileReader( ... "RockGuitar-16-44p1-stereo-72secs.wav", ... SamplesPerFrame=frameSize); sampleRate = fileReader.SampleRate; deviceWriter = audioDeviceWriter( ... SampleRate=sampleRate);
Play the audio signal through your device.
count = 0; while count < 2500 x = fileReader(); deviceWriter(x); count = count + 1; end reset(fileReader)
Design FOS parametric equalizer coefficients.
N = [2,4]; gain = [5,10]; centerFreq = [0.025,0.65]; bandwidth = [0.025,0.35]; mode = "fos"; [B,A] = designParamEQ(N,gain,centerFreq,bandwidth,mode,Orientation="row");
Construct FOS IIR filters.
myFilter = dsp.FourthOrderSectionFilter(B,A);
Visualize the frequency response of your parametric equalizer.
freqz(myFilter)
Construct a spectrum analyzer to visualize the original audio signal and the audio signal passed through your parametric equalizer.
scope = spectrumAnalyzer( ... SampleRate=sampleRate, ... PlotAsTwoSidedSpectrum=false, ... FrequencyScale="log", ... Title="Original and Equalized Signals", ... ShowLegend=true, ... ChannelNames=["Original Signal","Equalized Signal"]);
Play the filtered audio signal and visualize the original and filtered spectra.
count = 0; while count < 2500 x = fileReader(); y = myFilter(x); scope([x(:,1),y(:,1)]); deviceWriter(y); count = count + 1; end
As a best practice, release your objects once done.
release(fileReader) release(deviceWriter) release(scope)
Input Arguments
N
— Filter order
scalar | row vector
Filter order, specified as a scalar or row vector the same length
as centerFreq
. Elements of the vector must be even
integers.
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
gain
— Peak gain (dB)
scalar | row vector
Peak gain in dB, specified as a scalar or row vector the same
length as centerFreq
. Elements of the vector must
be real-valued.
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
centerFreq
— Normalized center frequency of equalizer bands
scalar | row vector
Normalized center frequency of equalizer bands, specified as
a scalar or row vector of real values in the range 0 to 1, where 1
corresponds to the Nyquist frequency (π rad/sample). If centerFreq
is
specified as a row vector, separate equalizers are designed for each
element of centerFreq
.
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
bandwidth
— Normalized bandwidth
scalar | row vector
Normalized bandwidth, specified as a scalar or row vector the
same length as centerFreq
. Elements of the vector
are specified as real values in the range 0 to 1, where 1 corresponds
to the Nyquist frequency (π rad/sample).
Normalized bandwidth is measured at gain/2 dB.
If gain is set to -Inf
(notch filter), normalized
bandwidth is measured at the 3 dB attenuation point: .
To convert octave bandwidth to normalized bandwidth, calculate the associated Q-factor as
Then convert to bandwidth
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
mode
— Design mode
'sos'
(default) | 'fos'
Design mode, specified as 'sos'
or 'fos'
.
'sos'
–– Implements your equalizer as cascaded second-order filters.'fos'
–– Implements your equalizer as cascaded fourth-order filters. Because fourth-order sections do not require the computation of roots, they are generally more computationally efficient.
Data Types: char
| string
Name-Value Arguments
Specify optional pairs of arguments as
Name1=Value1,...,NameN=ValueN
, where Name
is
the argument name and Value
is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.
Before R2021a, use commas to separate each name and value, and enclose
Name
in quotes.
Example: 'Orientation',"row"
Orientation
— Orientation of returned filter coefficients
"column"
(default) | "row"
Orientation of returned filter coefficients, specified as the
comma-separated pair consisting of 'Orientation'
and
"column"
or "row"
.
Data Types: char
| string
Output Arguments
B
— Numerator filter coefficients
matrix
Numerator filter coefficients, returned as a matrix. The size and interpretation of
B
depends on the Orientation
and mode
:
If
'Orientation'
is set to"column"
andmode
is set to"sos"
, thenB
is returned as an L-by-3 matrix. Each column corresponds to the numerator coefficients of your cascaded second-order sections.If
'Orientation'
is set to"column"
andmode
is set to"fos"
, thenB
is returned as an L-by-5 matrix. Each column corresponds to the numerator coefficients of your cascaded fourth-order sections.If
'Orientation'
is set to"row"
andmode
is set to"sos"
, thenB
is returned as a 3-by-L matrix. Each row corresponds to the numerator coefficients of your cascaded second-order sections.If
'Orientation'
is set to"row"
andmode
is set to"fos"
, thenB
is returned as a 5-by-L matrix. Each row corresponds to the numerator coefficients of your cascaded fourth-order sections.
A
— Denominator filter coefficients
matrix
Denominator filter coefficients, returned as a matrix. The size and interpretation of
A
depends on the Orientation
and mode
:
If
'Orientation'
is set to"column"
andmode
is set to"sos"
, thenA
is returned as an L-by-2 matrix. Each column corresponds to the denominator coefficients of your cascaded second-order sections.A
does not include the leading unity coefficients.If
'Orientation'
is set to"column"
andmode
is set to"fos"
, thenA
is returned as an L-by-4 matrix. Each column corresponds to the denominator coefficients of your cascaded fourth-order sections.A
does not include the leading unity coefficients.If
'Orientation'
is set to"row"
andmode
is set to"sos"
, thenA
is returned as a 3-by-L matrix. Each row corresponds to the denominator coefficients of your cascaded second-order sections.If
'Orientation'
is set to"row"
andmode
is set to"fos"
, thenA
is returned as a 5-by-L matrix. Each row corresponds to the denominator coefficients of your cascaded fourth-order sections.
References
[1] Orfanidis, Sophocles J. "High-Order Digital Parametric Equalizer Design." Journal of the Audio Engineering Society. Vol. 53, November 2005, pp. 1026–1046.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
Introduced in R2016aR2024b: Warning that filter design functions will return coefficients in row orientation by default
The designVarSlopeFilter
, designParamEQ
, and designShelvingEQ
functions will
return filter coefficients in row orientation by default in a future release. With
row orientation, the functions return the coefficients as matrices where each row
contains the coefficients of the corresponding second-order section of the
filter.
The default value of the Orientation
name-value argument,
"column"
, will be removed in a future release and throws a
warning in R2024b. Set Orientation
to "row"
to return coefficients in row orientation in the current release.
R2024a: Filter design functions will return coefficients in row orientation by default
The designVarSlopeFilter
, designParamEQ
, and designShelvingEQ
functions will
return filter coefficients in row orientation by default in a future release.
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