Design Auditory Filter Bank

Design frequency-domain auditory filter bank

Since R2022a

• 

Libraries:
Audio Toolbox / Features

Description

The Design Auditory Filter Bank block outputs a frequency-domain auditory filter bank. You can use an auditory filter bank to decompose an audio signal into separate frequency bands for feature extraction.

Examples

Design Auditory Filter Bank

Design an auditory filter bank in Simulink.

• Open Model

Ports

Output

fb — Filter bank

column vector | matrix

Auditory filter bank, returned as an M-by-N matrix, where:

• M is the number of bands, which is determined by the Auto-determine number of bands and Number of bands parameters.

• N is the number of points in the spectrum. If you select Design one-sided filter bank, then N is equal to ceil(NFFT/2), where NFFT is the FFT length. If you do not select Design one-sided filter bank, then N is equal to the FFT length.

This port is unnamed until you select the Output center frequencies parameter.

Data Types: single | double

fvec — Center frequencies

row vector

Center frequencies of the bandpass filters in Hz, returned as a row vector with number of elements equal to the number of bands.

Dependencies

To enable this port, select the Output center frequencies parameter.

Data Types: single | double

Parameters

Frequency scale — Frequency scale of filter bank

mel (default) | bark | erb

Frequency scale used to design the auditory filter bank, specified as mel, bark, or erb.

• mel –– Design the filter bank as half-overlapped triangles equally spaced on the mel scale.

• bark –– Design the filter bank as half-overlapped triangles equally spaced on the Bark scale.

• erb –– Design the filter bank as gammatone filters whose center frequencies are equally spaced on the ERB scale.

Mel style — Mel style

oshaughnessy (default) | slaney

Style of the mel scale, specified as oshaughnessy or slaney.

Dependencies

To enable this parameter, set the Frequency scale parameter to mel.

FFT length — Number of DFT points

1024 (default) | positive integer

Number of points used to calculate the DFT, specified as a positive integer.

Design one-sided filter bank — Design one-sided or two-sided filter bank

on (default) | off

When you select this parameter, the block designs a one-sided filter bank. Otherwise, the filter bank is two sided.

Auto-determine number of bands — Automatically determine number of bandpass filters

on (default) | off

When you select this parameter, the block automatically determines the number of bandpass filters based on the Frequency scale parameter.

• If you set Frequency scale to mel or bark, then the number of bands is 32.

• If you set Frequency scale to erb, then the number of bands is equal to ceil(hz2erb(fr(2))-hz2erb(fr(1))), where fr is specified using Frequency range (Hz).

Number of bands — Number of bandpass filters

32 (default) | positive integer

Number of bandpass filters, specified as a positive integer.

Dependencies

To enable this parameter, clear the Auto-determine number of bands parameter.

Auto-determine frequency range — Automatically determine frequency range

on (default) | off

When you select this parameter, the block sets the Frequency range to [0,fs/2], where fs is specified using Sample rate (Hz).

Frequency range (Hz) — Frequency range over which to design auditory filter bank

[0,22050] (default) | two-element row vector

Frequency range in Hz over which to design the auditory filter bank, specified as a two-element row vector.

Dependencies

To enable this parameter, clear the Auto-determine frequency range parameter.

Filter bank design domain — Domain to design filter bank

linear (default) | warped

Domain in which the block designs the filter bank, specified as linear or warped. Set the filter bank design domain to linear to design the bandpass filters in the linear (Hz) domain. Set the filter bank design domain to warped to design the bandpass filters in the warped (mel or Bark) domain.

Dependencies

To enable this parameter, set Frequency scale to mel or bark.

Filter bank normalization — Normalization technique for filter bank

bandwidth (default) | area | none

Normalization technique used for the filter bank weights, specified as bandwidth, area, or none.

• bandwidth –– Normalize the weights of each bandpass filter by the corresponding bandwidth of the filter.

• area –– Normalize the weights of each bandpass filter by the corresponding area of the bandpass filter.

• none –– The block does not normalize the weights of the filters.

Output data type — Data type of output

double (default) | single

Data type of output, specified as double or single.

Sample rate (Hz) — Sample rate

44.1e3 (default) | positive scalar

Sample rate in Hz of the filter design, specified as a positive scalar.

Visualize filter bank — Open plot to visualize filter bank

button

Open plot to visualize the filters in the frequency domain.

Output center frequencies — Specify additional output port for center frequencies

off (default) | on

When you select this parameter, the block displays an additional output port, fvec. This port outputs the center frequencies of the bandpass filters.

Block Characteristics

Data Types	double | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2022a

R2023b: Support for Slaney-style mel scale

Set the Mel style parameter to slaney to use the Slaney-style mel scale.