# audspec: Frequency band conversion In tuneR: Analysis of music and speech

## Description

Perform critical band analysis (see PLP), which means the reduction of the fourier frequencies of a signal's powerspectrum to a reduced number of frequency bands in an auditory frequency scale.

## Usage

 ```1 2 3``` ```audspec(pspectrum, sr = 16000, nfilts = ceiling(hz2bark(sr/2)) + 1, fbtype = c("bark", "mel", "htkmel", "fcmel"), minfreq = 0, maxfreq = sr/2, sumpower = TRUE, bwidth = 1) ```

## Arguments

 `pspectrum` Output of `powspec`, matrix with the powerspectrum of each time frame in its columns. `sr` Sample rate of the original recording. `nfilts` Number of filters/frequency bins in the auditory frequency scale. `fbtype` Used auditory frequency scale. `minfreq` Lowest frequency. `maxfreq` Highest frequency. `sumpower` If `sumpower = TRUE`, the frequency scale transformation is based on the powerspectrum, if `sumpower = FALSE`, it is based on its squareroot (absolute value of the spectrum) and squared afterwards. `bwidth` Modify the width of the frequency bands.

## Value

 `aspectrum ` Matrix with the auditory spectrum of each time frame in its columns. `wts ` Weight matrix for the frequency band conversion.

## Author(s)

Sebastian Krey [email protected]

## References

Daniel P. W. Ellis: http://www.ee.columbia.edu/~dpwe/resources/matlab/rastamat/

`fft2melmx`, `fft2barkmx`
 ```1 2 3``` ``` testsound <- normalize(sine(400) + sine(1000) + square(250), "16") pspectrum <- powspec(testsound@left, testsound@samp.rate) aspectrum <- audspec(pspectrum, testsound@samp.rate) ```