# getCenterFrequencies

Center frequencies of filters

## Syntax

``cf = getCenterFrequencies(obj)``

## Description

example

````cf = getCenterFrequencies(obj)` returns the center frequencies of the filters created by `obj`, in Hz.```

## Examples

collapse all

Create a `gammatoneFilterBank` and get the center frequencies of the filters in the filter bank.

```gammaFiltBank = gammatoneFilterBank; cf = getCenterFrequencies(gammaFiltBank)```
```cf = 1×32 103 × 0.0500 0.0822 0.1181 0.1581 0.2027 0.2525 0.3081 0.3700 0.4391 0.5162 0.6022 0.6980 0.8050 0.9242 1.0573 1.2056 1.3711 1.5557 1.7616 1.9912 2.2473 2.5329 2.8515 3.2069 3.6032 4.0453 4.5384 5.0883 5.7017 6.3858 7.1489 8.0000 ```

Center frequencies of a gammatone filter bank are spaced evenly on the ERB scale. Convert the center frequencies vector to the ERB scale and calculate the differences between center frequencies.

`diff(hz2erb(cf))`
```ans = 1×31 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 1.0130 ```

Create an `octaveFilterBank` and get the center frequencies of the filters in the filter bank.

```octFiltBank = octaveFilterBank; cf = getCenterFrequencies(octFiltBank)```
```cf = 1×10 104 × 0.0032 0.0063 0.0126 0.0251 0.0501 0.1000 0.1995 0.3981 0.7943 1.5849 ```

Center frequencies of an octave filter bank are spaced evenly on a logarithmic scale. Convert the center frequencies vector to the log scale and calculate the differences between center frequencies.

`diff(log10(cf))`
```ans = 1×9 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 ```

Create an octave bandwidth `splMeter` and get the center frequencies of the octave filter bank. Round the center frequencies to two significant digits for display purposes.

```SPL = splMeter('SampleRate',44100,'Bandwidth','1 octave'); cf = getCenterFrequencies(SPL); round(cf,2,'significant')```
```ans = 1×10 32 63 130 250 500 1000 2000 4000 7900 16000 ```

## Input Arguments

collapse all

Object to get filter bank center frequencies from, specified as an object of `gammatoneFilterBank`, `octaveFilterBank`, or `splMeter`.

## Output Arguments

collapse all

Filter bank center frequencies in Hz, returned a scalar or vector. 