getANSICenterFrequencies

Get the list of valid ANSI S1.11-2004 center frequencies

Syntax

``centerFrequencies = getANSICenterFrequencies(octFilt)``

Description

example

````centerFrequencies = getANSICenterFrequencies(octFilt)` returns a vector of valid center frequencies as specified by the ANSI S1.11-2004 standard.```

Examples

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Create an object of the `octaveFilter` System object™. Call `getANSICenterFrequencies` to get a list of valid center frequencies.

```octFilt = octaveFilter; centerFrequencies = getANSICenterFrequencies(octFilt)```
```centerFrequencies = 1×15 103 × 0.0005 0.0010 0.0020 0.0040 0.0079 0.0158 0.0316 0.0631 0.1259 0.2512 0.5012 1.0000 1.9953 3.9811 7.9433 ```

Input Arguments

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Object of the `octaveFilter` System object™.

Output Arguments

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Center frequencies specified by the ANSI S1.11-2004 standard, returned as a vector.

The range for computing valid center frequencies is 3 Hz to (Fs/2) Hz, where the `SampleRate` property of your octave filter defines Fs.

Data Types: `single` | `double`

Algorithms

The ANSI S1.11-2004 standard [1] defines the center frequencies of the octave bands as

where:

• fr is the reference frequency, 1000 Hz.

• G is the octave ratio, 100.3.

• b is the number of bands per octave, which is the inverse of the bandwidth of the filter in octaves. Specify the bandwidth using the Bandwidth property of `octFilt`.

• k is any integer and represents the band number.

The center frequency definition differs depending on whether b is odd, such as for bandwidths of 1 octave or 1/3 octave, or even, such as for bandwidths of 1/2 octave or 1/6 octave. This ensures that the band edges of the whole octave band remain band edges for all of the fractional bands.

References

[1] Acoustical Society of America. American National Standard Specification for Octave-Band and Fractional-Octave-Band Analog and Digital Filters. ANSI S1.11-2004. Melville, NY: Acoustical Society of America, 2009.

Version History

Introduced in R2016b