Octaveband and fractional octaveband filter
Audio Toolbox / Filters
The Octave Filter block performs octaveband or fractional octaveband filtering independently across each input channel. An octaveband is a frequency band where the highest frequency is twice the lowest frequency. Octaveband and fractional octaveband filters are commonly used to mimic how humans perceive loudness. Octave filters are best understood when viewed on a logarithmic scale, which models how the human ear weights the spectrum.
Data Types 

Direct Feedthrough 

Multidimensional Signals 

VariableSize Signals 

ZeroCrossing Detection 

[1]
, Sophocles J. Introduction to Signal Processing. Englewood Cliffs, NJ: Prentice Hall, 2010.[2] Acoustical Society of America. American National Standard Specification for OctaveBand and FractionalOctaveBand Analog and Digital Filters: ANSI S1.112004. Melville, NY: Acoustical Society of America, 2009.