hz2mel

Convert from hertz to mel scale

Syntax

mel = hz2mel(hz)

mel = hz2mel(hz,MelStyle=style)

Description

mel = hz2mel(hz) converts values in hertz to values on the mel frequency scale.

mel = hz2mel(hz,MelStyle=style) specifies whether to use the Slaney-style or O'Shaughnessy-style mel scale.

Examples

Convert Between Mel Scale and Hz

Set two bounding frequencies in Hz and then convert them to the mel scale.

b = hz2mel([20,8000]);

Generate a row vector of 32 values uniformly spaced on the mel scale.

melVect = linspace(b(1),b(2),32);

Convert the row vector of values into equivalent frequencies in Hz.

hzVect = mel2hz(melVect);

Plot the two vectors for comparison. As mel values increase linearly, Hz values increase exponentially.

plot(melVect,hzVect,'o')
title('Mel vs Hz')
xlabel('Mel')
ylabel('Hz')
grid on

Compare O'Shaughnessy-Style and Slaney-Style Mel Scale

Create a vector containing frequencies from 0 Hz to 8000 Hz.

hz = 0:8e3;

Convert the frequencies to the mel scale. By default, hz2mel uses the O'Shaughnessy-style mel scale.

mel_oshaughnessy = hz2mel(hz);

Convert the frequencies using the Slaney-style mel scale by calling hz2mel with MelStyle set to "slaney".

mel_slaney = hz2mel(hz,MelStyle="slaney");

Plot both the O'Shaughnessy-style and Slaney-style mel frequencies against the frequency in Hz.

plot(hz,mel_oshaughnessy)
ylabel("Mel (O'Shaughnessy)")
yyaxis right
plot(hz,mel_slaney)
ylabel("Mel (Slaney)")
xlabel("Hertz")

Input Arguments

hz — Input frequency in Hz

scalar | vector | matrix | multidimensional array

Input frequency in Hz, specified as a scalar, vector, matrix, or multidimensional array.

Data Types: single | double

style — Mel style

"oshaughnessy" (default) | "slaney"

Mel style, specified as "oshaughnessy" or "slaney".

Data Types: char | string

Output Arguments

mel — Output frequency on mel scale

scalar | vector | matrix | multidimensional array

Output frequency on the mel scale, returned as a scalar, vector, matrix, or multidimensional array the same size as hz.

Data Types: single | double

Algorithms

The frequency conversion from Hz to the O'Shaughnessy-style mel scale uses the following formula [1]:

$$mel=2595{\log }_{10}\left(1+\frac{hz}{700}\right)$$

The Slaney-style mel scale follows [2]. The scale is linear with respect to Hz below 1000 Hz, and it is logarithmic above 1000 Hz.

References

[1] O'Shaughnessy, Douglas. Speech Communication: Human and Machine. Reading, MA: Addison-Wesley Publishing Company, 1987.

[2] Slaney, Malcolm. "Auditory Toolbox: A MATLAB Toolbox for Auditory Modeling Work." Technical Report, Version 2, Interval Research Corporation, 1998.

Extended Capabilities

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

Version History

Introduced in R2019a

R2023b: Support for Slaney-style mel scale

Set the MelStyle name-value argument to "slaney" to use the Slaney-style mel scale.