Scale--bark scale and Mel scale in audio processing

Source: Internet
Author: User

Because the human ear to the sound perception (such as: frequency, tone) is non-linear, in order to measure the perception of the sound, produced a series of scales (such as: 12 Average law), here the emphasis on bark scale and Mel scale. At first, I didn't understand the difference between the two scales myself. Then gradually understand their starting point of thinking, here simply share it.

Bark (buck) Frequency scale is in Hz, the frequency mapping to the psychological acoustics of the 24 critical frequency band, the 25th critical frequency band occupy about: 16k~20khz frequency, 1 critical frequency band width equals a Bark, simply said, Bark scale is to convert the physical frequency to the frequency of psychological acoustics. The central frequency and the critical bandwidth boundary frequency of the bark scale frequency are shown in the following table:

Critical band Frequency/hz
Bark Band Center frequency Nether Frequency Upper bound frequency
1 50 0 100
2 150 100 200
3 250 200 300
4 350 300 400
5 450 400 510
6 570 510 630
7 700 630 770
8 840 770 920
9 1000 920 1080
10 1170 1080 1270
11 1370 1270 1480
12 1600 1480 1720
13 1850 1720 2000
14 2150 2000 2320
15 2500 2320 2700
16 2900 2700 3150
17 3400 3150 3700
18 4000 3700 4400
19 4800 4400 5300
20 5800 5300 6400
21st 7000 6400 7700
22 8500 7700 9500
23 10500 9500 12000
24 13500 12000 15500
25 18775 15500 22050

I've found that there are a number of formulas that try to model the above table, using a much more of the formula (Zwicker,terhardt 1980):

\[b = 13{\tan ^{-1}}\left ({\frac{{0.76f}}{{1000}}} \right) + 3.5{\tan ^{-1}}{\left ({\frac{f}{{7500}} \right) ^2}\]

The above-mentioned frequency F represents the center frequency, I put the above formula in MATLAB to calculate, found the first 5 bark band and the calculation of the entrance is relatively large, do not know what the reason.

The Mel frequency scale is also a frequency-mapping-aware model that describes the nonlinear mapping of pitch-aware functions, which are represented as follows:

\[m = 1127.01048{\log _e}\left ({1 + \frac{f}{{700}}} \right) \]

One thing to note is that the frequency F unit here is 1kHz, that is, 1kHz is the reference point between the Mel frequency and the true frequency in Hertz (1khz=1000mel), on the other hand, Mel is derived from the music terminology melody, Is the measure of the distance between the frequency component of the melody and the pitch perception.

This article is from Icoolmedia, the related algorithm exchange please go to the audio and video algorithm discussion group (374737122) to communicate together!

Scale--bark scale and Mel scale in audio processing

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