On Apr 12, 7:00�am, Nadav <nadav...@gmail.com> wrote:
> I am executing MFCC with 100msec sliding window on a 10Khz feed, I
> would like to measure the energy for each Mel Frequency Filter, sounds
> trivial so far, I would expect the follwoing to give me exactly that:
>
> 1. A sliding window in time of e.g. 100msec
> 2. Applying a window function ( e.g. Hamming ) to reduce leakage
> 3. executing FFT
> 4. Applying Mel, Bark ( or whatever ) Frequency Filter bank
> 5. Log coefficients for the Filter Bank ~buckets~
> (*) Having the above applied the bucket of the highest energy should
> have the highest Log coeeficient.
>
> To verify this, I have synthisized a 2400Hz signal and extracted the
> features using the above mentioned flow, I have expected the ~6th
> filter to have the highest coefficient value, suprisingly, the 1st
> coefficient ( 0 - 1KHz ) had the highest value, WHY ? ( I assume this
> is somehow related with the fact that the FFT is executed on a 100msec
> window while the result is projected on a freq larger than the Nyquist
> frequency ).
>
> Can I accurately derive the energy at a specific frequecy using MFCC
> features ?
>
> Any help would be appreciated.
If I understand your post correctly, ask yourself what is in the first
bin (0 - 1KHz) of your FFT.
Reply by Nadav●April 12, 20112011-04-12
I am executing MFCC with 100msec sliding window on a 10Khz feed, I
would like to measure the energy for each Mel Frequency Filter, sounds
trivial so far, I would expect the follwoing to give me exactly that:
1. A sliding window in time of e.g. 100msec
2. Applying a window function ( e.g. Hamming ) to reduce leakage
3. executing FFT
4. Applying Mel, Bark ( or whatever ) Frequency Filter bank
5. Log coefficients for the Filter Bank ~buckets~
(*) Having the above applied the bucket of the highest energy should
have the highest Log coeeficient.
To verify this, I have synthisized a 2400Hz signal and extracted the
features using the above mentioned flow, I have expected the ~6th
filter to have the highest coefficient value, suprisingly, the 1st
coefficient ( 0 - 1KHz ) had the highest value, WHY ? ( I assume this
is somehow related with the fact that the FFT is executed on a 100msec
window while the result is projected on a freq larger than the Nyquist
frequency ).
Can I accurately derive the energy at a specific frequecy using MFCC
features ?
Any help would be appreciated.