How do you calculate the difference in noise between two audio signals?

Hi

I have two signals that are created from audio files using the audioread function.

The first is the original signal. The second has information I have hidden in it using steganography.

I'd like a way of quantifying the differnce other than just listening or plotting the sounds.

I think this should be a measure of noise - but the difference between the two?

Suggestions or help very welcome!

[Paul Hoffrichter]

>> This is a completely different approach than the one I was considering

Not sure I understand what you are looking for. Could you elaborate on what you were considering?

The hidden signal is not noise. You and the recipient know everything needed to reconstruct the hidden signal.

E.g., One simple approach: New Signal = Music signal + hidden signal.

To recover this,

hidden signal = Signal - Music signal (known to recipient).

What metric are you looking for - SNR? https://www.mathworks.com/help/signal/ref/snr.html

Answer 1

[Rishabh Mishra]

Hi,

I am assuming that the original audio signal is named ‘org’ & the modified (through steganography) audio signal is named ‘mod’.

Now, it is to be understood that noise is not a characteristic (like frequency, amplitude etc.) of sound (or in this case, audio signal), so it is not possible for any kind of software or electronic tool to straightaway extract noise from an audio signal unlike amplitude, frequency etc.

However, we can apply various filtering techniques to an audio signal. Say, after applying filtering to ‘org’ & ‘mod’, the filtered signals obtained are ‘filter_org’ & ‘filter_mod’. You can remove the filtered components from original audio signals, what you are left with is the noise itself, use these noise audio signals to serve your purpose.

Disclaimer: every filtering technique may give slightly different kind of filtered audio signal & therefore, noise obtained from each of the filter will be different.

To know more about noise filtering in MATLAB, refer the following links:

1. How to pass a audio signal through a filter
2. extract noise and apply it at other data
3. how to separate noise from signal
4. how to extract noise amplitude from a signal

[Anthony Phipps]

Thank you

This is a completely different approach than the one I was considering and I will try these

Cheers!