<p>That's a tricky one... Is this noise somewhat constant? If so, I guess you could substract a portion of the recording without bird calls to a bird call portion.
If it is not constant or if at all possible, the best solution would be to redo your recordings with a recorder and microphone that does not have electrical noise.</p>

CC BY-SA 4.0
2022-07-01T09:50:36.787Z
2022-07-01T09:50:36.787Z
Cam Desjonqu
<p>I assume that the noise lines are really clipped tonal.</p>
<p>one way of reconstructing the signal is to use an interpolating fft (fft length &gt; window length) so that tonals are limited to a few frequency bins. Then replace amplitude and phase by, say a linear interpolation of the adjacent (good) frequency bins. on return to time domain you should have a good approximation to the clean signal.</p>
<p>Edit: If you take a time bin of a (complex) spectrogram or output of FFT, then you will see the multi-harmonic lines peaking up very sharply, replacing completely the spectral information of your signal. If your signal is visible at lower and higher frequencies, then the noise, you could simply mask your interferences. this would correspond to a notch filter. you can also replace the interferences with a value that is between the upper and lower frequency bin. You do this either for amplitude and (unwraped) phase or for real and imaginary of the complex spectrum. This will not reconstruct the true signal spectrum but is the best you can do.</p>

CC BY-SA 4.0
2022-07-03T07:13:53.153Z
what is meant here by 'replace amplitude and phase' - of the noise? Could you please explain the answer in a bit more detail?
Thejasvi
CC BY-SA 4.0
2022-07-01T16:03:35.380Z
2022-07-03T08:36:45.323Z
2022-07-03T08:36:45.323Z
WMXZ
<p>My recordings of bird calls have multi-harmonic noise (probably generated by some electronic device e.g. as mentioned <a href="https://bioacoustics.stackexchange.com/q/93/131">here</a>). I would like to perform peak-frequency and other such spectral measurements.</p>
<p>The multi-harmonic noise is continuous and overlaps all of my bird calls, which means any measurements will have the noise component in it. How can I 'subtract' the noise to get the true spectral measurements of the bird call itself?</p>

CC BY-SA 4.0
2022-07-02T00:45:09.310Z
Could you provide an example spectrogram image so we can more easily understand the structure of the noise?
Taiki Sakai
CC BY-SA 4.0
2022-07-02T18:24:04.643Z
This is an 'anticipatory' question - don't have any spectrograms at hand :| .
Thejasvi
CC BY-SA 4.0
2022-07-03T13:56:48.137Z
How much audio manipulation experience do you have? Filters can do a lot, but it's possible you need different filters for different kinds of analysis since the filters will influence the data. This could get cumbersome really fast.
Mast
<recording><experiment-design><noise>
I have electronic noise in my bird call recordings. How do I account for this noise while performing measurements?
# I have electronic noise in my bird call recordings. How do I account for this noise while performing measurements?

(Asked by: username_0 on 2022-07-01)

My recordings of bird calls have multi-harmonic noise (probably generated by some electronic device e.g. as mentioned [here](https://bioacoustics.stackexchange.com/q/93/131)). I would like to perform peak-frequency and other such spectral measurements.

The multi-harmonic noise is continuous and overlaps all of my bird calls, which means any measurements will have the noise component in it. How can I 'subtract' the noise to get the true spectral measurements of the bird call itself?

**Tags:** recording, experiment-design, noise

> **Comments:**
> **username_1**: Could you provide an example spectrogram image so we can more easily understand the structure of the noise?  
> **username_0**: This is an 'anticipatory' question - don't have any spectrograms at hand :| .  
> **username_2**: How much audio manipulation experience do you have? Filters can do a lot, but it's possible you need different filters for different kinds of analysis since the filters will influence the data. This could get cumbersome really fast.  

---

## 2 answers

### Answer by username_4 on 2022-07-01. Score: 8 | Accepted answer

I assume that the noise lines are really clipped tonal.

one way of reconstructing the signal is to use an interpolating fft (fft length > window length) so that tonals are limited to a few frequency bins. Then replace amplitude and phase by, say a linear interpolation of the adjacent (good) frequency bins. on return to time domain you should have a good approximation to the clean signal.

Edit: If you take a time bin of a (complex) spectrogram or output of FFT, then you will see the multi-harmonic lines peaking up very sharply, replacing completely the spectral information of your signal. If your signal is visible at lower and higher frequencies, then the noise, you could simply mask your interferences. this would correspond to a notch filter. you can also replace the interferences with a value that is between the upper and lower frequency bin. You do this either for amplitude and (unwraped) phase or for real and imaginary of the complex spectrum. This will not reconstruct the true signal spectrum but is the best you can do.

> **Comments:**
> **username_0**: what is meant here by 'replace amplitude and phase' - of the noise? Could you please explain the answer in a bit more detail?  

---

### Answer by username_3 on 2022-07-01. Score: 2

That's a tricky one... Is this noise somewhat constant? If so, I guess you could substract a portion of the recording without bird calls to a bird call portion.
If it is not constant or if at all possible, the best solution would be to redo your recordings with a recorder and microphone that does not have electrical noise.


---

