<p>There are two broad approaches. The first is to make a simplifying assumptions that the sweep is best modelled as its peak frequency. Especially if the peak frequency is kind of in the 'middle' of the highest and lowest frequencies, this assumption is likely to yield decent results.</p>
<p>The second approach actually considers all frequencies in the sound. Here there are two methods 1) use a custom-designed finite-impulse response filter and convolve it with the call's waveform. 2) calculate the amount of atmospheric absorption expected due to distance from microphone at each frequency and 'add'(in the dB scale) this to the power spectrum. You can then calculate the RMS of the call using <a href="https://en.m.wikipedia.org/wiki/Parseval%27s_theorem" rel="nofollow noreferrer">Parseval's equivalence</a> or get back the waveform through an inverse FFT.</p>
<p>With either approach it is important that your recording is 'clean'. If there is a lot of reverberation or noise in the audio, all of this too will be amplified when atmospheric attenuation is compensated!</p>

CC BY-SA 4.0
2022-06-24T13:16:37.500Z
2022-06-25T08:15:33.723Z
2022-06-25T08:15:33.723Z
Thejasvi
<p>I have bat call recordings from a microphone array, meaning i also know the 3d coordinates at which the calls were emitted.</p>
<p>The 3d coordinates allows me to compensate for spherical spreading. I know how to compensate for atmospheric attenuation for a single frequency sound. However, bat calls are broadband frequency modulated sweeps - how do I compensate for the differential atmospheric attenuation across multiple frequencies?</p>

<loudness><localisation><attenuation>
How to compensate for atmospheric attenuation of a broadband sound?
# How to compensate for atmospheric attenuation of a broadband sound?

(Asked by: username_0 on 2022-06-24)

I have bat call recordings from a microphone array, meaning i also know the 3d coordinates at which the calls were emitted.

The 3d coordinates allows me to compensate for spherical spreading. I know how to compensate for atmospheric attenuation for a single frequency sound. However, bat calls are broadband frequency modulated sweeps - how do I compensate for the differential atmospheric attenuation across multiple frequencies?

**Tags:** loudness, localisation, attenuation


---

## 1 answers

### Answer by username_0 on 2022-06-24. Score: 3 | Accepted answer

There are two broad approaches. The first is to make a simplifying assumptions that the sweep is best modelled as its peak frequency. Especially if the peak frequency is kind of in the 'middle' of the highest and lowest frequencies, this assumption is likely to yield decent results.

The second approach actually considers all frequencies in the sound. Here there are two methods 1) use a custom-designed finite-impulse response filter and convolve it with the call's waveform. 2) calculate the amount of atmospheric absorption expected due to distance from microphone at each frequency and 'add'(in the dB scale) this to the power spectrum. You can then calculate the RMS of the call using [Parseval's equivalence](https://en.m.wikipedia.org/wiki/Parseval%27s_theorem) or get back the waveform through an inverse FFT.

With either approach it is important that your recording is 'clean'. If there is a lot of reverberation or noise in the audio, all of this too will be amplified when atmospheric attenuation is compensated!


---

