The first one sounds like a distant car door to me. Though it could be som=
In any case I think the quickest way to spot them without listening to the =
whole recording is to look at the recording spectrogram and the very low fr=
equency energy will show up strongly at the bottom of the frequency spectru=
m. The free software Audicity has a spectrogram mode that is pretty good.
After that you could use software such as Izotope RX Spectral Repair to rep=
air the noises. I have had success with these types of sounds in the past =
using Spectral Repair. It can erase them with no audible artifacts if you =
use it right.
--- In Peter Shute <> wrote:
> Well, that was smart. I forgot to include the link to a sample of the rec=
> I've put comments where all the thumps are in that one minute sample.
> Peter Shute
> From: =
On Behalf Of Peter Shute
> Sent: Tuesday, 6 November 2012 5:52 AM
> Subject: [Nature Recordists] Background thumps in recording
> I recentlly made some recordings in Murray Sunset National Park, in north=
west Victoria, Australia. It was, I thought, a very quiet place in the mor=
nings before the wind started, apart from the birds.
> But in one recording, there is a thumping noise at random intervals, righ=
t through the two hour recording, which starts just before sunrise. Could I=
please have some opinions on what these noises might be?
> At first I thought they were a car door being slammed - we were camped ab=
out 300m away, just over the hill - but there are far too many of them. Gun=
shots? Not allowed in the park, and the nearest farms are over 10km away, a=
lthough it's still possible, as there are feral goats in the park.
> I'd also like to know if there's a good way of finding all of these in th=
e recording without having to listen to it. I can only hear them if I use h=
eadphones, and if there's no background noise in the room, so it took me a =
while to find as many as I have.
> After I'd found a few just by listening, I used EQ to reduce everything a=
bove 400Hz and increase everything below 200Hz. This makes them way more ob=
vious to the ear, and I can spot most on the waveform, but it's not very pl=
easant to listen to. It also makes the sound of wingbeats sound similar, so=
I made a few mistakes.
> Could there be an automated way of finding them all, or making them relia=
bly more obvious on the waveform? I use Audacity.
> Peter Shute