Tuesday, 3 January 2017

Removing the sounds you don't want

Most of your recordings will feature some sound that you don’t want to keep, and there are several ways to get rid of them.  Some will be sounds you want to eliminate completely. You’ll record dogs barking, people talking, the cable hitting the mic, the clicks caused by a loose connection, and any number of other bits of unwanted noise. You can literally cut these out of your recordings with Audacity. 

At the beginning of this recording of a great tit, you’ll see some broadband (i.e. covering almost all frequencies) sound I made while rummaging around with the mic. I nearly always capture some of this noise as I have my recorder set to record sounds from 2 seconds before I actually press the button. It's set up like this to give me a better chance of getting flyovers or birds that only call once. 

To remove this, highlight the unwanted area by right clicking on the screen and dragging to highlight the area you want to remove. Then, click on the scissors icon - and your unwanted section will be removed. Note that you can only do this across all frequencies - i.e. you can’t highlight within a specific frequency range, only across a specific time period. 

The edited sonogram looks like this

Keep in mind that you’re removing some time from your recording, so the gaps between calls or song phrases will be reduced. If this needs to be addressed, you can simply copy an area from your recording of a similar length, and paste it into the right place. In my recording I’ve selected a section containing a ticking robin to maintain roughly the right period between the great tit phrases. To copy, simply select the area you want to copy in the same way you selected the section to remove. When the required area is highlighted, choose COPY from the edit menu (top of the screen). Then you just need to click where you want to insert the copied section, return to the edit menu, and hit PASTE.

EDIT - the good people at Xeno-Canto have been in touch and suggested that inserting noise from elsewhere in your recording might not be such a good idea - and have recommended adding in a silent section of the correct length instead.

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