Saturday, July 05, 2008

Using Equalization to Highlight Bird Calls

Posted by Philip Tyler



My goal was to capture early morning birds at a Reed Fen in the Titchwell RSPB Nature Reserve. Upon listening to the recording at home, the "roar" of the surf and the "rumble" of traffic on the coastal road seemed to interfere with the clarity of the bird sounds. Oddly enough, these sounds on the right channel (to the North) were louder than sounds from a village about the same distance to the left.


Using a narrow "Q" setting in the Parametric Equalization plug within Audition, I swept the frequency spectrum listening for bandwidths that seemed most obtrusive. I settled on moderate curves centered on three frequencies: 291 Hz, 862 Hz and 1770 Hz. I reduced the volume of these bandwidths 16 dB, 15 dB and 20 dB respectively. At 291 Hz there was an objectionable rumble. At 862 Hz there was a pronounced roar from the road and surf and there was excessive airyness around 1770 Hz.

I sent the original recording to Rob Danielson to see how he might handle the task of making the bird calls more apparent. He equalized the recording to his tastes and produced a QuickTime video comparing my EQ settings with the original recording, his EQ settings with the original recording and our EQ settings against each other.
Our results sound quite similar! I used only low frequency "cut" while Rob used a combination of attenuating low frequencies and boosting high ones. Rob also equalized the right channel differently to try to compensate for the heavier bass on the right side. The down side of the EQ that we used was lowered presence of the Collared Doves and Wood Pigeon whose calls were affected by the low frequency attenuation. I am pretty happy with the results and having Rob come-up with similar results is assuring. I'm convinced that if one is willing to spend time experimenting with EQ, you can get quite acceptable results.


My microphone rig was comprised of two "shotgun" Sennheiser ME66 mics in a crossed configuration angled about 25 degrees. The mics were powered and amplified by a Sound Devices MixPre and recorded on a Sony MZRH1 Hi-MD.


7 Comments:

At 4:18 AM, Blogger catlee said...

Hi there,

I'm interested in reading that you use 2 me66 mics for your stereo recording?

I was planning to make a binaural rig for two me66 mics, for some rain recordings I've been commissioned to do, but I haven't found much evidence of people using the me66's in this way.

Do you use them for this purpose or just as a stereo pair. Can you offer any pros and cons of using the me66's in a stereo pairing.

I already have one me66 and was planning to purchase another one, or perhaps a pair of in-ear binarual mics, but I'm conscious of the sound quality and noise levels.

I do a lot of wildlife recording in my personal work, so am searching for an accurate and emotive stereo picture. If you had any advice that would be much appreciated.

All the best

Cat

 
At 7:45 AM, Blogger Rob D. said...

Hi Cat--
As I'm sure you are aware, making a binaural rig with two directional, "shotgun" mics isn't typical. Nearly all, if not all, binaural rigs use omni-directional mics.

Rain is a fairly robust sound source so mic self-noise is not going to be a huge issue. I'd consider making a DIY binaural rig with one of the small, electret mic capsules. Search "DIY electret mics."

Unfortunately, there are no, small, very low self-noise omni mics for recording things like ambience in "quiet," natural settings. Some hiss and noise masking is unavoidable unless you go with larger condenser mics with very low self-noise.

If a small profile is important and you're on a budget, about the best you can do is the Shure wl183. "A search of "wl 183 nature" should lead you to things folks are doing with these mics.

If you are interested in stereo options, I would not start with getting another ME-66 and starting there. Rob D.

 
At 4:20 PM, Blogger catlee said...

Hi Rob,

Goodness me, thanks for the advice. Glad I got in touch. I was really on the wrong track.

I would prefer something with low self noise, but also have a fairly limited budget.

Having looked into the areas you suggested I've decided to follow either the wl183 path or buy a set of these,

http://www.core-sound.com/mics.html

I'm not sure if you know anything about them, I'm presuming they are and adaptation of or something similar to the WM-61A's ?

Thanks again for your advice, I'm truly grateful that you saved me from a costly mistake. If you have any further advice it would be much appreciated, but not expected.

Thanks again.

All the best

Cat

 
At 8:39 AM, Blogger Rob D. said...

Hi Cat--
Glad I could be of help. You are correct that quite a few companies repackage Panasonic and other small electret capsules and mark them up. I tried to get a handle on the options for a friend who wasn't keen on soldering by starting this list: https://pantherfile.uwm.edu/type/public/temporary/._CompareCommercialLavs_1_2009.doc or try http://tinyurl.com/c6ubdu if that download link doesn't work. The only commercially available mics I know of which have comparable (still, only "okay,") self-noise performance to that of the Shure WL183's are the DPA's 4060's which are on the .doc list. If you download it as a ".doc" it should have links. Rob D.

 
At 4:24 PM, Blogger Cat Lee Marr said...

Hi Rob,

It is such a long time since I bought the wl 183's , I hope you are still reading this page. I attached them to a stereo 1/4 inch jack but now I want to separate them into individual 3pin xlr jacks - I can't find the original diagram I had for doing this? Any ideas? Any help would be much apreciated x

 
At 4:56 PM, Blogger Rob D. said...

catlee--
Do you want to hook the original mini XLR plugs back-up-- just like they were before you cut them off? ? What recorder do you wan to connect them to?? Rob D.

 
At 6:16 AM, Blogger pters said...

So why did you use a pair of ME66s?

 

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