Posted by: recordingsofnature | April 24, 2016

Sunny April morning by Sømosen

This is a sound recording and photo capture from a sunny and windy April morning (22.4.2016) by Sømosen, where I have been recording a few times before. Fairly cold winds were blowing from North west. However, in the shelter of a row of bushes and trees, the sun felt incredibly nice. Many were out for a walk or walking the dog this morning.

April 22, 2016 Sømosen, Ballerup. Microphone setup

Spring is slightly late this year, as compared to last year. Still not that many singing birds, but chiffchaff and robin are surely active. About 200 meters ahead you can hear noise from the bog, mainly from a colony of black headed gulls and greylag gees just appearing with crowds of young gosling. This sound is however quite faint due to the wind direction coming from the opposite direction.

The audio recording is intended to be as authentic as possible, with minimum post processing. Listen in headphones.

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This is an update on the CYL-filter method for anti-aliasing of DSLR video, and a description of how to get a filter which has a variable anti-aliasing filter strength. The method is to simply use two filters in a stack, and by adjusting the rotation it is possible to vary the filter effect from zero to the double amount. Almost like a variable ND filter.

In this article I will sum up the developments, and give a demonstration of a prototype filter. Unfortunately, I am not able to do any manufacturing or selling. Instead, I will try to give all details to make way for trying it DIY.

Variable anti-aliasing filter (CYL-filter) for digital DSLR video

The original CYL-filter method has limitations in terms of a strict working range with a narrow set of working points with respect to aperture and lens focal length. A very strong filter is normally needed for wide angle lenses, while a very weak filter is needed for long lenses. Add to this the dependency of the aperture size. So, a variable solution is really an advantage and extends the working range.

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Posted by: recordingsofnature | April 2, 2016

Road noise and the influence of Weather factors

Deep rumbling road noise is a true companion on my nature recording trips around in Denmark. Maybe it is due to modern headphones or to bass sensitive microphones – the rumbling is just ever present when I get home and hear the recordings. Noise from cross-cutting motorways can be particularly audible over long distances, however the noise level do vary surprisingly from time to time at the same location.

I have started to realize that weather conditions play a major role for this ambient background noise. The typically far distant nature of these sounds gives a high sensitivity to weather conditions. The atmosphere plays an active role in reflecting and guiding long distance sounds. It is actually a well-founded but highly complex research field. Sound differences of 10-20dB are often stated.


To my experience, road noise (closely followed by aircraft noise) is the most common and persistent type of noise encountered on my field recordings. Other man made noise types include trains, industrial activities, shooting ranges, lawn cutters, dogs and …wind turbines. I definitely don’t see this as all bad. The background ambience is very important for the identity of a place, often at a subconscious level. Imagine 100 years ago how completely different the ambience must have been, and again in 100 years time it will likely be completely different, e.g. with the emergence of electric cars and climate changes etc.

All in all, I have come to see that studying weather forecasts and road maps can be very instrumental when planning audio nature recordings. Considering weather factors is, in general, a great help to understand the often surprising outcomes of audio field recordings. In this blog I will try to dig more into this topic and compile various related information.


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Posted by: recordingsofnature | March 8, 2016

Sound of rainy forest – early March 2016

This is an audio field recording of an early, rainy and cold Sunday morning in Brøndbyskoven, March 6th 2015. The clip starts just after sunrise, the temperature is about 2C.
This is the time of the year – that I kind of like – just before the onset of spring. It is getting much lighter but still so cold that the birds are only in the mood for subtle and halfhearted calls. In a month or two everything will be much more hectic and fullblown.

IMG_6476 - IMG_6477_ev4.8
Apart from the helicopter (t= 9:00), I think the recording came out to be quite relaxing. Early Sunday mornings are really the best option to avoid too much road noise – though it can never be avoided 100%.

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Posted by: recordingsofnature | February 19, 2016

Winter night recording, Sømosen Ballerup

This is a night audio recording from Sømosen in Ballerup [map] 15-16.2.2016. Sømosen is a small bogland with shallow waters and reed beds. This bog is formed when a block of ice was left melting as the last Ice age retreated (a kettle), and is one of many in the  Sjælland and Copenhagen area.


Calm and clear night with temperatures dropping to freezing  -7C in the morning.

It’s winter and almost dead silent during the late hours. At dusk and dawn, there is more activity, and here the nature sounds are characterized by lots of magpies, calls from greylag gees, grey heron and mallard ducks. Listen in Headphones.

Dusk, 17:30-18:30, from getting dark to pitch black. Magpies starting a very noisy campaign at 29 minutes into the clip.

Night, 2-3 am. Generally just relaxing and sleepy atmosphere over the bogland as traffic sounds are more faint. From time to time the silence is broken by calls of gees, ducks or heron.

Dawn,  6:45-7:15 am.  Lots of magpies flying around microphones from 15 minutes into clip.

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Posted by: recordingsofnature | February 8, 2016

Copenhagen urban night sounds. Meteorite sound bonus.

This is a field recording from Copenhagen Saturday evening and night of February 6th 2016.
It is really just hours of monotonous and endless street noise of passing cars and other sounds of the breathing city.

For every 15 minutes you can hear the Town hall bell strike from its high tower about 6 km away. It stops after midnight, but it is surprising how clear those bells cut through.

By incredible coincidence I was lucky to capture the sound of a meteorite falling though the sky. Fragments of meteorite were afterwards found in Ejby and Herlev, some 15 Km away (link). So watch out for a deep boom – somewhat like faint thunder – at about 22:08 in the second clip.

Headphones highly recommended.

1) Recording from 17:45 till 19. Starting just after sunset, dark.

From about t=13:30 church bells around the city is ringing the sun down.

2) Meteorite sound, recording from 22 -22.15

At about 22:08, watch out for deep, highly subsonic, meteorite boom.

3) Early morning from 3 – 4:30 in the morning)

At t=6:47 some fireworks.

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Posted by: recordingsofnature | December 25, 2015

Simplified microphone design to mimic binaural forward elevation cues

In this post, I will try to come up with and test a simple microphone design which can produce certain directional cues to enhance the spatial feel of stereo audio recordings, particularly the forward up and down sensation.

Stereo recordings are normally based on volume level difference and time difference between the microphones. Typical used techniques include ORTF, M/S setup eventual combined  with a baffle between the microphones (such as a Jecklin disk).

Information about elevation is however largely missing with these stereo methods. In principle, it is not directly possible to tell if a sound comes from above, down, front or back. Binaural microphone techniques (using anatomical ears and dummy head etc.) are able to provide full directional sensation by reproducing the delicate spectral coloring (HRTF) from the human ear and head/body, which tells the brain about the direction of the sound. But this method has a few drawbacks in terms of personal differences and dominating resonances which need post equalization.

So, here I will try to develop a simpler microphone shape which can mimic the up/down directional sensation of the binaural method to improve the forward up and down sensation of my nature recordings.

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Posted by: recordingsofnature | December 7, 2015

Pine forest in December, Windy

Audio recording Sunday morning about 9 o’clock, 6th December 2015 in Brøndbyskoven near Copenhagen, DK.


Pine forest, Brøndbyskoven

Trying to catch some of the winter atmosphere in the forest,  though the temperature was warm – about 10C. Again windy, but otherwise not much happening. All leaves are now gone, but this didn’t make much difference as this recording was made in a section with pine trees. Pine forests produce a rather anechoic feeling, where all sounds are rather muffled. From time to time, you can hear the wind cut through with soft but yet powerful blasts. Again, the deep motorway rumbling is a bit dominating.

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Posted by: recordingsofnature | November 14, 2015

Windy November forest – going semi-binaural

Forest recording of a warm windy, and sunny Sunday morning, November 8th 2015 around 9:30 am. Appx 10C. The recording is from almost the same spot as the June all-night-recording.
Leaves have just fallen these days. A quick storm passed through the country during the night, and it has really helped thin out in the treetops. In the morning, waves of windy gusts were still blowing through the forest, though at the forest bed was barely more than a light breeze.
November forest and microphones on tree trunk
The sound of rustling leaves has changed into a more light and thin nature, with the addition of a deeper howling from the bare branches.

Sunday mornings are the time where the nearby motorway noise is at a minimum, still it is a throughout present sound.

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Posted by: recordingsofnature | October 14, 2015

Windy field recording in Vestskoven, October 7th 2015

This is a field recording from Vestskoven (@ 55.690108, 12.387271) 7th October 2015, on a typical Wednesday at about noon. Vestskoven is an about 50 years old forest area situated just outside Copenhagen. It is a very nice area, however – from a field recorders viewpoint – it is cut through by several noisy motorways and industrial areas.

Tree ears microphones in Vestskoven October 2015It was a very windy day. It is now rapidly getting colder, but the forest is still green and dense, with leaves and vegetation from top to bottom.

This time, I think, the recording did not really turn out very spectacular or pleasant, but still it serves to capture and document the season’s typical sounds.

At this time there is moist vegetation and damp surfaces in all directions. This effectively absorbs sounds and attenuates any reverberation or echoes. I think this makes the soundscape a bit muffled and not very deep.

The dominating sound is the characteristic sharp hiss of the leaves in the windy tree tops. Birds were just very quiet that day. Apart from that, an extensive and throughout deep rumble from road and engine noises is ever present. I believe the windy condition has helped to enhanced this rumbling and made it even more diffuse and undefined.

Tree tops vestskoven october 2015  Vestskoven forest floor and tree ears  forest floor, vestskoven october 2015

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