Weather balloon flights as a method to record the stratosphere

Weather Balloon Flight 3 – 15th February 2020.

After a few delays again I finally got a 3rd flight done. It is a nature recording technique so we have to wait for the best weather.

This flight was recorded in stereo and 360 sound, as well with both standard GoPro and 360 GoPro footage, 360 footage will be uploaded soon. The stereo recording is what's heard here. Rode microphones sponsored me with an Ambisonic mic but unfortunately it didn't fair to well with the winds at lower altitudes even with 3 layers of wind protection, I'll work out a way to incorporate the ambisonic recording into a final video at the higher altitudes in the future. I have however worked out how to best record a balloon flight in both stereo and surround sound for any future flights that may arise. More footage will appear very soon but in the meantime...

Below is an excerpt of a plane fly by at 11km. It's very rare to capture such sound and footage. The wide lens Go Pro makes it look further away, this plane is approximately 1-2km away. The footage is great but this is a great sound recording of a plane at cruising altitude flying at full speed. Watch the top right corner.




Here is some short unstitched 360 footage that uses just the GoPro sound recording which is wind blown and distorted. This is burst point and the initial decent. Using unstitched footage and distorted GoPro sound is some thing I'll pursue with the material I have.





Weather Balloon Flight 2 – 6th October 2018.

Finally! After 6 months of delays caused by strong winds in the jet stream and the higher stratospheric winds I was eventually able to complete a second flight. As part of my research at the University of Technology Sydney I'm still attempting to place my microphones away from all sound and record a natural silence in the stratosphere using a weather balloon. This flight reached an altitude of 33.5km, just above the ozone layer, half way into the stratosphere and 1/3 of the way to space. I made some improvements based on the outcomes of the first flight (see below) with all adjustments to the payload and recording system making for an improved and great sound recording, along with some impressive visuals from a GoPro. A 360 camera was also used but stopped filming on ascent at an altitude of approximately 25km, nonetheless, some great 360 footage was also captured.

This improved recording raises new research questions within the weather balloon recording method and general approaches to field recording, including the notion of recording soundscapes from above as opposed to the usual within and the idea of using both free flying balloons and those tethered to the ground to do so. I am still to complete one more flight within this body of research to advance the technique further.

Below are some low resolution sound and footage excerpts of various stages of the flight. The sound in these excerpts is from the stereo mic setup and separate recorder, the footage is form a GoPro. It took some adjustments to the setup to be able to record clean sound all the way up. As far as I know, it’s still the only research using weather balloons as a sound recording technique to accurately record a balloon flight and the sonic environment in the troposphere and up into the stratosphere. If I dig through the noise floor it’s still not silent up there! But I had to turn the playback volume up super loud to hear anything at the highest altitude just before burst. Use headphones or good speakers!


                             
























Below are some stills form GoPro footage that show various stages of the flight form launch, burst point and landing. These are all raw and unedited straight from the footage but you can see pieces of the balloon after burst before the load begins the initial fast and violent decent, the last pic shows the parachute falling into frame about to hit the ground.
























Weather Balloon Flight 1 – 4th March 2017.

I wanted to place my microphones in the stratosphere to record what may or may not be happening at high altitudes, hoping to record as close to a natural silence as possible. To do this I came to the idea to use a weather balloon as a sound recording technique. To my knowledge, the use of a weather balloon flight as a recording technique using acoustic microphones had not been attempted before my first launch in March 2017.

As part of my doctorate studies at the University of Technology Sydney, I use sound recording to try and capture the most base level sonic layers in our soundscapes, independent of all the primary and obvious sounds of life. In doing so, I record the discrete and distinct acoustic properties of landscapes illuminated by only by the constant and most subtle geographic sounds that always occur. It is a sound that can only be heard in the quietest natural environments, a very rare and difficult to find sound found only in remote places that takes us back to a time before life. I invert our soundscape to look below the noise to a hidden and discrete sound that is all around us but smothered by primarily human sound.

I take the same method and approach of room tone recording for film production to our natural environments. As with a ‘clean’ room tone recording, I attempt to eliminate all Anthrophony (human sound) and Biophony (wildlife sound), and work to limit Geophony (geographic sounds of wind, rain etc.) as much as possible. To capture an uninterrupted clean recording of the sound I chase, I try to avoid even the sounds of insects and vegetation moving in the wind.

I use only standard acoustic microphones and record sound that is happening within our human hearing range.

However, this base level sound is very difficult to capture in the way I aim for on the ground because our world is a noisy place. Anthrophony is far reaching, animal sound is all around and limiting the constant natural geophony is difficult.

I then came to the idea to put microphones in the sky.

Given a weather balloon has no engine and makes no sound of note, it was thought this would allow me to record from the ground up towards a natural silence, the best method to get away form all sound on the ground and record a journey in to the stratosphere. There are numerous examples of filmed weather balloon flights using lower quality internal camera microphones where sound quality is not considered, but to my knowledge there are no attempts to record an entire flight in high definition sound using quality sound equipment.

This  flight was on the 4th March 2017, 2.5 hours long and reached a height of 33kms, a third of the way to space and well in to the stratosphere, just above the ozone layer. This flight largely functioned as a test flight and although there are aspects of the sound recording method to be improved upon, I did get some great and fascinating sound that is a big step closer to the quality I'm aiming for.

This is the most extreme, creative and expensive field recording technique I've ever used and will continue with. The next flight is March 2018.

Thanks to Matthew Stuart for his skills in designing the housing for the recorder and microphones. Thank you to Robert Brand for his weather balloon expertise.


Here is a collection of stills from a video placed on the balloon payload of various stages of the flight, including the final pieces of the balloon at burst point...