The weather balloon recording method

The weather balloon recording method is an exploratory field recording technique that investigates the notion of escaping all sound to locate and record a sonic silence in the stratosphere. As part of my doctorate research at the University of Technology Sydney, weather balloons are used to quietly send microphones and cameras through the troposphere and into the stratosphere just beyond the Ozone Layer to altitudes of 28 – 33km, placing microphones at the edge of the sound world. While there are numerous examples of filmed weather balloon flights in standard and 360 formats, all I've seen are accompanied by inadequate, rudimentary sound recordings captured through low fidelity camera microphones with wind distortion and system noise common issues, or with no sound at all. To my knowledge, this research is still the only example of using weather balloons as a sound centric field recording technique to capture high quality sound recordings of a weather balloon flight that captures the soundscape of the troposphere and into the stratosphere. Sound is the priority with the visuals playing an accompanying role.

The weather balloon recording method investigates: 
  • Exploratory sound recording and the development of a new field-recording technique using weather balloons.
  • Aerial phonography – recording soundscapes from above as opposed to the usual within.
  • Recording the sonic environment of the troposphere and stratosphere.
  • The attempt to place microphones away from all sound on the ground and recording a sonic silence.

Weather Balloon Flight 3 – 15th February 2020.

This flight was recorded in stereo and ambisonic sound, as well with both standard GoPro and 360 GoPro footage, the 360 footage will be uploaded eventually. The stereo recording is what's heard here. Rode microphones sponsored me with an ambisonic mic but unfortunately the more sensitive capsules didn't fair well in the winds at lower altitudes despite 3 layers of wind protection, ambisonic wasn't suited to the methodology. I have however worked out how to best record a balloon flight in both stereo and surround sound for any future flights. More stereo sound with standard and 360 footage will appear here 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.





Weather Balloon Flight 2 – 6th October 2018.

After 6 months of delays caused by strong winds in the jet stream and the higher stratospheric winds I was finally able to complete a second flight. 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 with all adjustments to the payload and recording system making for an improved, and great, sound recording. A GoPro provided great images to support the sound recording. A 360 camera was also used but stopped filming on ascent at an altitude of approximately 25km, nonetheless, some great 360 footage was captured up until this point.

The improved recording raises new research questions within the weather balloon recording method and general approaches to field recording, including aerial phonography; the notion of recording soundscapes from above as opposed to the usual within.

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 the playback volume needs to be increased to extremes for anything to be heard at the highest altitude just before burst. These are quiet and should be listened to through headphones or good speakers in a quiet room.


                             
























Below are stills form GoPro footage that show various stages of the flight form launch, burst point and landing. 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.

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 recording equipment.

This  flight was on the 4th March 2017, it was 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 method to be improved upon (primarily payload rotation and whistling), I did get some great and fascinating sound that was a big step closer to the quality I was aiming for.

Below 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...















The sound recording below is a mono excerpt from approximately 32kms up into the stratosphere and, to my knowledge, the first of its kind. There are some mysterious low frequency sounds occurring, it is currently unknown exactly what these are but the two theories are; they are from a passing plane at a much lower altitude, or from tension created in the line that attached the payload to the balloon. However, I take great care to prevent the microphones from picking up unwanted sounds so the line tension theory is not certain and this will only become clearer after my next flight. But the stratosphere is seemingly a very quiet place and I feel in the future I maybe be able to get closer to a natural silence, or at least the limit of the microphones. Due to this the recording is of course low in volume, headphones or good speakers in a quiet room are best.