DIY Recording Gear – Tree Ears 2

Tree Ears 2 is not so much an evolution from the original Tree Ears microphone mount and windscreen system, but rather an additional lightweight stereo Tree Ears option that is inexpensive to DIY and fairly easy to build with some basic soldering, sowing, and crafting skills.

While I do not at this time have photos of the steps to build one, hopefully these photos, sound recordings, and explanations will inspire some to experiment with DIY stereo microphone arrays for nature sound field recording.

All of the examples above, except Example 5, were recorded with the Sony PCM M10 portable recorder. The microphone capsules (in all examples) were the discontued Primo EM172 capsules. The EM172 has been discontinued andreplaced with the EM272 which is described by Primo to perform basically the same.

It should be noted the EM172 have self-noise too high for recording natural soundscape locations with quiet and subtle background ambience. The Sony PCM M10 also is not really suitable for recording really quiet locations, but it is a pretty good match for the EM172. While it is possible the Tree Ears 2 could be adapted to higher quality, low noise microphones, the benefit of using the very small capsules is that it really helps with portability.

Here is a brief history of Tree Ears and why I created Tree Ears 2.

Back around 2002, I created the original Tree Ears system of DIY microphone mounts with wind-shields to use with Shure Wl-183 microphones. An old webpage I made about my Tree Ears is is still up today:

rockscallop.org/how/183/183mount01.html

The original Tree Ears idea was inspired by soundscape ecologist Bernie Krause. I had attended a Nature Sounds Society field recording workshop where audio engineer, inventor, and nature sounds recordist Dan Dugan told me about this very simple quasi-binaural technique which is also described in one of Bernie Krause’s books:

“Experiment by tying a piece of string around a tree about the diameter of the distance between your ears.” “Clip two omnidirectional lavalier mics opposite each other at the widest point.”

Bernie Krause, Wild Soundscapes: Discovering the Voice of the Natural World, 2002.

My original Tree Ears system still works very well for me, it is very lightweight, durable, and capable of making some great recordings.

In the early 2000s, I had also been experimenting with DIY arrays based on the Crown SASS stereo microphone. The SASS is a quasi-binaural stereo, baffled, boundary-mic array. Professional nature recordist Lang Elliott, had been modifying the original Crown SASS body, adapting it to use the highly regarded Sennheiser MKH 20 microphones. Georgia frog expert and nature recording artist Walter Knapp had been making those mods to the SASS, and sharing his methods on the Yahoo naturerecordists group. “The group” has since moved from Yahoo over to Groups.io. At the time on the group, there was also an ongoing DIY discussion led by nature field recordist and audio post-production expert Rob Danielson, and number of contributors were experimenting with building and testing homemade versions and variations based on the SASS configuration.

One limitation of original Tree Ears is it required an object “diameter of the distance between your ears” to create a binaural stereo effect. Head-spacing alone is not enough to create a good stereo image with omnidirectional microphones – there also needs to be some sort of a baffle between the mics to shadow each mic from the other. Adding a nose like what’s on on a SASS seemed to make sense. Using boundary plates with a fixed angle between the directional axis of each microphone, also seemed like it would help with consistency of stereo image. To keep it small and light, I had to compromise away from ideal dimensions for an optimal stereo image, but what I came up with for the Tree Ears 2 seems to work pretty good.

The basic structure of the Tree Ears 2 body is made from some sheet metal cut to shape and bent to appropriate angles. Boundary plates made from thin plywood, and baffle nose made from open cell foam were glued on. Microphone capsules compatible with (PIP) plug-in power were wired to a 3.5 mm mini-jack to work with small recorders that provide PIP. The mic capsules with rubber boots were inserted through holes drilled in the wood boundary plates. All wire connections were all hot-glued securely and also protected by foil tape against back of the sheet metal body. Wind screens were made of spacer mesh sown into domes to make space between the capsules and fabric. A layer of soft camo-print fabric was put over the whole thing. An optional tripod mount made out of a square of plywood with a screw adapter is removable, and is held on by elastic cord.

If you have question or comments, please either reply to this blog or look for my contact link at oregonsoundscapes.com.

John Hartog

Natural Soundscape Recording,

Portland, Oregon USA