Going Wild with Bernie Krause

Feb 21, 2007 2:54 PM, By Gino Robair

How do you pick the ones you're going to record?
If I'm thinking CD or if I'm thinking I want an expression of that habitat, I go for the location with the densest mixture of creatures that are vocal. I'm recording animal music. So I want something that's going to sound.

There are places within the jewel national parks, where you can go to hear natural sound unimpeded. As a matter of fact, the National Park Service is the only federal agency and the only group in the country that has designated natural soundscape as a resource. Because they're a federal agency, it means it must be protected like any other resource.

How do they make that happen?
Part of it is restricting fly overs, snow mobiles, and jet skis. These are rules that they implemented over the course of ten years.

One of the next steps is to establish noise-free zones. What that would mean is no human-induced noise can intrude for 15 minutes at a time. There's a manual from the National Parks called The Nature of Sound, that all of the superintendents have to read and enforce. It's all about soundscape.

Chainsaw noise travels 20 miles through forests. They're pretty loud. Motorboat noise, those diesels with the straight pipe, is a low-frequency sound that carries a long way.

How do you get rid of it?
I usually put a 160 Hz cut on the preamp, which the Sound Devices has. It has an 80 and 160 Hz low-cut filter. I usually put that in and it cuts out some of the longer waveform material. Also, most of the natural sound is above that, ranging from 200 Hz to 20 kHz or more.

Do you use parametric EQ for boosting or to remove audio artifacts?
Mostly to remove artifacts, such as low-frequency wind noise. There's often a low-frequency component to the material in jungles because of distant streams and stuff like that. Low frequencies carry a much longer distance through the jungle and it's just too noisy and too distracting.

When you're transforming this material to a CD, you're transforming it from one medium to another: from the natural world into another medium. And you better make sure it's listenable. That's the art of this. That's why so many recordings aren't very good, because people haven't taken into account that it's being transformed into another medium. They haven't done due diligence to consider how it's being perceived by the other person.

You may, as the recordist, be able to imagine the spot that you recorded it and it evokes an image in your mind. But the listener has no such capability of doing that because they weren't there when you recorded it.

Do you test your recordings on somebody?
I test my recordings on somebody all the time. Typically my wife, to see if she gets it.

Does she often give you the thumbs down on things?
Often. More often than you'd like to know. That's why I spend so much time in this damn studio and wear out so much equipment. She's good because she has a good sense of that stuff.

Tell me about your homemade hydrophone.
It has a frequency range of 3 Hz to 20 kHz. It's designed to work with water, and it matches the impedance immediately.

Sometimes when you drop it into water, it gets little air bubbles around it, which keeps it from matching the impedance, so it doesn't transmit the sound very well. To get rid of the bubbles, you put a little grease on it, like some olive oil. Go online and do a search on hydrophones. Hydrophones go down very low, and this one goes down to 3 Hz.

The neat thing about some of the digital Sony recorders, particularly the D10, is that they can capture infrasound down to 3 Hz. Sometimes you can use the hydrophone as a microphone. I used this in the sand dunes and I also used it to record elephant sounds, because they vocalize around 14 Hz. Giraffes, hippos, and elephants transmit sound through the air at very low frequencies, which allows them to communicate over great distances. Hippos do it under water and in the air. So this is what we use for that.

Do you just hold it when you record with it?
Yes. You have to hold it very still. And it's very sensitive, so you'll hear your muscle fibers firing.

This is one we used to record a tree. Every heard a tree singing? It's 70 kHz. This is a B&K 4103, which has a range of 0.1 Hz to 100 kHz. It's used to record dolphins. The dolphin is the highest frequency creature on the planet. Whales are the lowest on the planet. Their lowest sounds go down to 3 or 4 Hz, because they want to transmit over long distances. And the Ganges river dolphin goes up to 356 kHz.

Do you ever normalize recordings to bring up the level?
Yes. I sure do. After editing and just before I'm ready to cut a master.

How did Douglas Quin approach his underwater recording in stereo?
The Weddell seals that he did are all in stereo. He used two mics set about 10 meters apart. Where we would record in stereo with about 7 or 8 inches between mics, you have to place the mics about 10 meters apart to get a stereo image, or at least a spatial image, underwater due to the impedance and density of water, and the fact that sound travels five times as fast underwater.

How did you know to record the tree?
We were recording bats, and we had a bat detector, which is, essentially, a frequency divider. We were listening for the sounds of bats, which are up in the 47 kHz range. And we heard a steady signal, very unbiological in the sense of being a creature. As we moved closer to this cottonwood tree, the signal level increased.

We drilled a little hole in the tree and put this hydrophone in. We had an instrumentation device with us that could record a frequency that high, and we got a signal coming from the trunk of the tree. We couldn't figure out what it was. Then we slowed it down by a factor of seven, to get it down within our hearing range.

What we discovered was that, during a drought, the cells in the xylem of the tree usually maintain a certain pressure from the water that comes into the trunk during normally wet seasons. When that pressure drops during a drought, the cells automatically fill with air to try to maintain the osmotic pressure. And when they get too dry and they're pumping in air, they pop. When they pop, they die, and the dead cells form the tree's rings.

So, when they pop, they make a noise: we can't hear it, but insects can. And when insects hear multiple cells popping, they're drawn to the tree because certain ones are programmed to expect sap. And when the insects are drawn to the tree, the birds are drawn to the tree to eat. it's all a microhabitat formed by sound: The sound of popping cells.

You've also recorded ants.
People would never think that ants make this kind of noise. If you block an ant hole with a lavalier microphone, the ants will gather under it. And there will be one ant in particular that's directing all the others to dig the damn thing out, and get the obstacle out of that entrance. They're rubbing their little legs on their belly: they're not vocalizing. They're communicating with one another through this kind of stridulation, and it is sound. They're not communicating using pheromones, as most people think, but through sound.

There are different species of ants, and many have a unique sound. If you put your ear close enough, you can actually hear the sound. With that little $14 lavalier microphone, you can hear ants singing in your backyard.

How did you record the singing sand dunes at Kelso?
You kick the sand into motion — it's not the wind that creates the sound — and the dunes begin to resonate in a frequency range between 4 or 5 Hz and 120 Hz. It sounds like a freight train, and you can hear it 7 or 8 miles away. The reason they make sound has to do with the moisture content in the sand.

Do you have any words of advice for budding recordists?
Begin to explore the acoustic component of our world to see what it's really like out there. To the extent that people are willing to take the time to do that, they're going to discover a whole new part of themselves that they never thought of before, because we're so visual. We're not really tactile. We don't really use our olfactory senses at all. We're something like 99 percent visual.

That's largely because the technology for preserving visual stuff has been with us for a long time: we've been drawing on caves for 40,000 years. We haven't been able to capture sound until a little over a hundred years ago. And when we first began to do that, it came very late in our human development of civilization, particularly in the west. We've lost that ability to hear, because it's been put on the backburner, and it's been overcome by so much noise.