The Reichelt Program for Oral History

Florida State University

Tallahassee, FL 32306-2200

(Robin J. Sellers, Director)

Kohler: During this time [circa 1951] I got involved with Dr. Kellogg of psychology. I had done a lot of work for the psychology department as a whole and got to know Dr. Kellogg. One day we went out on his sailboat, and we were just sailing along -- he had a beautiful little sailboat -- just sailing along and here come the porpoises right up by the bow riding the bow wave. This was in the summertime. He was looking at those things. This guy had more sense under his fingernails than I have in my head, you know. He was really a sharp nail. He looked at the porpoises, and he looked at the water, and we passed a stake or something in the water -- you know a fisherman would always mark a place by driving a stake down in the bottom. And he'd say, "Bob, how do they keep from running into these stakes? Or for that matter, from running into the boats." And, just joking, I said, "Maybe they have sonar." I knew that bats had sonar, and so did he. In fact, another man named Kellogg is the one who discovered this, and there's no relation.

Anyway, Kellogg decided by gosh he was going to find out, so he started working on the porpoise problem. We would go out in the gulf with our equipment. I had to build a hydrophone, which is nothing but an underwater microphone. I had a couple of them built we could take out in the gulf. They would pick up anything, any sounds out there. They are very, very sensitive. We had a 300 foot pier out into Alligator Harbor, 300 foot concrete pier. We could set the hydrophone in the water at the end of this pier, drop it down five or six feet in the water. And then on shore, which was at least 300 feet away, there was the foundation pillars for this same dock. You could stand there on shore by this foundation pillar, rub your finger on the concrete, just slightly like that, and pick it up on the hydrophone, it was that sensitive. We would hear these funny noises. There was one that went "boom, boong" like that. It turned out that it was the old ugly toad fish, who did that little song. We found out many other organisms make all kinds of sounds in the water. But little of this was done at that time and nobody knew much about underwater sounds. In fact, the sounds underwater are almost deafening. You have all of this "klickety-klackedy, klickety-klackedy, klickety-klack" going on all the time. We found that this is from what they call snapping shrimp. It's some of the plankton that is in all saltwaters around the earth.

We got close to some porpoises and could hear that they were producing some sounds. They make two kinds of sounds that we could determine right then. One was a clicking noise that Dr. Kellogg called the creaking door sound. It would go, "Errrrrr" like that. It would start at low pulse recurrence rate and then go up to a higher one. The second sound was [whistles to demonstrate sound]. Well, I had worked on some radar in the Air Force that used radar waves very much the same way, except you couldn't hear them, of course. They used this in an altimeter to measure the height above ground that a plane was flying. When you tune that thing up, it was accurate to within a few feet. It was that good. It was using an F.M. signal, a signal that changes it modulation with time, I mean its frequency with time. It was that second whistle that the porpoise was using that told Dr. Kellogg that would fulfill one of the requirements of a sonar signal. Now the other one, that creaking door sound, I'm not sure from listening to it. So he said, "Let's get it analyzed." "Yeah, yeah. Do you know how much a band pass analyzer costs?" "Yeah." No, he didn't know. It turns out a band pass analyzer is 300-something thousand dollars for a basic one. Now, they could probably build it for $25. We found out that the guy that I went to graduate school with, Roy Donegon, had taken a job at the Mine Countermeasures Station down in Panama City. In talking with him, he said, "Well, heck, we got a big Fairchild band Pass analyzer. Why don't you just come down here and analyze your sounds, and let's see what it is." So, all right, we went down there, and they had a big room full of that thing. It must have cost ten million dollars. It was really a big one. We put the sounds in, and we found that they were first discrete pulses ___________(??), but on the top of each pulse was a frequency that as the frequencies of these pulses went up, so did that top frequency. We found that they could produce sounds up around 120,000 cycles per second, from low to high. From low in the regular sonar frequency and below. I told Dr. Kellogg that here you have two sonar signals that would be capable of being used as sonar if this animal knows how to do it.

So, what was the next trip? We had to go then to observe some captive porpoises at Marineland. Marie [Kohler's wife] joined us down there, and Dr. Kellogg and I and a graduate student whose name escapes me now, would watch through the portholes at Marineland, the porpoises would swim around and around that tank mostly. They continually were making these sounds. We had in the meantime developed a system where I could put sounds back in the water at any frequency I wanted. I had a real dandy audio oscillator that went up that high. I built an amplifier that was linear to over that frequency, and we could produce these sounds in the water. We borrowed a sound projector from the Navy. They had one that would handle frequencies that high. It was a sonar projector. About that high and had a big glob on top and a big blob on the bottom.

We knew the porpoise were very cautious critters. By that time we had learned quite a bit about porpoises, about porpoise behavior. We had our carpenter shop make a dummy model of this Navy sound projector out of wood, weighted down heavily with lead so that it would sink to the bottom, and painted it gray just like this Navy thing is. We took it and put it in the pool at Marineland and let it sit there for a couple, three weeks so the porpoises would get accustomed to it. When it first was put in there, they would swim around. They would dart and move around this way and go around it and continue around. You could see them cock their heads over and look sideways at it and finally they would get where they would come up close to it. Then we put in the real one, slipped it in one time, and started producing our sounds into the water. We started out at a low frequency, and we would all watch to see if the porpoise would respond when we would pump the signal into the water. The porpoise would always turn their head to see where it was coming from, and then as we advanced the frequency dial and went up higher and higher and higher in frequency, we found that they could hear up to 120,000 cycles per second, which they call 120,000 hertz now a days. At the time, this wasn't so remarkable to me because I could hear a little over 20,000, 21,000. We continued upping the frequency and found that they could hear 120,000 kilocycles, or 120,000 cycles per second, or 120,000 hertz, for you nowadays people. So here we had the three things that would indicate the porpoise could possibly use sonar. One was the nature of their signals, the pulses and the F.M. type signal. Second, was their ability to hear these frequencies. Third, was their ability to transmit them. They could transmit those into the water.

So, next thing we had to do was prove they actually used this as sonar, but in the meantime, we had gotten a couple of porpoises from Marineland, had a pool dug at Alligator Harbor marine lab station. This pool was eight feet deep and 40 x 60, if I recall correctly. These darn porpoises would just swim around in it like they did in Marineland, and when they would get tired, they would retire to one side or the other. We had two little pens, one on either end of this long pool, and they would go inside there and rest at night or in the day when they got tired or when they got tired of going around in a circle they would do that. Dr. Kellogg designed a system, a grid system that would drop metallic poles into the water spaced at about four feet, three feet to four feet. Just wide enough for the porpoise's tail flukes to get through between them with maybe an inch to spare. He made these poles on this grid, and you could let them down through a pulley rope arrangement. From the shore, you let them all down at once, or you could let a few down at once, whatever you wanted to do with them. We found that putting those things down in the water, before we put them in the water, we would pen the porpoises in whichever pen they were at the moment. Then we would drop these poles in the water and open the gate so they could get out. We had a board in the back that we could move forward to force them out. The minute they would get out, they would scoot for the other end because they knew we were messing with them. They didn't want to cooperate, I guess. But we found they would haul it for the other end of that pool, 60 feet away, and there must have been 40 or 50 poles, at least on the way there. They never hit one. These poles were designed, they were triangular pieces of sheet metal, of galvanized iron, and they were designed so that when something hit them they would kind of ring. They never hit one. We figured, well, they can see them in the daytime, let's eliminate that. He wanted to blind them, blind the porpoises. I said, "No sir, not with me around you're not going to blind them." We'll figure out another way. So, we figured out we would do it on a night that was dark, no moon. We did this, and we did it hundreds of times. Never hit the tin with their tale flukes at all. They would swim just as fast through that water. To cap the climax, I recorded their sounds as they were going through this grid of poles. We had received a dandy recorder from the Navy. It was a big Ampex capable of recording up to that high frequency. I would play their own noise back to them as they were going through again from the other direction or whatever, it didn't matter. We tried all these thing 100 times or more on dark nights. This took a couple of years to do all this testing. We had one contact with a tail fluke. Only one in all that time, which was rather amazing because I couldn't swim through those things without hitting one and these guys were bigger than I was, particularly broader than I was, and they would go right on through it.

Then we did some other experiments to prove they used sounds as sonar signals. We would let them in one pen or the other and then in the opposite pen, we would have a glass door in front so the porpoise couldn't get in. The glass door in front of where we were working. The porpoise were funny about eating. They would eat mullet for most of the year, but there would come a time in the year when they wouldn't eat any more mullet. They just wouldn't eat, and we didn't want to starve the poor things, so we started experimenting with different fish, and finally we found that they would eat blue fish. Well, blue around Alligator Harbor are hard to come by, so we had to get them from down in south Florida somewhere. There comes a time where they would only eat blues, we would put a blue fish behind the glass in our pen, raise the glass on both pens, and the porpoises would stick their heads out of their pen getting ready to come over to this pen, and they would sound, make their "Errrr" or [whistle] and if it was blue fish eating time, boy here they would come. Right to that fish. Straight to that fish. We didn't have the poles in the water then. If it was mullet feeding time, they would come straight to the mullet. If we put a mullet there when we knew it was blue fish eating time, they would stay in their pen. If we put a blue fish there when we knew it was mullet feeding time, they would stay in their pen. That was additional proof that they were using sonar and that it was so refined, they could tell the difference between the blue fish and the mullet. That's pretty good.

And then, I decided that I would try something funny. I brought a couple of bbs down with me. The porpoise when he is at rest will automatically make a sound burst every few seconds. They automatically rise and fall to breathe, too. They have to breathe air. They aren't a fish like a lot of people think. They are a mammal, air-breather. You would listen to their sounds. It was silent. Nothing was going on. You could hear this [makes deep noise to demonstrate] every couple of seconds or [whistles to demonstrate noise] every once in a while, you would get that. I think they used the F.M. sound, the whistle sound, more as an identifier to try to determine what there is than to determine if something is there. I think their exploration pulse to see if there was something out there was the "Errrrrr" creaking door sound. Anyway, we would let them be at rest for some time. Then I would take a bb and drop it in the water. One lousy bb and immediately both would [makes deep, fast noises to demonstrate] you'd hear that. Then [whistle] and that was all. By that time the bb had hit the bottom, and they and they are at rest again. They figure it is just something dropping from the sky but I don't really know what they figured. I didn't ask them. They were that sharp. You know, a bb is just a little tiny fellow and doesn't make much of a splash when it hits the water, but all the way across that 60 foot pool, they would hear it.

They had phenomenal ears. Dr. Kellogg got to dissect a porpoise head at, oh, somewhere around St. Petersburg. I forget just where it was but there was one of the show places there that had a porpoise that died, and Dr. Kellogg put out the word that he would like to dissect ones' head to see what their hearing and sound producing mechanism amounted to. He dissected this thing and got the ear bones out and brought them back to me. He had done a lot of research on it and found that porpoise ear bones were some of the oldest fossils there were. They were so hard, they survived for so many years. He was able to dissect them and, sure enough, they are hard as glass. He dropped one on the table and it shattered after it had dried out. Just shattered. He found that their sounds are made with their blowhole up on top. They kind of modulate the blowhole so, they got the hole there -- they are nostrils actually -- and this flap of tissue is over them and it goes back and forth. When they reach the surface, they pull it back real fast, and that's when you hear them go "puff," breathing out, and then breathing in they leave it open while they are in the air, but the minute they get under water that things closes tight so they don't breathe in any water. They can modulate it, they have fine enough control over it, where they can close it almost but just a little open enough to make a little air go through to vibrate, like your vocal cords. It's same as your vocal cords.

So we pretty well proved that they had sonar. In the meantime, we had gotten a letter from Woods Hole Oceanographic Institute from a guy named Sheville who was interested in porpoises, and this letter berated us something awful. Said you guys are just crazy. You cannot possibly have a mammal like this that uses sonar and all kinds of nasty stuff, saying our science was no good and all that. But then we proved that they did have it, and it wasn't long that old Sheville was writing us to find out how we did it. He became right friendly to Kellogg. He didn't to me. I wouldn't have anything to do with that hard head. Anyway, that was a very interesting part of my work. That was one of the main reasons why I left the radio station because of this porpoise research.