An Interview with David Bonnett, Acoustical Engineer Studying Pink Dolphin Communication

by Captain Bill

An Interview with David Bonnett, Acoustical Engineer Studying Pink Dolphin Communication

Hello Dave, welcome aboard Dawn on the Amazon III. Would you please share with us how you became interested in acoustics and trained as an acoustical engineer?

Thanks Bill, my early acoustical interest came as an officer assigned to nuclear submarines during the Cold War, playing cat and mouse with the Russians for 20 plus years. We monitored every sound they made as well as every sound we made.

What have you been doing since then?

I spent many years after retiring from the Navy in 1979 working on a variety of projects that were usually related to shipborne acoustics. One of those projects was for Shurgar, built by the Agha Kahn. That vessel was 80 meters in length and used a Jet propulsion system, thus the need to quiet things down as much as possible.

The Aga Kahn must be the kindest, most modest man who ever owned an eighty meter mega-yacht. You would really like him. Here he is, the spiritual leader of the Ismailis faith, in charge of billions of dollars of investment money, starting a multi-million dollar micro-loan program in the third world, publishing The Nation, one of the most read newspapers in Africa, and sitting around a table just like we are, chatting about life and how to make the Shurgar run quieter.

How did you get interested in Pink Dolphin communication?

We recorded whale communication in the Artic Circle off the coast of Alaska. You know water temperature affects sound transmission? You know the hydrophone picks up all sounds under and on the water? We presented our findings to the Acoustical Society of America. My partner started our presentation with a recording. He introduced it with these words, “This first sound is Mr. Bonnett urinating off the bow of the trawler…” I didn’t even know he was recording. How embarrassing. Let that be a lesson to you. Anyway, I bought this system from Joe Olson, from Seattle, with the idea to record whale communication near our cabin off Puget Sound, Moon Rise Cove. Then a trip to the Amazon made me realize the Pink Dolphin is the member of the Whale family that has been studied the least, and I decided to collect some data on our next trip, and here we are collecting data from Dawn on the Amazon III.

Do you think the data will be usable by scientists?

I believe if we are lucky, we have an opportunity to record scientifically usable data, if we record in a scientific manner, which we did. The big question is, “Will we be able to detect clues that will differentiate between individuals as we can with whales? I believe we will begin making strides in that direction by taking photographs and videos of our subjects. We will try to lay the groundwork of combining photographic and audio imprints of individual pink dolphins and how they interact with their surroundings, while recording their communication.

Dave, would you please share with us your observations about how we came to be here under these circumstances?

The reason I am on this vessel along with my wife Dorothy and our great friend Shirley Sherman, is several months ago Dottie discovered your website,, by reading an article you wrote for the Iquitos Times on the internet. You mentioned you had built a boat to go on the Amazon purposely designed to be very quiet, with a large bank of deep cell batteries that allowed the use of refrigeration, computers, and other minor electrical loads for a long period of time, without running any motor, or generator. I decided it might be feasible to record underwater sounds in the Amazon area that we would travel to, and, in particular, I discovered there were very few quality recordings of the Amazon River Pink Dolphin. Because it is potentially considered to be a threatened species, there was some immediate importance, I believed, in experimenting on using a vessel like the Dawn on the Amazon III as a platform to do these recordings.

Did we help you accomplish your objectives?

We have over 25 gigabytes of very high quality digital sounds from a variety of locations in and around Pacaya Samiria. The Dawn III worked beautifully. It was an exceptionally quiet vessel.

We were able to record many, many dolphins from the deck, dangling the hydrophone from your fishing pole into the water. I think everyone who heard the noises these animals make were fascinated, including your Peruvian guides and crew, who live with the dolphins but never have had an opportunity to hear their vocalizations in the wild, under the water.

I have five or six DVDs worth of dolphin sounds that will need to be further processed and analyzed. Hopefully this information will be usable to the academics and researchers who are interested in this field of endeavor.

Dave, I am very happy to have been part of this research. If you do not mind me saying so, you are overly obsessive-compulsive about your science.

No, I am not, Bill. I think I am just right.

Well, I think I am just right too, but then, my final question would be, why are Dottie, and Shirley laughing so much?

I hope you will enjoy the photos of our journey to Pacaya Samiria National Reserve on my online Flickr photo gallery at Click the link on the right side of the Flickr page titled, Expedition to Pacaya Samiria National Reserve. There you will find over 20 photos of Pink River Dolphins mixed in with beautiful birds, monkeys, incredible insects, trees, food and our guests. Look around the photos, maybe you will find something else of interest.

An Interview with David Bonnett, Acoustical Engineer Studying Pink Dolphin Communication

Bill Grimes, Pacaya Samiria National Reserve, Dawn on the Amazon Tours and Cruises

Related articles about our Amazon cruise to Pacaya Samiria to study Pink Dolphin Communication;

I am just another travel man

Observations About Our Study of Pink River Dolphins in Pacaya Samiria National Reserve

The Pacaya River

Our Adventures Apprehending Paiche Poachers in Pacaya Samiria National Reserve

{ 5 comments… read them below or add one }

1 David Bonnett March 29, 2007 at 4:47 pm

Thanks for the press. I have not yet found the time to really dig into the data we collected but have looked at selected samples and can report that we did record some interesting Pink Dolphin sounds. The way I plan to “reduce” or analyze the data is by using several computer programs that will break down the recorded underwater sounds into time and frequency spectra that measure the pitch and amplitude of short time slices of an individual recording. Much of what we recorded we could not hear through our headphones because the dolphins generate the sounds at frequencies above the range humans can hear. Indeed, I can see that my portable digital recording system which will record up to 45 Kilohertz still fell short in capturing the highest components of the dolphins sounds. We expected this limitation but still we acquired wild dolphin recordings at much higher frequencies than any I have found in the published literature. In order to extend the recording range to cover the highest possible frequencies, it would take a much bigger system which would not be very portable so I think the trade-off was worth it.

Already, the word is spreading about our project. I am in communication with a graduate student in Bangelore India who has asked for advice on how he should set up to record and study the Ganges River Dolphins. I plan to do a “quick look” analysis within the next month so will keep you informed. Anyone interested in doing high quality acoustic recordings both above and below the water in the Amazon River area of Peru could not find a better platform than the Dawn III from which to collect such recordings. The jungle sounds we recorded on deck with our microphone are rich, lush and just what I hoped for to add sound background when presenting the results of the study.

Dave Bonnett

2 Bill June 10, 2007 at 10:16 pm

Hi Dave,

Something funny, everyone wants to see the photos and hear the recordings of the Pink Dolphins having sex. I sure hope that was not a once in a life time opportunity. I want another chance.


3 Trevor Wills August 30, 2011 at 1:28 am

Hi there,
I was wondering if you could me get in touch with David Bonnett regarding possible access to his sound recordings?

I’m a professional 3D animator, and I’m making a short film about the pink dolphins of the amazon.
Some authentic sound recordings would be most beautiful and helpful. 🙂


4 Captain Bill August 30, 2011 at 9:17 am

Hi Trev, sounds fascinating. I’m sure enough Dave will be interested in you project to send you his email address as soon as I reply here. Thanks for finding my blog article and for your interest.
Best regards,

5 CĂ©dric April 21, 2013 at 3:13 pm

I had the opportunity to meet Dave yesterday and to listen to the records and it’s the first time I can heard vocals of pink river dolphins! It’s amazing and there is still a lot to study and discover. Moreover if it’s possible to use the acoustic technic to count and locate dolphins, it can have an important impact on the observation methodologies currently used.
Thanks Bill to have introduced me to Dave… and thanks Dave for your time, sharing your work and passion!

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