The Bioacoustic Probe

News!

November 2007

All inventory of Bioacoustic Probes is now sold. Development of the new design is coming along, the first prototypes are in assembly as of this writing (5 November 2007). However much effort remains ahead, and it is too soon to quote specifications, options, pricing or delivery. At present we are hoping to have the design commercially available in the second half of 2008.

March 2006

Acoustimetrics is pleased to announce Office of Naval Research support for development of a new, wideband acoustic recording tag. The new design will be capable of sampling rates at least up to 200 kHz, with expanded storage capacity and faster data offload. We also hope to move from a 2D to a 3D accelerometer for orientation sensing, and to add compassing ability as well. We hope, but cannot guarantee, that a production version of the new instrument will be commercially available by the end of 2007. To focus our resources on this new development, Acoustimetrics will no longer take orders for construction of new Bioacoustic Probes. We are however building seven units to be available for sale between now and the release of the new design. These new units will have an assortment of pressure transducers (500-m, 1000-m, and 2000-m) and hydrophone sensitivities (-172 dB or -190 dB). All will have 2D accelerometers and 1-GB storage units. We will stock these seven units until they are sold, but will not build any more.

March 2006

New firmware 1.5.2 has been released; see the release notes. This firmware is very highly recommended for B-Probes with firmware versions 1.5.0 or 1.5.1, as it fixes a timestamping bug introduced with those firmware revisions.

November 2005

New firmware 1.5.0 has been released; see the release notes. Two Bioacoustic Probes shipped this week with very sensitive pressure transducers, good only to about 55 feet but capable of resolving vertical changes on the order of millimeters; this took some redesign effort to avoid damaging the pressure transducers during construction. Last but not least, indications are that we will be supported to redesign the Bioacoustic Probe for much faster sample rates. Stay tuned.

March 2004

Two Probes have been successfully pressure tested to 2000 m equivalent depth. This verifies that the design should be capable up to this depth. From here on, every Probe made will be pressure-tested to the full-scale range of its pressure transducer or to 2000 m (3000 psi) whichever is lower.

December 2003

The production version is available build-to-order with a delivery time of 16 weeks. We plan to carry limited inventory in 2004 so that at least a few units can be available immediately. Field experience from the summer of 2003 has been applied to both hardware and software, improving reliability and ease of use. The maximum sampling rate has been increased from 15 to 20 kHz at room temperature; at near-freezing temperatures sampling rates under 10 kHz are now usually sustainable with a typical 1/2-AA lithium battery.

Why is this capability important?

Awareness of the potential effects of human-generated sound on protected marine wildlife has heightened over the last decade. Unfortunately our understanding of such effects remains dim. To focus conservation efforts where they will do the most good, it is urgent that we find ways to assess protected species' acoustic sensitivity.

Historically, the only practical means to assess marine animals' response to sound have been either captive studies at a laboratory or distant observation of selected groups of calling or surfacing animals. Each approach has merits, but neither allows the scientist to study a free-ranging individual's response to accurately quantified sound exposure. The way to obtain this information is to place a sound and behavior recorder directly on a free-ranging subject; until recently, however, underwater acoustic recorders could not be made small enough to be attached to wildlife.

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The origin of bioacoustic tags

The first acoustic recording tags were applied in 1995 by a partnership of the University of California at Santa Cruz, the Woods Hole Oceanographic Institution (both supported by the Office of Naval Research), and the Monterey Bay Aquarium Research Institute. These experiments with northern elephant seals yielded surprising results, showing that the tags' acoustic records contained not only measurements of sound exposure, but of potential response indicators such as respiration and cardiac function as well.

Since the success of these early experiments, studies using bioacoustic tags have expanded. At least three current designs have been applied with free-ranging protected species: the DTAG from the Woods Hole Oceanographic Institution; an ultrasonic recorder from the University of Århus in Denmark; and the Bioacoustic Probe.

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The mission of the Bioacoustic Probe

The complexity of bioacoustic tags renders them impossible to develop for small biology-oriented research groups with few engineering resources. Even larger research groups with engineering capability must focus on advancing immediate scientific goals, not on developing instruments for broad applications.

The Bioacoustic Probe project aims to provide off-the-shelf bioacoustic tag technology for application with large fish, whales, and everything in between. The goal is to enable field biologists, especially those without access to engineering support, to study questions of acoustic sensitivity.

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Concept of operation

Using a PalmOS-compatible personal digital assistant, the user programs the B-Probe with the sampling schedule and rate desired. No other equipment is necessary to prepare the B-Probe, allowing programming to take place in difficult outdoor settings, such as a kayak, that would be unsuitable for heavier or more delicate equipment. The B-Probe is then attached to a subject or placed in a recording location. When recording is complete, the B-Probe must be recovered. The acquired data are then downloaded to a personal computer via infrared transmission.

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Development

The breadth of the B-Probe's mission demanded intense design focus on miniaturization, reliability, and ease-of-use, in addition to the essential data acquisition functionality. Initial development of the B-Probe required over three years of effort. A new computer platform was designed, a new operating system was created, and application software had to be written for both the tag and the PalmOS. The following summarizes the major development components:

New 3-volt hardware platform

A new hardware platform was developed from scratch around the Motorola "DragonBall" 68EZ328 processor, an extreme-low-power device with an industry-standard architecture, and the M-Systems "DiskOnChip", a solid-state mass-storage device.

New 3-volt hydrophone preamplifier

Because the entire design relies on a 3-volt supply, a new hydrophone preamplifier had to be designed that could operate with this low voltage while remaining very quiet and pulling less than a milliampere of current. As part of the Office of Naval Research's focus on technology transfer, hydrophones with this preamplifier are now commercially available from High-Tech, Incorporated.

New operating system

To allow maximum flexibility and power conservation, a new operating system was written from scratch to run on the tag platform.

Industry-standard infrared communication

An Infrared Developer's Association (IrDA) object-exchange protocol was incorporated into the operating system to maximize compatibility with other infrared devices.

Palm commanding

Graphical user-interface software was written for the Palm personal digital assistant to allow simple commanding of the B-Probe, even in harsh field conditions.

Hard polyurethane encapsulation

Complete encapsulation in polyurethane protects the instrument from damage at sea or in handling, and simplifies application. The polyurethane passes acoustic signals and infrared communications, so no external connectors or wires are necessary. While encapsulation confers the advantages of reliability and ease-of-use, it also requires significant effort to be sure that all components can tolerate the ocean pressures experienced by the tag.

Field-replaceable battery

The B-Probe runs on a single lithium 1/2-AA cell battery. A small pressure housing embedded in the polyurethane resin protects the battery while allowing it to be changed in the field.

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Milestones

June 1999

The Office of Naval Research initiates development support for the Bioacoustic Probe.

October 2000

The first prototype circuit boards are fabricated.

March 2001

Four prototypes are deployed, inside pressure housings, as seafloor recorders off Maui to monitor ambient sound levels from humpback song (in collaboration with the Hawaii Institute of Marine Biology).

August-October 2001

Unsuccessful efforts to attach the B-Probe, inside a pressure housing, to blue whales.

November 2001

A prototype is encapsulated in resin for the first time.

May 2002

Tag software feature set completed, version 1.0.

June-July 2002

Several successful attachments to blue whales off the California coast (in collaboration with the Scripps Institution of Oceanography, Cascadia Research, Whale Acoustics, and Cetacean Research Technology).

September 2002

Application with northern fur seals at the Pribilof Islands by Hubbs-SeaWorld Research Institute.

December 2002

New electronic design for production tags completed, providing tilt sensing and much smaller size.

July-August 2003

Several successful attachments to blue and fin whales off the California coast (in collaboration with Scripps, Cascadia, Whale Acoustics, and CRT as before)

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Content last updated November 2007