Colorado College OVAL Project Home Page

OVAL Schematic The Orca Vocalization and Localization (OVAL) Project uses an array of hydrophones in the Haro Strait of Puget Sound to determine the location of vocalizating orca whales

The OVAL Project is a joint research effort linking the Colorado College Physics Department with the Whale Museum of Friday Harbor, WA.. Our joint project is called SeaSound.

The director of the OVAL Project is Val Veirs, Professor of Physics at Colorado College

Vocalizations of orca whales may be divided into clicks and calls. Clicks are short, broadband sounds used by orcas for echo-location. Calls have a duration of a second or so and are presumably used for communication with other orcas. A "Sonogram" or "Spectrogram" such as you see here is a convient way to examine clicks and calls. This a graph of frequency on the vertical axis and time on the horizontal axis. In this image, frequency runs from 0 to 10 kHz and the time axis displays three or four seconds of data. You see first a sequence of four clicks and then the harmonic structure of an orca call.

Listen to this sequence of clicks and calls

At 3 pm on Wednesday, October 22, 2003 unusual orca vocalizations were recorded. (Click here to listen.) I observed an orca very close to one of OrcaSound's array of hydrophones. This orca's vocalizations have most of their power at about 8 kHz which is much higher than Southern Resident discrete calls. Simultaneously, a comercial fisher was finishing pulling in his purse seine. The orca (or possibly 2) milled around near a reef and when the fisher steamed off to the south, I observed an orca porpoising parallel to the boat, coming up for a breath and a splash every 10 sec or so.

Southern Resident Call Vocabulary: The three pods (J, K and L) that live in the southern portion of the Salish Sea between Vancouver and Seattle use a variety of calls that have been classified by John Ford (Vancouver Aquarium) with contributions by Rich Osborne (Whale Museum).

Ships and Boats make lots of noise in the waters the Southern Resident orcas frequent. Click here to listen and look at a variety of sources of underwater noise.

Here are some additional orca vocalizations. These are mp3 encoded.

Oceans Some Basic Sound Concepts: Click here for an introduction to the terminology and concepts of marine acoustics.

The OVAL array of hydrophones is in the Haro Strait on the west side of San Juan Island. The array is comprised of eight ITC 4066 omnidirectional hydrophones. Signals from the hydrophones are amplified and filtered and brought to a Pentium III computer for data analysis.

The location of an underwater source is determined by determining the arrival time difference for a call or a click at each of the hydrophones in the array. From these time differences the location of the source can be found if the location of each of the hydrophones is well known.

Once the location of an underwater sound is known, a video camera is directed to record the surface of the water over top of the localized sound source. This video allows us to observe orca behavior in the region of the underwater vocalizations.

The population of orcas that frequent the OVAL site each summer is in critical condition. This population was severly impacted thirty years ago when many orcas were taken from this population for marine parks, especially SeaWorld. The population appeared to be recovering from this assault until about five years ago. Since then the population has dropped each year with the total dropping from a high of 99 in 1995 to its current number of 78. (Population data is from the Center for Whale Research) There are three feasible components to the current drop in orcas. The problem may be some combination of food, pollution, and pressure from whale watchers.

Working Students For the last three years, Colorado College physics major students have worked in the field installing and calibrating the OVAL array of hydrophones.