Acoustics Research and Sound Gallery
Dr. Aaron Thode of Scripps Institution of Oceanography at the University of California in San Diego, California began investigations of the underwater sounds and noise in Laguna San Ignacio in 2005. Dr. Thode and his graduate researchers are continuing these on going investigations today.
Sound is the primary sensory mode for gray whales and many other animals that live in the ocean. While visibility is often very limited underwater, sound travels about five times faster in water than through the air, and much farther due to the greater density of water. Cetaceans have evolved ways to use underwater sound to navigate when they cannot see, and to communicate with each other often over great distances. While we don’t understand the function and significance of many whale sounds or “calls,” several different "calls" have been recorded in the presence of gray whales during the winter months. These include “Frequency Modulated” and “Pulsive” calls.
“FM” means “Frequency Modulated” – the frequency of these calls, or pitch, is changing while the whale is producing the sound. The frequency can either go higher in pitch (called an upsweep) or go lower in pitch (called a downsweep). FM calls made by gray whales include “Ronroneo,” and “moans.”
The goal of the acoustics research program is to document the numerous sources of underwater sound in the lagoon, including gray whale sounds, and to monitor those sources of sound over time to identify trends and changes in physical, biological and man-made noise in the lagoon.
Recording Techniques & Methods:
The primary method for monitoring underwater sounds in the lagoons is to place digital recording devices on the bottom of the lagoon in specific areas, and to record the underwater sounds for a month or more each winter. Another method is to use a “hydrophone” or underwater microphone to record sounds from a boat drifting in the lagoon or attached to a whale with suction-cups. Our acoustic researchers have documented the sounds of wind, rain, and the changing tides in the lagoon. Also the sounds of invertebrates like “snapping shrimp” fish, and of course the vocalizations of gray whales during the winter. Researchers have also recorded and monitored the presence and numbers of fishing and whale-watching boats that operate in the lagoon. These recordings document the diversity of sounds and their seasonal trends.
In this “Acoustic Gallery” you may select and listen to examples of the sounds recorded in the lagoon and learn about what the researchers have discovered about their frequency, intensity, and diversity within the lagoon during the winter months. There are examples of sounds from gray whales, fish, invertebrates, the wind, rain, and the tides. There are also examples of the sounds produced by whale-watching and fishing boats that operate in the lagoon. Each example includes a brief description of the recorded sound, a “spectrogram” or picture showing the frequency of the sounds over the time, and an audio recording in MP3 format that you can play to hear the sounds.
Many of these recording are of low frequency sounds, and they are best heard on a computer sound system that has a wide frequency response including the lower frequencies. You can also use a pair of good quality headphones to accurately hear these recordings on a computer. If you are a educational institution, museum, or other non-profit organization and wish to obtain copies of these recording, please contact us.
Gallery of Sound Recordings of Gray Whales and Other Species in Laguna San Ignacio
-
Underwater Sounds in Lagoons
In this recording the most obvious sound is from snapping shrimp that sound like frying food. The “bongs” and “gurgiling” sounds are made by gray whales, and very low frequency “rumbling” of croaker fish. The wind blowing across the lagoon creates small waves and bubbles on the water surface (chop) and these bubbles produce sounds as they burst. You may also here some distant boat or “panga” noise in this recording.
-
Gray Whale "Knock" Calls
These "Knock" calls are include “Pulsive” calls. “Pulsive” calls are comprised of individual or a series of “pulses”, or “beats”.
-
Croac (S4 Call)
This is a recording of a gray whale S4 or “Croac” call recorded in Laguna San Ignacio. This call reminds us of similar calls made by frogs and is one of the more interesting vocalizations known to be made by gray whales.
-
Conga (S8 Call)
These recordings are of gray whale “Conga” or “S8” calls recorded in Laguna San Ignacio. Congas are one of the most frequently heard sounds produced by gray whales.
-
"Belch-Like" call
This recording of a gray whale “Belch-like” calls are pulsed “metallic bongs” and “burps.” These calls are often mixed with “Conga” calls recorded in Laguna San Ignacio.
-
Ronnoneo Call (S9)
The low frequency S9 “Ronroneo” call was first described by Anaid Lopez Urban while conducting research in Laguna San Ignacio for her Master’s degree at the National University of Mexico in Mexico City, D.F. (UNAM) in 2010.
-
Mixed Gray Whale Calls
Here is an example of several whales calling in a group.
-
Bottlenose Dolphin (Tursiops truncatus)
The Bottlenose dolphin (Tursiops truncatus) permanently reside in the lagoons and coastal areas of the Baja California peninsula. Bottlenose dolphin use sound to “echolocate” and navigate through the murky water when they cannot see. They produce broad-band “pulsive” sounds called “click trains” or “buzzing” sounds that reflect back as echoes that the dolphin can hear, and use to identify objects and to navigate through the water. They also make hight pitched "signature" whistle calls during social interactions.
-
Croaker fish calls
Fish of the family Sciaenidae are called Drums because of the “pulsive” sounds they make with their resonating swim bladders. Corvinas (Cynoscion spp.) are common in the gray whale wintering lagoons. Calls by “croakers” increases each evening when these fish vocalize more than any other time of the day. They are a major contributor to the low frequency noise in the lagoon, and they can produce sound for hours at a time.
-
Snapping Shrimp
Snapping shrimp are one of the loudest animals in the ocean. They make pulsive sounds by using their claw to create bubbles. When these bubbles burst (called cavitation), it creates a sound wave that we can hear. Many shrimp creating and bursting these bubbles blend together in what sounds like frying bacon. The species found in the lagoons are: Crangon dentipes and Synalpheus lockingtoni.
-
Gray whale response to passing panga
In this recording we first hear gray whales making “Conga” and “Burp-like” calls. As the panga approaches, the whales call more frequently, and then stop calling as the panga sound increases.
-
Underwater sound produced by a panga
As the panga approaches and then passes the acoustic recorder, we hear the frequency of the sounds shift from higher frequencies to lower frequencies, and then shift back to higher frequencies (from left to right in the figure). This change in frequency is known as the “Lloyd’s Mirror Effect.” The sonogram of this sound clearly shows the amount of change in the frequencies captured by the recording device.