To gain new insights into how dolphins communicate, researchers at Tokyo University of Marine Science and Technology and  Fusion Inc. created a prototype of an extremely broadband “dolphin speaker” capable of projecting dolphins’ communication sounds, whistles, burst-pulse sounds, as well as detection sounds such as echolocation clicks.

Dolphins rely on the combination of a variety of vocalizations and vastly better acoustic abilities than humans to communicate with each other or to detect their surroundings and prey in the dark sea.

The researchers will present their research at the Acoustics 2012 meeting in Hong Kong, May 13-18.

Dolphins can hear and produce sounds of up to 150 kHz, which are too high for humans to hear, and can vocalize at a variety of frequencies simultaneously.

“Acoustic studies of dolphins that have been done so far focus mainly on recordings of vocalizations and hearing abilities, but relatively few playback experiments have been conducted,” explains Yuka Mishima. “There were no speakers that could project from low to high frequencies like dolphins, although some could project the low-frequency sounds or parts of dolphin sounds. We succeeded in developing a prototype broadband transducer for an echosounder … by using new types of piezoelectric elements that had never been used for underwater acoustic transducers.”

Their dolphin speaker prototype can project sounds in the 7 to 170 kHz range.

“The dolphin speaker will enable us to play back a variety of dolphin sounds to dolphins, which will help to broaden the research of their acoustic abilities,” notes Mishima.

Ref.: Yuka Mishima, ‘Dolphin Speaker’ to Enhance Study of Dolphin Vocalizations and Acoustics, ASA Lay Language Papers, 163rd Acoustical Society of America Meeting, 2012 (open access)

Ref.: Yuka Mishima et al., Evaluation of playback sounds by a newly developed dolphin-speaker, Acoustics 2012 meeting in Hong Kong, May 13–18, 2012 [Abstract]