People have always been intrigued by the sounds dolphins make in water, and now British and American researchers have succeeded in shedding light on this phenomenon by creating the first high-definition images of these weird and wonderful sounds. They achieved this breakthrough with the aid of a CymaScope, an innovative instrument that reveals detailed structures within sounds.
By using high-definition audio recordings of the marine mammals, the research team was able to assess the sounds' architecture pictorially. British acoustics engineer John Stuart Reid and US dolphin researcher Jack Kassewitz, who led the project, said the imaged sounds are known as 'CymaGlyphs'. According to the researchers, CymaGlyphs should form the basis of the lexicon of dolphin language, as each dolphin 'picture word' is represented by a different pattern.
Most researchers over the years have supported the theory that while certain sounds made by dolphins represent language, the sounds' complexity makes them difficult to analyse. Previous attempts to display the sounds made by cetaceans (e.g. whales and dolphins) resulted in relatively simple graphs displaying frequency and amplitude.
The CymaScope captures the actual sound vibrations imprinted in the dolphin's natural environment, the team said, allowing complex visual details of dolphin sounds to be successfully imaged for the first time.
Cetacean researchers have postulated that dolphins have 'evolved the ability to translate dimensional information from their echolocation sonic beam'. What the CymaScope does is to visualise the dimensional structures within a sound, the team said.
Kassewitz, who also leads the SpeakDolphin.com project in Florida, US, said: 'There is strong evidence that dolphins are able to "see" with sound, much like humans use ultrasound to see an unborn child in the mother's womb. The CymaScope provides our first glimpse into what the dolphin might be "seeing" with their sounds.'
Reid explained that sound travels in expanding holographic bubbles and beams, not in waves as most people thought. 'Whenever sound bubbles or beams interact with a membrane, the sound vibrations imprint onto its surface and form a CymaGlyph, a repeatable pattern of energy,' the researcher said. 'The CymaScope employs the surface tension of water as a membrane because water reacts quickly and is able to reveal intricate architectures within the sound form. These fine details can be captured on camera.'
Based on the results, CymaGlyph patterns are similar to what the dolphins perceive from their own returning sound beams and from the sound beams of other dolphins.
'The technique has similarities to deciphering Egyptian hieroglyphs,' Reid explained. 'Jean-François Champollion and Thomas Young used the Rosetta Stone to discover key elements of the primer that allowed the Egyptian language to be deciphered,' he added. 'The CymaGlyphs produced on the CymaScope can be likened to the hieroglyphs of the Rosetta Stone. Now that dolphin chirps, click-trains and whistles can be converted into CymaGlyphs, we have an important tool for deciphering their meaning.'
Following on from this innovative development, Kassewitz said a series of experiments will be carried out to record the sounds of dolphins targeting a range of objects. 'Dolphins are able to emit complex sounds far above the human range of hearing,' he said. 'Recent advances in high frequency recording techniques have made it possible for us to capture more detail in dolphin sounds than ever before.