Dolphins can use clicks at different frequencies in far more ways than whistles and can click directly at another animal whereas whistles are not directed. Most research so far has concentrated on clicks being used in echo location and findings can aid development of human sonar devices. The human hearing limit is 20 kHz. It is only recently that the technology to record these sounds underwater and transform them has become available. The electronic saddle pack, designed at Kolmarden, with appropriate computer equipment allows Amundin and Blomqvist to transform the high frequency noises to a level audible to humans.
Dolphins can play with a whole range of frequencies in each click.
They can boost up lower frequencies and pull down high ones or vice versa. The team are convinced dolphins use these high frequencies when they want to communicate directly with another dolphin, sending a high frequency noise in a narrow sound beam of about 10 degrees, which means other dolphins nearby do not hear it. Amundin said this could hold the key to communication by dolphins. A key feature of the research at Kolmarden, which has carried out dolphin studies since 1994, is that Amundin and Blomqvist are not trying to monitor the dolphin that is talking but the animal being spoken to. The electronic recording device on Flip's back, designed over the past two years, records all the noises directed at him and video cameras located above and in the pool film the activity accompanying this noise to check the speaker.