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Dolphins almost constantly emit either clicking sounds or whistles. The clicks are short pulses of about 300 sounds per second, emitted from a mechanism located just below the blowhole. They are used for the echolocation of objects and are resonated forward by the so-called oily melon, which is located above the forehead and acts as an acoustic lens. The returning echoes are then picked up by the bony forehead, which acts as a reflector. This echolocation system, similar to that of a bat, enables the dolphin to navigate among its companions and larger objects and to detect fish, squid, and even small shrimp. The whistles are single-toned squeals that come from deeper in the larynx. They are used to communicate alarm, sexual excitement, and perhaps other emotional states. Because of the ability of dolphins to learn and perform complex tasks in captivity, their continuous communications with one another, and their ability, through training, to approximate the sounds of a few human words, some investigators have suggested that the animals might be capable of learning a true language and communicating with humans. Most authorities, however, agree that although the dolphin¡¯s problem-solving abilities put the animal on an intelligence level close to that of primates, no evidence exists that dolphin communications approach the complexity of a true language.