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What Animal Sound Does Not Make an Echo?

Everyone knows that a duck's quack does not echo. Or does it? This widespread myth can be swiftly debunked, because echoes don't depend on the animal, person or object creating the sound but on the environment in which the sound is produced. That is, there is no animal that produces a sound that can be guaranteed, 100 percent of the time, not to echo -- except, of course, for those animals that produce no sound.

The Science of Echoes
- An echo, simply put, is a reflection of sound. A "true echo" is a single repetition of the original sound, which is delayed by the limited speed of sound at 1,100 feet per second. Echoes result when sound waves encounter irregularities and then reverberate off of hard surfaces, such as rock walls, mountains or fences. Given the science of echoes, it soon becomes apparent that the contention that certain animal sounds cannot echo is completely untrue.
Myth of the Echo-Less Duck
- Like many popular myths and urban legends, the duck-quacks-don't-echo contention is of unknown origin. In the United Kingdom, professors at the University of Salford's Acoustics Research Centre conducted a 2003 study to put the myth to rest once and for all. By comparing the sound of a quacking duck in an anechoic chamber (a controlled environment where echoes cannot be produced) to a quacking duck in a reverberation chamber (where echoes are easily created), the research team concluded that duck quacks do, in fact, echo. However, the researchers did concede that the nature of a duck's quack -- with a long "aaack" sound at the end -- can tend to mask the echo, a fact that may have given rise to the myth in the first place.
Animals that Produce No Sound
- Though there are no echo-less sounds -- since any sound will echo given the right set of circumstances and environment -- there are animals that are guaranteed to produce no echo, since they don't make sounds in the first place. Rabbits are a good example. With few noise-making ways to communicate beyond a thump of their feet, rabbits are silent but friendly companion pets. Fish also don't make sounds that can be discerned by the human ear.
Animals that Rely on Echoes
- Echolocation is a biological sonar used most widely by bats, dolphins and toothed whales, although it also has been observed in shrews and certain cave-dwelling bird species. Echolocation involves the emission of an ultrasonic sound by the organism, with the specific goal of producing echoes. The animal can then compare the original sound emitted with its returning echoes to develop a detailed map of its surroundings. Echolocation also can be used by humans to gauge their immediate environs, as with blind people who tap canes, stomp their feet or make clicking noises with their mouths to observe how and when these sounds' echoes return.

Animals & Science