The theory of evolution has captivated many of the greatest brains the world has ever seen. But now scientists have given a truly priceless gift - to the lovers of dreadful puns.

In a move that will spawn endless cracks about "sole music", "piano tunas" and "salmon chanted evenings", Manchester University researchers have discovered that humans may have inherited their love of loud music from fish - no, not the former lead singer of Marillion.

They believe that the average bathroom singer or sporting event bawler is encouraged by the sacculus, part of the balance regulating vestibular system in the inner ear.

A report in New Scientist magazine says the sacculus is not thought to have any hearing function. Even more curiously, the saccular frequency sensitivity appears to mimic that of fish - the only creature known to use it for hearing. This suggests that the mechanism has been inherited by man from piscine ancestors.

When music is played loudly it seems to trigger, through the sacculus, the same part of the brain that produces powerful sensations associated with activities such as sex, hunger and bungee jumping.

After tests on about a dozen students, the scientists concluded that the human sacculus seems to respond to music at about 90 decibels upwards.

Loud rock and rap, if not sole (you were warned), music somehow adjusts the balance in the ears. Singing loudly in the bath has the same effect because inside the larynx a Motorhead-level of 130 decibels can be produced or, as the psychologist Neil Todd, who led the study, put it in technical terms: "It's bloody loud in there."

In the tests, the saccular sensitivity of students was found to range from 50 hertz to 1000 hertz, peaking at between 300 and 350 hertz. On a musical scale, middle C has a frequency of 261 hertz.

"The distribution of frequencies that are typical in rock concerts and at dance clubs almost seem designed to stimulate the sacculus," Mr. Todd said. "They are absolutely smack bang in this range of sensitivity."