London, Jan 05 (Agencies): Travelling in a convertible with its top down? Think again, as it might expose you to dangerous noise levels, reveals a new study.

At 75 mph, levels recorded were as high as 100 decibels which could lead to damage to hearing if exposed for long periods. Even at 55 mph, levels were above 85 decibels which is equally damaging.

Researchers from the Saint Louis University School of Medicine, Missouri in the US, carried out tests on five cars including a Porsche, Saab, Nissan and Ford and recorded the noise levels at 55 mph and 75 mph.

They found that at lower speed, sound levels regularly exceeded 88 dB, the equivalent of a diesel train passing or a construction site. Road surface, other traffic, wind noise and driving speed - all contributed to the cacophony, the Journal of Laryngology and Otology reports.

At higher speed, it could be the equivalent of a jet plane passing overhead or a nightclub.

"We are recommending that drivers should be advised to drive with the top closed when travelling for extended periods of time at speeds exceeding 85.3 kmph (52 mph)," said Anthony Mikulec from the St Louis University.