Amanda Womac
Published  Jan. 11, 2011

When most of us hear the word “convertible,” we think wind in our hair and sun on our faces. However, a study published online Nov. 25, 2010, suggests we need to be thinking of one more thing: our hearing.

Researchers with the St. Louis University School of Medicine’s Department of Otolaryngology and the Ear Institute of Texas found that driving a convertible with the top down can increase the likelihood of hearing loss in drivers.

The study, published in England’s Journal of Laryngology and Otology, concludes that driving convertibles at speeds exceeding 55 mph with the top open may result in noise exposure levels exceeding recommended limits. The conclusion is especially true when driving for extended amounts of time.

Researchers used 85 decibels (dB) as the benchmark for their study because the National Institute for Occupational Safety and Health defined 85 dB as “excessive noise exposure.” Normal conversation occurs at about 60 dB. A lawnmower rings in at 90 dB and a chainsaw’s dB level is 110.

Researchers tested the decibel levels in the following vehicles at speeds of 55, 65 and 75 mph.:

• 2009 Saturn Sky Red Line

• 2004 Nissan 350Z

• 2001 Porsche 911 C4

• 2005 Saab Aero Convertible

• 2005 Ford Mustang GT

Researchers found it easy to hit 85 dB in a top-down convertible. However, the loudest car on their list was the 2009 Saturn Sky Red Line, which at 55 mph, was rated at 91 dB. At 65 mph, decibel levels were at 95.9 dB and at 75 mph, the car’s readings hit 98.7 dB, which the occupational safety agency recommends limiting exposure to 20 minutes.

For a more quite ride, the 2005 Ford Mustang GT fits the bill. This car was the quietest and recorded 82.4 dB at 55 mph. The 2004 Nissan 350Z produced the loudest peak sound, reaching 104 dB at 75 mph.

Overall, researchers discovered that mean noise exposure inflicted on the driver of a convertible car driven with the top open was 85.3 dB at 55 mph; 88.4 dB at 65 mph; and 89.9 dB at 75 mph. They warned that individuals in top-down convertibles are potentially at increased risk of noise-induced hearing loss and recommended that drives close the tops at speeds of 55 mph or greater.

The researchers rejected the use of noise-canceling earplugs or headphones because they might raise “safety and legal concerns” should the driver become less aware of emergency vehicles.

To read the study online, click here.