Driving a Convertible Could Damage
a convertible with the top down
could expose you to dangerous noise
Levels as high as 100
decibels were recorded at speeds of
120 km/h which for long periods
could lead to damage to hearing.
Even at 88.5 km/h
levels were above 85dB, the
equivalent to a construction site.
Road surface, other
traffic, wind noise and driving
speed all contributed to the
Noise spikes – caused
by passing cars, trucks and
motorbikes added to the danger.
carried out tests on five cars
including a Porsche, Saab, Nissan
and Ford and recorded the noise
levels at 88.5 km/h and 120 km/h.
They found that at
the lower speed sound levels
regularly exceeded 88dB, the
equivalent of a diesel train passing
or a construction site.
At the higher speed
it could be the equivalent of a jet
plane passing over head or a
Exposure to noise
above 85dB for prolonged periods is
generally considered to damage
Not only was the mean
noise exposure excessive with the
top open, but the driver was also
exposed to extreme noise "spikes"
while driving on the highway – for
example, when driving next to a
motorcycle or lorry.
The study was
undertaken using a sound level meter
operated by a passenger in each car
The passenger took a
series of between eight to 10 sound
level measurements at various points
in the journey from the position of
the driver’s left ear, at various
During all data
collection, the car radio was turned
off, there was no conversation
between occupants, air conditioning
was turned off, the car horn was not
used and there was no rain or other
convertible cars may also be exposed
to additional noise when listening
to the car radio.
Even for comfortable
listening, the radio volume levels
required while driving under the
conditions assessed in this study
are likely to add significantly to
the noise exposure level.
During the study, no
excessive noise levels were recorded
from any tested car driven with the
top closed, meaning there is no more
than minimal risk of excessive noise
exposure when driving with the
convertible top closed.
Dr Anthony Mikulec
from the Saint Louis University
School of Medicine, Missouri, who
oversaw the study, said: “When the
convertible automobiles were driven
with the top open, high levels of
noise were consistently recorded.
"Although driving for
short distances under such levels of
noise exposure is unlikely to cause
a significant degree of
noise-induced hearing loss, our
study demonstrates that long
duration driving at high speeds with
the convertible top open will
increase the driver’s risk of
“In light of the
results of this study, we are
recommending that drivers be advised
to drive with the top closed when
travelling for extended periods of
time at speeds exceeding 85.3 km/h.”