SAFETY ;
Sound science
In a sophisticated sound lab, engineers work to keep truck operators safe.
from heaters, fans, air conditioning
systems or refrigerators could pre-
vent the driver from sleeping sound-
ly. Drivers who are prevented from
sleeping well are seldom the safest or
most efficient on the road.
In the lab
At the sound lab at Volvo Trucks in
Göteborg, Sweden, noise can be test-
ed in a variety of ways. There are two
sound chambers for testing engine
noise, one for engine and transmis-
sion noise, an in-cab noise room, a
reverberation chamber, as well as the
vast main testing lab, where the noise
made by a complete truck can be mea-
EDITED BY DARREN CONSTANTINO
sured, using a simulated drive-by.
In the lab, tests are carried out using simula-
The work carried out at a truck sound lab is all about controlling noise levels. A truck driver experiences a variety of different sounds while working, some of which might be considered pleasant tions, where a computer registers and measures the decibel levels. In-cab noise is measured in its ears. The measurements are extremely accurate, according to Volvo. Real tests are
using an artificial head with microphones
but, for the most part, the work of the sound then performed on prototype trucks at Volvo
engineers focuses on keeping unwelcome noise Trucks’ proving ground outside Göteborg.
at a minimum. Volvo Trucks’ lets us have a look
“We started using simulations and artificial
behind the scene at its sophisticated sound lab. heads in the 1990s,” Bodlund recalled. “Now
Unlike many other areas relating to envi- we can carry out more tests in less time and
ronment and safety, research into noise is not obtain more detailed data. In addition to deci-
necessarily driven by legislation. The sound bels, we can also measure frequencies and sev-
levels inside a cab are already below the legal eral other aspects of the noise.”
limit for noise in the workplace. It’s more a
“In the lab we can separate different sounds,”
question of comfort and safety, said Kaj Bod- Keulemans said. “We can block everything else
lund, a senior technology specialist working and just measure and analyze the noise made
with product development on Volvo Trucks.
specifically by the engine, silencer or transmis-
“Low, monotonous sounds are known to sion system, for example.”
reduce brain activity,” added Christina Keule-
Since Bodlund began his work on noise at
mans, feature leader in-cab noise at Volvo Volvo Trucks almost 20 years ago, a great deal
Trucks. “The driver gets tired and, eventually, has happened. Back in the early 1990s, in-cab
risks falling asleep.”
noise levels of 74–75 dB were not uncommon.
The noise made by on-board systems can Today, they are down to a far more tolerable
also be disturbing for drivers, especially when 70 dB.
they are trying to sleep or rest. Excessive noise
“We realize that there will come a point
