This has been demonstrated by Anders Genell in his PhD dissertation at the Division of Applied Acoustics at Chalmers. He has carried out a series of tests using a model truck cab, where the subjects are exposed to different sound images and sometimes vibrations in the steering wheel and floor. The emotional reactions were examined using two test groups – experienced truck drivers and students.
“The subjects were asked to state how positive or negative and how calm or stressed they felt,” explains Anders Genell. It emerged that the students regarded the sound as being mostly noise whilst the drivers regarded certain parts of the sound as positive as it provided them with information.”
Taking into account the experience of the test subjects and the information content of the sound is a new approach when it comes to evaluating sound in a truck cab. Anders Genell has been an industrial PhD student at Volvo Trucks, and he wants to develop his know-how in this field.
“In the past the basic assumption has been that all sound is noise and the aim has been to reduce the peaks in the sound image. But if no sound is prominent then all that remains is general noise-like sound which is of no use to the drivers.”
Examples of sound which the drivers want to hear is sound that indicates when the engine is working as it should when under pressure, such as on an incline or when accelerating. In addition, they want a discreet engine sound in order to be able to listen to talking books or music. They also want some sound from the tyres on the road surface, which among other things provides them with information about how slippery it is.
The dissertation also shows that an overall approach to sound and vibrations must be taken in order to create a good working environment. If you influence one of the sources of sound or vibration then the perception of all the others is changed.
The abstract of the dissertation “Perception of Sound and Vibration in Heavy Trucks”: