Perception of rolling noise

• Due to improvements on combustion-engines and electric-engines for cars, tyre noisehas become the prominent noise source at low and medium speeds. Models existthat simulate the noise produced by a rolling tyre, as do models that auralize differenttraffic situations from a basic data set. When constructing a tyre it is of interestif improvements and planned changes are not only physically measurable, but thatthey also can be perceived. Focussing on that, two aims were followed in this thesis.The first aim was to combine an established model for tyre noise (SPERoN) withan auralization tool. The combined model can predict the spectrum of the soundat 7.5 m, as well as reproduce the sound for a given listener position. The auralizationuses a methodology where recorded sounds are converted to source signalsfor engine and tyre/road-interaction. These can be shaped by the spectra estimatedin SPERoN and synthesized back into a pass-by signal. Psychoacoustic judgementswere used to compare the modelled signals with recorded signals. To see how well themodelled signals match the real recorded signals for perception, two listening-testswere performed. The simulated and recorded signals were rated by pleasantness,loudness, roughness and sharpness using semantic differentials. It was found thatresponses for simulated and recorded signals correlate for all cases, but rankingscould not be reproduced exactly. The model can be further improved to be moreapplicable for listening tests. The model has been optimized after a first validation.The second aim laid focus on the perception of tyre/road noise. When designingtyre sounds, the main aim should be to increase the pleasantness of the total vehiclesound while maintaining the carried information and reducing the sound level. Tobe able to do this an understanding of how physical changes in a tyre are reflected inthe perception of the same tyre is essential. Thus, the second aim was to see if therolling noise of a tyre can be both differentiated and characterized by its perceptualqualities. The focus is on the perception of the sound outside the car, perceived byfor example a pedestrian. Listeners have judged different road tyre combinationsand their perception in terms of their emotional responses (pleasantness, activationand stress) and their psychoacoustic responses (loudness, sharpness, roughness, andpitch). The results confirmed that rolling noise can be perceptually differentiated. Itis further possible to differentiate between the effects of the street and the effects ofthe tyre on all emotional and most psychoacoustic parameters. The results suggestthat changes to road surfaces or tyres can affect both emotional and psychoacousticperceptual qualities.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

Nyckelord

Auralization

Rolling Noise

Perception

Tyre/Road Noise

Psychoacoustics

Publikations- och innehållstyp

lic (ämneskategori)

vet (ämneskategori)