Session: 01-02-01: General

Paper Number: 72907

Start Time: Tuesday, 11:05 AM

72907 - Research on Tone Quality for Vehicles Considering the Masking Effect 

The acoustic performance is one of the most competitive indices of automobile, but traditional sound pressure level is not able to reflect the hearing sensation of customer. So the sound quality (SQ) plays important role in the acoustic assessment. With the transformation of energy structure, electric motors and hybrid power unit are replacing the internal combustion engine as the driving force of car. Meanwhile, the masking effect of the internal combustion engine noise disappears, so the high frequency characteristics of tones is more prominent. Hence, it is of great significance to explore the influence of tones on the SQ for abnormal sound diagnosis and acoustical development.

Currently, there are some problems in the study of tone psychoacoustics: (1) Only the prominence of tones is concerned, and the relationship with subjective preference has not been constructed, which is difficult to determine the influence of tones on the SQ for vehicles. (2) No comprehensive consideration of the influence of tones in different frequency distribution on the SQ, while ignoring the differences in background noise inside the car on masking effect, and it is difficult to directly guide the abnormal sound diagnosis of vehicles. To address this issue, four different types of vehicles (bus, SUV, pure electric car, fuel cell heavy truck) were selected as the research object. The sound samples of the tested vehicles in various modes and working conditions were collected, the semantic differential (SD) and paired comparison (PC) were adopted to conduct the jury test. According to the subjective evaluation results, the specific samples were chosen for feature extraction, and the prominence ratio (PR) was determined as an effective evaluation index of tones on SQ. Then, the masking effect of the background noise was considered in different vehicles, taking the center frequency of the critical band as a reference, two typical working conditions were selected to add tones of different frequencies and energy. The influence of tones on subjective evaluation was explored from the two dimensions ("audible" and "irritable"), and obtained the PR limits of tones in different frequency bands. The results show that whether tones can be “audible” and “irritable” are related to the masking effect of background noise and the tone frequency distribution. The PR limit has great difference under various working conditions and operating modes, the specific results are as follows:(1) air conditioner (AC) ON at idle speed: PR>3, PR>7, PR>3 is audible and PR>7, PR>8, PR>6 is irritable when the tone frequency f<600Hz, 600Hz<f<2000Hz, f>2000Hz; (2) 90 km/h: PR>1 is audible, and PR=9 still does not feel annoying when the tone frequency f<600Hz, PR>6 and PR>2 is audible for 600Hz<f<2000Hz and f>2000Hz, PR>7 and PR>5 is irritable; (3) for f<600Hz, the energy in the frequency band is very large, so a smaller PR can also be heard. The reason why higher PR cannot cause irritability is that lower sensitivity of auditory system in this frequency band.

Presenting Author: Rui Zhang Tianjin Univeristy

Authors:

Jiewei Lin Tianjin University
Rui Zhang Tianjin Univeristy
Qidi Zhou Tianjin Univeristy
Junhong Zhang Tianjin University
Gengyi Lin Tianjin University