Perceptual differences in automotive acceleration sounds between drivers and passengers
Introduction
The acceleration sound inside a passenger car is one of the significant factors influencing the customer perception of the vehicle [1]. Therefore, most automotive researchers and engineers have put effort into improving sound quality as well as noise, vibration, and harshness (NVH) improvements in vehicles [2], [3], [4], [5], [6]. A variety of studies have been conducted on the sound quality of acceleration sounds. In particular, the subjective evaluation of the acceleration sound and the study of the relationship between acoustic parameters and affective attributes have been mainly conducted [7], [8], [9], [10], [11]. Moreover, the indexing of sound quality by quantifying subjective perception has also been a focus [12], [13], [14], [15].
Lee [15] presented the results of the objective evaluation of acceleration sound quality. A sound quality index for booming and rumbling sounds was developed based on an artificial neural network using the Zwicker parameter [16]. Moreover, the luxury sound quality index for a premium-class passenger car was proposed using multiple regression analysis [17]. Recently, Moon et al. [10] presented the affective dimensions for engine sound quality during acceleration. They derived a sound quality index for two affective attributes, refined and powerful, through subjective evaluations. They found that there were differences in the affective dimension and acoustic parameters between refined and powerful models. Interestingly, Moon et al.’s study noted that the affective adjectives related to refined and powerful differ from those of previous Kubo et al.’s results [8]. They found that nationality can affect the perception of acceleration sounds.
Several previous studies have been carried out to understand the perceptual difference of acceleration sounds by nationality. Noumura et al. [18] reported cross-cultural differences in the perception of vehicle interior sounds. They derived the perceptual characteristics of vehicle interior sounds through sensory evaluation. Subjective evaluation was conducted in the US, Germany, and Japan, and it was found that the preference of interior sounds, which can be expressed by two axes, luxury and sporty, were significantly different across cultures. In the case of Americans, 43 % of subjects preferred sportiness, and 57 % preferred luxury; for Japanese, it was 59 % sportiness and 41 % luxury, and for Germans, it was 86 % sportiness and 14 % luxury. Wagner et al. [19] presented the dimension of vehicle sound perception. They conducted an online survey about the requirement of quality of vehicle sounds for 1762 Germans and Americans. They derived the four attributes for high-quality sounds: roughness/sharpness, loudness, timbre/richness, and pitch/tonality. Moreover, they reported that the perceptual differences between Germans and Americans were significant concerning pitch. Thus, German customers preferred a less sharp sound than American customers. Kim et al. [20] proposed the target of the driving sound, operational sound, and electrical warning sound of a luxury sedan and investigated the regional preference of proposed sounds. The preference differences in vehicle sounds between Germans, Americans, and Koreans were reported through subjective evaluations. There was no significant difference in preference for idle and constant driving sound and operational sound by nationality. However, the engine sound during rapid acceleration and warning sounds, such as turn signals and seatbelt reminders, showed a significant difference in preference by nationality. Germans and Koreans preferred the refined engine sound to Americans, who preferred the more powerful sound. Moreover, it was found that Germans do not prefer electronic turn signal tones.
Furthermore, several studies [7], [21], [22], [23] have presented that perceptual differences can be caused by not only nationality but also individual prior experiences and expectations of acceleration sounds. Park and Kang [21] proposed the sportiness index of the acceleration sound by clustering the subjects according to their taste. They conducted a listening test for two groups divided by k-mean cluster analysis to derive a regression model for sportiness. They found that the acoustic parameters of the regression model were different between the two groups. Previously, Altinsoy [7] noted that customer tastes and expectations could play significant factors in judging the sound quality of vehicles. Altinsoy conducted a semantic differential experiment and interviewed to investigate the perception of the sportiness and pleasantness of the engine sound. His experiment noted that sportiness judgments are very similar between the two groups: one prefers luxury cars, and the other prefers sports cars. In contrast, pleasantness judgment showed a strong perceptual difference between the two groups. One group that prefers luxury cars considers the sporty sound very unpleasant, whereas the other group that prefers sports cars considers it very pleasant. Kim et al. [20] showed a correlation analysis between subjects to observe the individual differences in acceleration sounds. They conducted the subjective evaluation with 12 Germans, 11 Americans, and 12 Koreans. The correlation coefficient between the average and each score was calculated, and the average of the individual correlation coefficient was compared for each region. Correlation coefficients of 0.64, 0.66, and 0.51 for Germans, Americans, and Koreans, respectively, were derived. It was found that there is a significant difference in individual preference for acceleration sound. In summary, the perception of the acceleration sound may differ according to the nationality and preference of the evaluator.
Furthermore, previous studies [22], [23], [24] have reported that the color or styling of the vehicle and the driving experience affect the perception of the acceleration sound. Kubo [8] showed that the emotional properties of engine sound perceived by drivers differ according to driving conditions, such as constant speed driving and acceleration. For constant speed driving, attributes for pleasant and metallic were derived, whereas powerful, pleasant, and metallic attributes were derived for acceleration conditions.
As above, many studies on the difference in perception of acceleration sound according to nationality, driving situation, and the taste and past experiences of the user have been reported. Meanwhile, since the driver's and passenger's attention in driving will not be the same, the appreciation for acceleration sound will also differ. Thus, perceptual differences in acceleration sounds according to engagement in active driving or passive passenger situation can be expected. However, to our knowledge, it is not known whether auditory perceptions are the same when driving in person and when a passenger does not drive. Moreover, there is no literature focusing on the perceptual difference according to whether driving or not.
To address this unclear issue, this study aims to investigate the perceptual differences in the acceleration sound of a passenger car during rapid acceleration between drivers and passengers. For this purpose, we conducted a subjective evaluation of affective attributes for acceleration sounds such as annoyance, sportiness, acceleration feeling, and preference in driver and passenger situations by employing the multimodal simulator. The results presented in this study are an extension of our earlier work [25] in which we investigated the annoyance and sportiness perception of acceleration sounds by drivers and passengers. In [25], it was observed that there was a perceptual difference in annoyance and sportiness between drivers and passengers through the multimodal simulator-based test. However, the statistical analysis could not be conducted due to the small number of evaluators. Thus, statistical significance could not be confirmed. Therefore, in this study, perceptual differences were thoroughly analyzed from a statistical perspective by increasing the number of evaluators. Moreover, the additional attributes of the acceleration sound, such as acceleration feel and preference, were also evaluated. The rest of the paper is organized as follows. Section 2 describes the subjective evaluation employing a multimodal simulator. The results of the experiments are presented in Section 3. Section 4 presents the conclusions drawn from this study.
Section snippets
Equipment and experimental setup
To evaluate the influence of acceleration sounds during vehicle acceleration, a subjective evaluation in the actual vehicle environment has the advantage of evaluating the sound in a more realistic situation. However, it is difficult to provide the same acceleration sound to evaluators since it depends on the vehicle condition and the difference in the acceleration pattern. Moreover, such a difference in acceleration sounds can cause an error in the evaluation. Therefore, in this study, a
Experimental results and discussion
Fig. 9 shows the assessment results for the perception of annoyance, sportiness, feeling of acceleration, and preference with the mean and 95 % confidence interval (CI) plot. The blue circle indicates the results for the driver role, and the red triangle indicates the results for the passenger role. Since two experimental situations were evaluated for the same subjects, a paired-sample t-test can be used to statistically investigate perceptual differences in each experimental condition (EC)
Conclusions
In this study, we investigated the perceptual difference in the acceleration sound of a passenger car between drivers and passengers. For this purpose, multimodal simulator-based experiments were conducted. The subjective evaluation of affective attributes for the acceleration sound, such as annoyance, sportiness, acceleration feeling, and preference, was conducted according to the driver's and passenger's situation employing a multimodal reproducing system. Five experimental conditions were
CRediT authorship contribution statement
Seonghyeon Kim: Conceptualization, Methodology, Software, Validation, Investigation, Writing – original draft, Writing – review & editing. M. Ercan Altinsoy: Methodology, Project administration, Resources, Writing - original draft, Writing - review & editing.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
The authors would like to present their gratitude to all participants who participated in subjective evaluations. In addition, with special thanks to Herr Dipl.-Ing. Robert Rosenkranz for supporting the operation of the multimodal measurement laboratory. The authors would also like to give special thanks to Prof. Woojin Park from Seoul National University for discussing the mental model and perception of sound.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
References (31)
- et al.
Strategy and implementing techniques for the sound quality target of car interior noise during acceleration
Appl Acoust
(2021) - et al.
Sound quality improvement for a four-cylinder diesel engine by the block structure optimization
Appl Acoust
(2013) - et al.
Improvement of interior sound quality for passenger car based on optimization of sound pressure distribution in low frequency
Appl Acoust
(2018) - et al.
Sound quality evaluation of the booming sensation for passenger cars
Appl Acoust
(2009) - et al.
Model of psychoacoustic sportiness for vehicle interior sound: excluding loudness
Appl Acoust
(2018) Objective evaluation of interior sound quality in passenger cars during acceleration
J Sound Vib
(2008)- et al.
Dimensions of vehicle sounds perception
Appl Ergon
(2017) - et al.
A comparative study on subjective feeling of engine acceleration sound by automobile types
Int J Ind Ergon
(2019) Automotive sound quality-powertrain, road and wind noise
Sound Vib
(2009)- et al.
Improving diesel sound quality on engine level and vehicle level – a holistic approach