Comparison between road test, loudspeaker and headphones evaluations of the sound quality of automobiles (original) (raw)

IPA - A Subjective Assessment Method of Sound Quality of Car Sound Systems

The paper describes a new subjective evaluation method of the acoustical quality produced by a sound system inside a car compartment. The method produces a single rating number, called IPA (Index of Performance Acoustic), defined as a weighted average of the subjective responses to a questionnaire, being compiled during listening tests conducted with the subject seating inside different cars. The paper describes the details of the subjective test, and focuses on the choice of questions in the questionnaire and of the weight to be employed. The principal innovation of the new method is the fact that the weights are changed according to the reliability of the subject (which is also inferred from the questionnaires), and thus the evaluation is very robust and almost immune from the inclusion in the panel of completely unreliable evaluators.

The Design of Automotive Acoustic Environments: Using Subjective Methods to Improve Engine Sound Quality

Proceedings of the Human Factors Society Annual Meeting, 1992

The sensory environment of the vehicle is an area where customer expectations have greatly increased in recent years. For example, sound quality has become a very important factor in determining customer perception of vehicle quality and value. In this paper, a method for evaluating sound quality is presented and used in an engine design application. As part of the design of a future midsize vehicle, 14 engine component modifications were being considered as ways to improve sound quality. A subjective evaluation was carried out to determine if these modifications had any effect on perceived sound quality and, if so, which modifications provided the greatest sound quality benefit. A paired comparison method was used in which subjects judged, first, similarity and, then, preference. The similarity results showed that the vehicle sounds were indeed perceived quite differently. Additional analysis, using multidimensional scaling, revealed that most of these differences could be attribut...

Evaluation and Noise Impact of Car Audio Systems

This paper presents the effects of, and the problems caused by, high-end audio systems used in passenger cars. Two major aspects of the problem were investigated: first, what is the quality of the sound reproduction that can be achieved in the car interior, and how, and to what extent, car audio systems can contribute to the noise pollution of residential areas. Correspondingly, both the interior and the surrounding sound field of the test vehicles was investigated for various operating conditions of the car (including switched off engines), with three different kind of music pieces. In order to assess the environmental impact, the overall insertion loss of the car was measured. Standard bypass measurements were also performed to demonstrate the difference in sound levels between a standard car audio and a car equipped with a high-end audio system.. For better illustration of the growing problem, we calculated noise maps for a peaceful holiday resort too. The results have shown that currently used highend audio systems are not really appropriate for good quality sound reproduction, caused both by disadvantageous acoustic characteristics of the cavity and artificially modified transfer characteristics of the electro acoustic system. Significant exterior sound level differences were found between different audio systems, ranging up to 20 dB. Exterior noise predictions have shown that high-end systems can significantly deteriorate the noise environment, especially for quiet places in the night period.

Quality Measurement and Evaluation of Vehicle Audio Systems

2000

This paper presents a new integrated set of software tools for obtaining both objective and subjective evaluations of car audio systems using a single session of recording with a mannequin in the cockpit. This system can be an important aid for the design of more effective car audio systems, especially loudspeaker subsystems. The tools implement a fully automated stimulation, acquisition

Effects of the Background Noise on the Perceived Quality of Car Audio Systems

2002

The paper describes the recording/reproduction technique and the subjective listening experiment aimed to the assessment of the effect of the background noise on the perceived quality of the sound being reproduced inside a car. The noise inside 3 different cars was recorded at various speeds both with a binaural microphone and with a Soundfield microphone. These background noise recordings are reproduced inside a special listening room, by means of a very sophisticated reproduction chain, designed so that at the ears of the listeners the same sound pressure is presented as inside the original car. A computer-based system is finally employed for collecting subjective responses to sound stimula, constituted by the reproduction of music or speech on an automotive sound system in presence of the background noise.

Subjective comparison of different car audio systems by the auralization technique

1997

This paper reports the results of a subjective evaluation experiment, based on the collection of questionnaires compiled by volunteers after listening to sound fields reconstructed by the auralization technique. Each synthetic sound field included both the car's interior noise and the transfer function of the sound system coupled with the passenger's compartment.

Sound quality evaluation of electric cars : preferences and influence of the test environment

2011

Many are the upcoming noise, vibration and harshness (NVH) challenges regarding electric vehicles (EV), not least due to absence of the masking combustion engine noise. In general, sound and vibration levels in the car's interior are significantly lower for EV's. However, tonal sounds caused by electromagnetic forces in the electric motor are in varying degrees present and provide audible feedback of operation during driving. The key question for how to target these sounds is to gain an understanding about what sound quality means for EV's. As an initial study, investigations were carried out to determine how the test environment influences the evaluation of the sound perception in an EV. Headphone evaluation with playback of binaural head recordings in both listening lab and a vehicle demonstrator "sound car" were compared to the real perception in a production-like electric car. A modified established scorecard for internal combustion engine (ICE) powertrain ...

Evaluating different vehicle audio environments through a novel software-based system

2004

An original software-based system, featuring two different tools, is here proposed for vehicle audio quality assessment. The first one performs the acquisition of relevant data for system modelling and for cancelling the undesired effects of the acquisition chain. The second offers a user-friendly interface for real time simulation of different car audio systems and for both objective and subjective evaluation, where the listening procedure is directly experienced at PC workplace. The validity of this approach has been examined through a subjective listening test set (more than 50 participants and three cars involved), developed by means of a dedicated software environment and based on appropriate ITU recommendations. Experimental results have shown that the quality rating delivered by conventional in-car procedure is confirmed when the software-based approach is used.

Industry-oriented software-based system for quality evaluation of vehicle audio environments

IEEE Transactions on Industrial Electronics, 2000

A new set of integrated software tools are proposed for the evaluation of vehicle audio quality for industrial purposes, taking advantage of the auralization approach that allows to simulate the binaural listening experience outside the cockpit. Two main cooperating tools are implemented. The first fulfills the function of acquiring relevant data for system modeling and for canceling the undesired effects of the acquisition chain. The second offers a user-friendly interface for real-time simulation of different car audio systems and the consequent evaluation of both objective and subjective performances. In the latter case, the listening procedure is directly experienced at the PC workplace, leading to a significant simplification of the audio-quality assessing task for comparing the selected systems. Moreover, such kind of subjective evaluation allowed to validate the proposed approach through a complete set of experiments (developed by means of a dedicated software environment) based on appropriate ITU recommendations.

Wow, what car is that?: Perception of exterior vehicle sound quality

Noise Control Engineering Journal, 2003

Up until now most research and application in vehicle sound quality has been directed at describing interior vehicle sound quality. Even though the interior sound of a vehicle is a major component of the perceived sound quality, exterior sound is audible both to potential users and bystanders. It may be argued that interior vehicle sound quality is concerned with meeting the buyerʼs expectation, whereas exterior sound quality concerns a) attracting attention and positive responses of potential customers and b) minimizing negative responses in the general public. It may therefore be argued that optimizing exterior sound quality will benefit both consumers and the community. This article describes an approach to perceived exterior vehicle sound quality. To attain an understanding of exterior sound, we investigate both the semantic descriptions that are elicited when different exterior sounds are heard and specific situations (i.e. a given sound/vehicle in a given environment). Across different sounds and driving conditions we find four subjective dimensions: loudness/annoyance, perceived quality, low-frequency content, and temporal variations. This factor structure allows discriminating the sound quality of a variety of modern cars. In more specific tests we find that participants both discriminate between different vehicles and different environments (free field conditions, urban driving conditions as well as different street shapes). These results indicate that designing and predicting exterior sound quality is a multidimensional task that requires different approaches than those traditionally used for interior sound quality.