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An Assessment on the Sound Quality of the Car Audio System Using the Orthogonal Designs
Abstract
Audio tuning improves not only the sound quality of the car audio but also the quality of the completed car itself. However without the subjective assessment on the users' preferences, it is hard to tune the car audio satisfying them. Even though there are lots of factors to be considered to assess the preferences, only a restricted number of factors should be included in the experiment because the total number of experiments increases rapidly as the number of factors in the experiment increases. A large number of factors make it hard to explore the relationship between the sound quality and the sound characteristics and also makes the panels exhausted. In this paper, 8 sound characteristics, each with 2 levels, are considered for the experiment. An orthogonal design of experiment is suggested to reduce the number of experiments from 256 to 16. The analysis of variance is applied to show that Treble is the most significant characteristic of the reproduced sound of the given pop music. Also Deep Bass, SAD, and the interaction between Treble and SAD are found to be significant. For the given classic music, SAD is the only characteristic which turns out to be significant.
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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.
In this paper 'presence' (a sense of 'being there' in a mediated environment) is proposed as a global metric with which to evaluate audio displays that are part of advanced multi-modal media systems. An evaluation of different audio mixes using a self-report measure of presence, the ITC-Sense of Presence Inventory, and standard audio/visual quality evaluations is described. The results indicate that ratings of presence and audio/visual quality are enhanced by either the addition of bass or increase in volume. However, none of the ratings (with the exception of audio-related enjoyment) were elevated by increasing the number of audio channels. Our study demonstrates that presence is a useful quality metric that can be used in conjunction with more conventional audio measures to evaluate and optimize audio displays.
Perceptual differences between sound reproduction systems with multiple spatial dimensions have been investigated. Two blind studies were performed using system configurations involving 1-D, 2-D, and 3-D loudspeaker arrays. Various types of source material were used, ranging from urban soundscapes to musical passages. Experiment I consisted in collecting subjects' perceptions in a free-response format to identify relevant criteria for multi-dimensional spatial sound reproduction of complex auditory scenes by means of linguistic analysis. Experiment II utilized both free response and scale judgments for seven parameters derived form Experiment I. Results indicated a strong correlation between the source material (sound scene) and the subjective evaluation of the parameters, making the notion of an "optimal" reproduction method difficult for arbitrary source material.
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.
The perceived sound quality of high-fidelity loudspeakers was investigated by experimental procedures in three listening tests. Experienced listeners rated the sound quality using perceptual scales identified in earlier research (clarity, fullness, spaciousness, brightness versus dullness, softness versus sharpness, absence of extraneous sounds) and evaluation scales (fidelity, pleasantness). Ratings were also made regarding ideal reproductions. The results demonstrate the reliability and validity of the scales. Problems for continued research are discussed.
Spatial quality in reproduced sound is a subset of the broad topic of sound quality. In the past it has been studied less rigorously than other aspects of reproduced sound quality, leading to a lack of clarity in standard definitions of subjective attributes. Rigor in the physical measurement of sound signals should be matched by equal rigor in semantics relating to subjective evaluation. A scene-based paradigm for the description and assessment of spatial quality is described, which enables clear distinctions to be made between elements of a reproduced sound scene and will assist in the search for related physical parameters.
The experimental literature in sensory processes, perception, learning, and symbolic processes is evaluated within a theoretical interpretative framework, and attention is directed to needed further research. The coverage is selective as well as extensive, and a detailed description of critical experiments is given. Material on problems of synesthesia, human problem-solving, and language behavior is included. Controversial theoretical issues are discussed, and an attempt is made toward resolution of the behavioristic vs. gestalt issue wherever it appears. 1290-item bibliography and author index. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Perceived sound quality of loudspeakers, headphones, and hearing aids was investigated by multivariate techniques from experimental psychology with the purpose (a) to find out and interpret the meaning of relevant dimensions in perceived sound quality, (b) find out the positions of the investigated systems in these dimensions, (c) explore the relations between the perceptual dimensions and the physical characteristics of the systems, and (d) explore the relations between the perceptual dimensions and overall evaluations of the systems. The resulting dimensions were interpreted as "clearness/distinctness," "sharpness/hardness softness," "brightness-darkness," "fullness-thinness," "feeling of space," "nearness," "disturbing sounds," and "loudness." Their relations to physical variables were explored by studying the positions of the investigated systems in the respective dimensions. Their relations to overall evaluations were studied, and the implications of the investigations for continued research are discussed.
Three programs (female voice, jazz music, and pink noise) were reproduced using four different frequency responses and two different sound levels. Fourteen normal hearing subjects listened to the reproduction via earphones and judged the sound quality on seven perceptual scales (loudness, clarity, fullness, spaciousness, brightness, softness/gentleness, and nearness) and a fidelity scale. Significant differences among the reproductions appeared in all scales and could be attributed to the differences in frequency response or sound level or both. Interactions between the reproductions and the programs could be explained by the relations between the spectrum of the programs and the frequency responses used. The results for the noise program were similar to those for the jazz music program.
In two experiments two or three subject groups - 'listeners in general' (L), musicians (M), and 'hi fi subjects' (HF) - made evaluative ratings, similarity ratings, and verbal descriptions concerning different sound reproductions of certain music sections. The reliabilities of the ratings were in general high. Interactions between reproductions and music sections appeared, giving different ratings/rankings of reproductions at different music sections. Some differences in ratings between the L group and the other groups were suggested. Dimension analyses revealed some dimensions as 'distinctness,' 'brightness,' and 'loudness'. Other possible dimensions were suggested by the verbal descriptions.
Mean opinion score ratings of reproduced sound quality typically pool all contributing perceptual factors into a single rating of basic audio quality. In order to improve understanding of the trade-offs between selected sound quality degradations that might arise in systems for the delivery of high quality multichannel audio, it was necessary to evaluate the influence of timbral and spatial fidelity changes on basic audio quality grades. The relationship between listener ratings of degraded multichannel audio quality on one timbral and two spatial fidelity scales was exploited to predict basic audio quality ratings of the same material using a regression model. It was found that timbral fidelity ratings dominated but that spatial fidelity predicted a substantial proportion of the basic audio quality.
A study was conducted with the goal of quantifying auditory attributes that underlie listener preference for multichannel reproduced sound. Short musical excerpts were presented in mono, stereo, and several multichannel formats to a panel of 40 selected listeners. Scaling of auditory attributes, as well as overall preference, was based on consistency tests of binary paired-comparison judgments and on modeling the choice frequencies using probabilistic choice models. As a result, the preferences of nonexpert listeners could be measured reliably at a ratio scale level. Principal components derived from the quantified attributes predict overall preference well. The findings allow for some generalizations within musical program genres regarding the perception of and preference for certain spatial reproduction modes, but for limited generalizations across selections from different musical genres.
Loudspeaker measurement and their relationship of listener preferences: Part 2
- F Toole
- F Toole
Listening Test Methods for Automotive Sound Quality
- N C Otto
Perceived sound quality of high-fidelity loudspeakers
- A Gabrielsson
- B Lyndstrom
On the relative importance of spatial and timbral fidelities in judgments of degraded multichannel audio quality
- F Rumsey
- S Zieliski
- R Kassier
- S Bech