Factors influencing the sound preference in urban open spaces

In this paper, based on a large scale survey in Europe and China as well as corresponding laboratory studies, the influencing factors on the sound preference evaluation, considering social, demographical, physical, behavioural and psychological facets, have been systematically examined based on statistical analyses for each of the 19 case study sites. Various sound types have been considered, including natural, human, mechanical and instrumental sounds. In terms of social/demographical factors, the results suggest that age and education level are two factors which universally influence the sound preference significantly, although the influence may vary with different types of urban open spaces and sounds. With increasing age or education level, people tend to prefer natural sounds and are more annoyed by mechanical sounds in general. It has also been found that gender, occupation and residence status generally would not influence the sound preference evaluation significantly, although gender has a rather strong influence for certain sound types such as bird sounds, especially at certain case study sites. In terms of physical factors (season, time of day), behavioural factors (frequency of coming to the site, reason for coming to the site), and psychological factors (site preference), generally speaking, their influence on the sound preference evaluation is insignificant, except for limited case study sites and certain sound types. The influence of home sound environment, in terms of sounds heard at home, on the sound preference has been found to be generally insignificant, except for certain sounds. It is noted that there are some correlations between social/demographical factors and the studied physical/behavioural/psychological factors, which should be taken into account when considering the influence of individual factors on sound preference.     

Dissimilarity and the Classification of Male Singing Voices

Traditionally, timbre has been defined as that perceptual attribute that differentiates two sounds when pitch and loudness are equal, and thus is a measure of dissimilarity. By such a definition, each voice possesses a set of timbres, and the ability to identify any voice or voice category across different pitch-loudness-vowel combinations must be due to an ability to "link" these timbres by abstracting the "timbre transformation," the manner in which timbre subtly changes across pitch and loudness for a specific voice or voice category. Using stimuli produced across the singing range by singers from different voice categories, this study sought to examine how timbre and pitch interact in the perception of dissimilarity in male singing voices. This study also investigated whether or not listener experience affects the perception of timbre as a function of pitch. The resulting multidimensional scaling (MDS) representations showed that for all stimuli and listeners, dimension 1 correlated with pitch, while dimension 2 correlated with spectral centroid and separated vocal stimuli into the categories baritone and tenor. Dimension 3 appeared highly idiosyncratic depending on the nature of the stimuli and on the experience of the listener. Inexperienced listeners appeared to rely more heavily on pitch in making dissimilarity judgments than did experienced listeners. The resulting MDS representations of dissimilarity across pitch provide a glimpse of the timbre transformation of voice categories across pitch.     

Dissimilarity and the Classification of Female Singing Voices: A Preliminary Study

Traditionally, timbre has been defined as that perceptual attribute that differentiates two sounds when pitch and loudness are equal and thus is a measure of dissimilarity. By such a definition, each voice possesses a set of timbres, and the identity of any voice or voice category across different pitch-loudness-vowel combinations must be due to an abstraction of the pattern of timbre transformation. Using stimuli produced across the singing range by singers from different voice categories, this study sought to examine how timbre and pitch interact in the perception of dissimilarity. This study also investigated whether listener experience affects the perception of timbre as a function of pitch. The resulting multidimensional scaling (MDS) representations showed that for all stimuli and listeners, dimension 1 correlated with pitch, whereas dimension 2 correlated with spectral centroid and separated vocal stimuli into the categories mezzo-soprano and soprano. Dimension 3 appeared highly idiosyncratic depending on the nature of the stimuli and on the experience of the listener. Inexperienced listeners appeared to rely more heavily on pitch in making dissimilarity judgments than did experienced listeners. The resulting MDS representations of dissimilarity across pitch provide a glimpse of the timbre transformation of voice categories across pitch.     

Can listeners hear who is singing? A comparison of three-note and six-note discrimination tasks

Timbre is typically investigated as a perceptual attribute that differentiates a sound source at one pitch and loudness. Yet the perceptual usefulness of timbre is that it allows the listener to recognize one sound source at different pitches. This paper investigated the ability of listeners to identify which pitch in an ascending or descending sequence of three or six stimuli was sung by a different singer. For three-note sequences, the task was extremely difficult, and with rare exceptions, listeners chose the most dissimilarly pitched stimulus as coming from the oddball singer. For six-note sequences, the detection of the oddball singer was much improved in spite of the added complexity of the task. These results support the idea that timbre should be understood as a transformation that connects the different sounds of one source and that a "rich" set of sounds is necessary to discover the trajectory.     

Perceived sound quality of sound-reproducing systems.

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.     

ANNOYANCE AND SPECTRAL CONTRAST ARE CUES FOR SIMILARITY AND PREFERENCE OF SOUNDS

Previous research has suggested that perceived similarity is based on primarily cognitive processes, whereas preferences are based to a larger extent on affective processes. This was put to an empirical test utilizing 15 complex sounds as stimuli and 25 subjects for the assessments. Various versions of multidimensional scaling were used as a method of comparison. The results show that data analyses must take into account individual differences in similarity and non-preference. Contrary to the hypothesis expressed, both similarity and non-preference were found to be based mainly on affective responses because a major proportion of the explained variance originated from the perceived annoyance of sound. This was not true for perceived loudness or for the acoustic variables of Zwicker's loudness and Aures' sharpness. Spectral contrast calculated as the number of maxima in the normalized Zwicker's specific loudness spectra was found to be the best acoustic candidate for explaining at the individual level what properties of sound cause them to be perceived as similar or non-preferred.     

Subjective evaluations of sound radiated by impacted plates, using the design of experiments method

This study combines physical and subjective approaches to evaluate the sound quality of impacted plates. A numerical model, based on the Hertz law of contact, has been used to determine the sound pressure level at any point in space resulting from an impact. Sounds synthesized using this model and those from experiments can then be exploited in a physical analysis and/or a subjective analysis of the effects associated with variations in parameters. Here the influence of certain physical parameters on the sound perception of impacted plates is evaluated through a design of experiments method and a subjective test of preference. The subjective test is based on an estimate of preference between two pairs of synthetic sounds by varying several structural parameters at the same time. This differs from other studies that vary only one parameter at a time and fix the other parameters.     

The use of multidimensional perceptual models in the selection of sonar echo features

The development of an accurate and efficient sonar-target classification system depends upon the identification of a set of signal features which may be used to discriminate important classes of signals. Feature selection can be facilitated through the identification of perceptual features used by human listeners in discriminating relevant sonar echoes. This study was conducted to establish a more reliable means of identifying perceptual features in terms of physical signal parameters as an initial step toward the development of an automatic sonar-target classification system. The results of an experiment involving eight subjects and six sonar echoes are presented. A model of the perceptual structure of these echoes was derived from subject similarity judgments using a multidimensional scaling (MDS) technique. It was found that three perceptual features accounted for the similarity judgments made by the human listeners. Echoes modified along candidate physical dimensions were employed to aid in the identification of perceptual dimensions in terms of physical signal parameters. The three perceptual features could be associated with signal parameters involving the amplitude envelope of the echoes.     

Design optimization of wide-band Tonpilz piezoelectric transducer with a bending piezoelectric disk on the radiation surface

There is a need for a model that identifies underlying dimensions of soundscape perception, and which may guide measurement and improvement of soundscape quality. With the purpose to develop such a model, a listening experiment was conducted. One hundred listeners measured 50 excerpts of binaural recordings of urban outdoor soundscapes on 116 attribute scales. The average attribute scale values were subjected to principal components analysis, resulting in three components: Pleasantness, eventfulness, and familiarity, explaining 50, 18 and 6% of the total variance, respectively. The principal-component scores were correlated with physical soundscape properties, including categories of dominant sounds and acoustic variables. Soundscape excerpts dominated by technological sounds were found to be unpleasant, whereas soundscape excerpts dominated by natural sounds were pleasant, and soundscape excerpts dominated by human sounds were eventful. These relationships remained after controlling for the overall soundscape loudness (Zwicker's N(10)), which shows that 'informational' properties are substantial contributors to the perception of soundscape. The proposed principal components model provides a framework for future soundscape research and practice. In particular, it suggests which basic dimensions are necessary to measure, how to measure them by a defined set of attribute scales, and how to promote high-quality soundscapes.     

Quality and loudness judgments for music subjected to compression limiting

Dynamic-range compression (DRC) is used in the music industry to maximize loudness. The amount of compression applied to commercial recordings has increased over time due to a motivating perspective that louder music is always preferred. In contrast to this viewpoint, artists and consumers have argued that using large amounts of DRC negatively affects the quality of music. However, little research evidence has supported the claims of either position. The present study investigated how DRC affects the perceived loudness and sound quality of recorded music. Rock and classical music samples were peak-normalized and then processed using different amounts of DRC. Normal-hearing listeners rated the processed and unprocessed samples on overall loudness, dynamic range, pleasantness, and preference, using a scaled paired-comparison procedure in two conditions: un-equalized, in which the loudness of the music samples varied, and loudness-equalized, in which loudness differences were minimized. Results indicated that a small amount of compression was preferred in the un-equalized condition, but the highest levels of compression were generally detrimental to quality, whether loudness was equalized or varied. These findings are contrary to the "louder is better" mentality in the music industry and suggest that more conservative use of DRC may be preferred for commercial music.     

The dependency of timbre on fundamental frequency

The dependency of the timbre of musical sounds on their fundamental frequency (F0) was examined in three experiments. In experiment I subjects compared the timbres of stimuli produced by a set of 12 musical instruments with equal F0, duration, and loudness. There were three sessions, each at a different F0. In experiment II the same stimuli were rearranged in pairs, each with the same difference in F0, and subjects had to ignore the constant difference in pitch. In experiment III, instruments were paired both with and without an F0 difference within the same session, and subjects had to ignore the variable differences in pitch. Experiment I yielded dissimilarity matrices that were similar at different F0's, suggesting that instruments kept their relative positions within timbre space. Experiment II found that subjects were able to ignore the salient pitch difference while rating timbre dissimilarity. Dissimilarity matrices were symmetrical, suggesting further that the absolute displacement of the set of instruments within timbre space was small. Experiment III extended this result to the case where the pitch difference varied from trial to trial. Multidimensional scaling (MDS) of dissimilarity scores produced solutions (timbre spaces) that varied little across conditions and experiments. MDS solutions were used to test the validity of signal-based predictors of timbre, and in particular their stability as a function of F0. Taken together, the results suggest that timbre differences are perceived independently from differences of pitch, at least for F0 differences smaller than an octave. Timbre differences can be measured between stimuli with different F0's.     

Towards standardization in soundscape preference assessment

The study of soundscapes involves diverse fields of practice, diverse approaches and diverse disciplinary interests. The field overlaps with the much larger and established field of environmental noise management, and also intersects, to various degrees, with other areas of acoustics such as sound quality, human acoustic comfort in buildings, and music—and also with non-acoustic fields such as wilderness and recreation management, urban and housing design, and landscape planning and management. Working Group 54 of ISO/TC 43/SC 1 has been formed with a remit of standardization for perceptual assessment of human sound preference (in outdoor space) using questionnaires. The working group began its work in 2009, with considerable and wide-ranging discussion amongst its members. This paper makes a range of observations, and sometimes suggestions, on matters pertinent to eventual definition of the soundscape; on outcomes of interest arising from experience of a soundscape; on the role of context in assessment; on sound sources in different places; and on relevant lessons for soundscape assessment from experience of questionnaire measurement of noise annoyance. It represents a personal view, though informed by a range of opinions from the Working Group meeting and from literature.     

空调压缩机噪声测试及其声品质客观参量分析*

针对空调压缩机辐射声场的不同场点噪声声品质的差异,采用心理学声品质参量即响度、尖锐度、总感觉噪度,对压缩机辐射声场的不同场点噪声进行声品质客观参量分析,研究压缩机场点噪声声品质客观参量值变化规律。通过特征响度研究各场点噪声响度在频域的分布,并得出压缩机各场点噪声特征响度峰值所在噪声频带。实验结果表明,对于处在压缩机不同方向上的场点,其噪声声品质客观参量值存在明显差异,但其噪声特征响度峰值却处在相同的噪声频带。研究工作为压缩机全方向降噪提供参考依据也为研究压缩机的噪声声品质探索了一种新思路。     

Manipulations of listeners' echo perception are reflected in event-related potentials

To gain information from complex auditory scenes, it is necessary to determine which of the many loudness, pitch, and timbre changes originate from a single source. Grouping sound into sources based on spatial information is complicated by reverberant energy bouncing off multiple surfaces and reaching the ears from directions other than the source's location. The ability to localize sounds despite these echoes has been explored with the precedence effect: Identical sounds presented from two locations with a short stimulus onset asynchrony (e.g., 1-5 ms) are perceived as a single source with a location dominated by the lead sound. Importantly, echo thresholds, the shortest onset asynchrony at which a listener reports hearing the lag sound as a separate source about half of the time, can be manipulated by presenting sound pairs in contexts. Event-related brain potentials elicited by physically identical sounds in contexts that resulted in listeners reporting either one or two sources were compared. Sound pairs perceived as two sources elicited a larger anterior negativity 100-250 ms after onset, previously termed the object-related negativity, and a larger posterior positivity 250-500 ms. These results indicate that the models of room acoustics listeners form based on recent experience with the spatiotemporal properties of sound modulate perceptual as well as later higher-level processing.     

Specification of component sound quality applied to automobile power windows

As cars become quieter the sound quality of components with electric motors becomes more important in the customer perception of vehicle quality. This has created a need to develop methods for the specification of component sounds. The objectives of this study were to identify perceptually important aspects, link them to acoustic metrics and, based on this, develop guidelines for the determination of requirements for power window sound. Seven prominent attributes were identified: dull, loud, annoying, steady, powerful, overall product quality and under-dimensioned. Effects of auditory stream segregation influenced the results. Power window sounds mainly consist of two sources: motor and window seal scratching. Subjects tended to judge only motor sound. Prediction models developed on isolated motor sound correlated well with judgements. Low loudness, sharpness and motor speed fluctuations led to perceived high product quality. The results emphasise the importance of handling auditory stream segregation and temporal variations in the sound design process.     

AFFECTIVE EVALUATIONS OF AND REACTIONS TO EXTERIOR AND INTERIOR VEHICLE AUDITORY QUALITY

Affective reactions to and evaluations of auditory stimuli are fundamental components of human perception. In three experiments, participants rated their affective reactions (how pleasant I feel) and preferences for these affective reactions (how much I like the way I feel) as well as affective evaluations (how pleasant the sound is) to interior and exterior binaurally recorded vehicle sounds varying in physical properties. Consistent with previous research, it was found that the orthogonal affect dimensions of valence (unpleasant-pleasant) and arousal or activation (deactivation-activation) discriminated between affective reactions induced by the different qualities of the sounds. Moreover, preference for affective reactions was related to both valence and activation. Affective evaluations (powerful-powerless/passive-active and unpleasant-pleasant) correlated significantly with affective reactions to the same sounds in both within-subjects and between-subjects designs. Standard sound quality metrics derived from the sounds correlated, however, poorly with the affective ratings of interior sounds and only moderately with affective ratings of exterior sounds. Taken together, the results suggest that affect is an important component in product auditory quality optimization.     

Temporal weights in the level discrimination of time-varying sounds

To determine how listeners weight different portions of the signal when integrating level information, they were presented with 1-s noise samples the levels of which randomly changed every 100 ms by repeatedly, and independently, drawing from a normal distribution. A given stimulus could be derived from one of two such distributions, a decibel apart, and listeners had to classify each sound as belonging to the "soft" or "loud" group. Subsequently, logistic regression analyses were used to determine to what extent each of the ten temporal segments contributed to the overall judgment. In Experiment 1, a nonoptimal weighting strategy was found that emphasized the beginning, and, to a lesser extent, the ending of the sounds. When listeners received trial-by-trial feedback, however, they approached equal weighting of all stimulus components. In Experiment 2, a spectral change was introduced in the middle of the stimulus sequence, changing from low-pass to high-pass noise, and vice versa. The temporal location of the stimulus change was strongly weighted, much as a new onset. These findings are not accounted for by current models of loudness or intensity discrimination, but are consistent with the idea that temporal weighting in loudness judgments is driven by salient events.     

基于平板冲击声的声源特性表征及自动识别*

以平板结构导纳函数为纽带,建立冲击声信号特征与声源特性之间的关联,获得与声源属性密切相关的特征用于目标分类。针对四边简支矩形被击板,借助信号参数识别算法获得与声源物理属性有关的6维导纳特征,并从冲击声样本中提取80维音色特征,将音色特征和导纳特征做相关性分析,获得与声源物理属性相关的信号特征集。利用BP神经网络进行分类,结果表明,当采用与特定声源物理属性相关的信号特征子集时,分类效果达到同组最优。