Volume 115, Issue 6, June 2004
Index of content:
- NOISE: ITS EFFECTS AND CONTROL 
115(2004); http://dx.doi.org/10.1121/1.1736654View Description Hide Description
Active control of the sound radiated from a piston set in a rigid sphere with a set of control point sources around is considered in this paper, where the scatteringsound field of the controlsound from the rigid sphere has been taken into account to minimize the total radiated sound power. Analytic results of the sound power are obtained and numerical simulations show that it is possible to reduce the radiation from a small piston set in a rigid sphere similar to the size of a human head up to a certain frequency. It is found that the introduction of the scattering object makes significant differences from the active control without scattering objects. This being the case, the scattering object makes the active noise control easier. To increase the global reduction of sound-power output, the optimal number and locations of the control sources and the optimal number and locations of error sensors are discussed. Finally, experiments with one control source and one error sensor around a head simulator have been carried out to verify the simulation results.
115(2004); http://dx.doi.org/10.1121/1.1652610View Description Hide Description
This paper describes the results of a large-scale questionnaire survey that ascertained children’s perceptions of their noise environment and the relationships of the children’s perceptions to objective measures of noise. Precision, specificity, and consistency of responding was established through the use of convergent measures. Two thousand and thirty-six children completed a questionnaire designed to tap (a) their ability to discriminate different classroom listening conditions; (b) the noise sources heard at home and at school; and (c) their annoyance by these noise sources. Teachers completed a questionnaire about the classroom noise sources. Children were able to discriminate between situations with varying amounts and types of noise. A hierarchy of annoying sound sources for the children was established. External levels were a significant factor in reported annoyance, whereas external and levels were a significant factor in determining whether or not children hear sound sources. Objective noise measures and accounted for 45% of the variance in children’s reporting of sounds in their school environment. The current study demonstrates that children can be sensitive judges of their noise environments and that the impact of different aspects of noise needs to be considered. Future work will need to specify the factors underlying the developmental changes and the physical and location dimensions that determine the school effects.
115(2004); http://dx.doi.org/10.1121/1.1719024View Description Hide Description
The majority of research on annoyance as an important impact of noise, odor, and other stressors on man, has regarded the person as a passive receptor. It was however recognized that this person is an active participant trying to alter a troubled person–environment relationship or to sustain a desirable one. Coping has to be incorporated. This is of particular importance in changing exposure situations. For large populations a lot of insight can be gained by looking at average effects only. To investigate changes in annoyance and effects of coping, the individual or small group has to be studied. Then it becomes imperative to recognize the inherent vagueness in perception and human behavior. Fortunately, tools have been developed over the past decades that allow doing this in a mathematically precise way. These tools are sometimes referred to by the common label: soft-computing, hence the title of this paper. This work revealed different styles of coping both by blind clustering and by (fuzzy) logical aggregation of different actions reported in a survey. The relationship between annoyance and the intensity of coping it generates was quantified after it was recognized that the possibility for coping is created by the presence of the stressor rather than the actual fact of coping. It was further proven that refinement of this relationship is possible if a person can be identified as a coper. This personal factor can be extracted from a known reaction to one stressor and be used for predicting coping intensity and style in another situation. The effect of coping on a perceived change in annoyance is quantified by a set of fuzzy linguistic rules. This closes the loop that is responsible for at least some of the dynamics of the response to a stressor. This work thus provides all essential building blocks for designing models for annoyance in changing environments.