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In a recent paper [Acta Acustica united with Acustica 93 (2007) 73―83] [1], an experimental noise annoyance meter was proposed for estimating acceptable noise levels, L Aeq7 . In this experiment, the subjects were able to relate the value of L AeqT to the differences between the seven-point annoyance scale scores displayed. Therefore, they directly gave the value of L AeqT for their acceptable threshold. This study investigated whether each acceptable L Ae q T level can be predicted from the annoyance and noise sensitivity. First, multiple regression models for each outdoor noise source were constructed to predict the annoyance from L Ae q T and the noise sensitivity based on the data collected in and around the city of Nagano. The regression models were used to determine whether each outdoor noise was over or under the acceptable threshold, which was defined as the midpoint between the scores "a little annoying" and "somewhat annoying." The correlation between the experimental results using a separate sample of residents from other prefectural capital cities in Japan and the predictions by the regression models was 0.703. Also, the discriminant models were used to classify cases by their values of a categorical dependent, where correlation with the proposed models was 0.837, indicating that the discriminant models are valid.

This paper describes a full vector intensity probe which advances the field of sound intensity and sound source direction estimation using six matched rotating and variable directional microphones. The probe has three pairs of microphones at an equal spacing of 30 mm that are set up in each of the x, y, and z directions and share the same observation point. The calibration method using the rotating microphone system is effective to correct position errors in the y- and z-axes microphone pairs. Sound intensity measurements using the variable directional microphone method can locate with accuracy a sound source, i.e., the structure parts radiating most acoustic energy. The system can find the maximum sound intensity level and beamwidth of the major lobe, and the peak sound intensity levels of the minor lobes. Therefore, a procedure for sound power determination based on minimum measurement data is theoretically and experimentally discussed. Consequently, it is possible to reconstruct only parts of the system emitting the most noise and measure efficiently the sound power level.

The present study extends our previous work [Furihata et al., J. Acoust. Soc. Am. 114, 174-184 (2003)] by investigating our electrodynamic planar loudspeaker when driven by a 12 bit digital signal with noise shaping. Changing the structure of the loudspeaker can lead to improvement, but in this paper improvements that can be made using signal processing are investigated. Results show that the digital loudspeaker demonstrated good linearity over its 84 dB dynamic range from 40 Hz to 10 kHz. This shows that a 12 bit digital loudspeaker which is equivalent to a 16 bit one is possible.

A drumlike traditional Japanese instrument, the mokugyo, is experimentally discussed. First, the acoustic characteristics of 176 mokugyos with diameters ranging from 7.5 to 120 cm and three drumsticks were measured. Results show that (a) the sound spectra consist of two common peaks [F1 (Hz): first peak frequency, F2 (Hz): second peak frequency] close together, with an average ratio (F2/F1) of 1.15, and (b) a drumstick beating the mokugyo is translated into an impact force applied over a period of time from 1 to 6 ms related to the mass and stiffness of the material wrapped around the tip of the drumstick. Second, to evaluate the acoustic response of a mokugyo in the final tuning process, the mechanical and acoustical analogy between the mokugyo and a bass reflex loudspeaker is theoretically and experimentally discussed. Results show that the model can be estimated within a relative error of 0.52% from the mass of wood chips. Finally, from a psychological experiment, the timbre of the mokugyo shows higher scores on psychological scales' when the ratio (F2/F1) becomes 1.15.

In this paper, an electrodynamic planar loudspeaker driven by a digital signal is experimentally discussed. The digital loudspeaker consists of 22 voice coils, 11 permanent magnets, a diaphragm with streamlined sections molded in plastic, and a suspension made of handmade Japanese paper between the diaphragm and the frame. First, the acoustic responses are affected by the arrangement of the voice coils, so an asymmetric arrangement is studied. This asymmetric arrangement is designed to obtain as flat a frequency response to an analog signal as possible. This arrangement is compared with a symmetric one and results show that the flatness of the frequency response around 1 kHz and 4 kHz is improved and that the sound reproduction band is from 40 Hz to 10 kHz. Second, to evaluate the acoustic responses to a digital signal, the digital loudspeaker is driven with a pulse code modulation signal. Results show that the digital loudspeaker can reproduce pure sound with a total harmonic distortion of less than 5% from 40 Hz to 10 kHz, exceeding this value only in a narrow frequency band near 4 kHz. This digital loudspeaker was demonstrated to have good linearity over its dynamic range of 84 dB.

The noise level and the effective noise level used for noise evaluation are physical indices and generally are not understood. It is believed that the understanding of such physical indices can be enhanced if one can realize a sound level meter which can display directly the relationship of the psychological effect by the noise with the measured decibel scale. From this point of view, this paper first evaluates in a laboratory experiment the relationship between the hue level expressing the psychological effect and the effective sound level. According to the obtained noiserating scale, the five-hue scale, “red, purple, yellow, green, blue” and the effective noise level correlate well. Next, a new sound level meter including the obtained noise-rating scale (to be called the hue sound level meter) and the existing sound level meter displaying only the measured value were compared at the actual measurement site. From the comparison, it was found that the hue sound level meter has better visual display and the display represents the auditory sense. From the foregoing results, it is possible to promote general understanding of the physical index.

Annoyance to noise is probably a good measure of the potential for complaint and community action. Each individual's degree of annoyance to noise cannot be accurately predicted from conventional laboratory studies and social surveys. Therefore, a logistic prediction model for individual allowable noise levels has been developed. In a previous paper [K. Furihata et al., Acta Acust. Acust. 93, 73-83 (2007)], an annoyance scale using the most frequently used annoyance ratings related to noise for community noise assessment in Japan was constructed. The dose-response relationships were obtained by actually listening to sounds in a field situation (1474 subjects) carried out at 14 metropolitan cities in Japan. The logistic prediction model was developed using the logistic regression parameters estimated from each cumulative percentage curve of seven annoyance scale scores based on all data (n=2940). To verify the hypothesis, individual relationships between annoyance and L(Aeq, (5 min)) for 24 normal-hearing subjects were constructed using a laboratory experiment. The main conclusion drawn from the results is that if at least one dose-response relation is obtained from each subject, the model can predict whether a sound is annoying or not from its L(Aeq,(5 min)) value. Moreover, validation of the model is needed in a field situation.

In addition to reporting the results of measurements of existing environmental noise and the results of calculations of noise from projected activities, the application of color for representing in terms of noise zones may be useful (ISO 1996‐2). Between color and noise, in spite of differences, there exists an interaction, although the connection between the visible and the audible expression is subjective. Subjectivity can in a given moment become objective, if one succeeds in unifying the visible and the audible. In the case of colored paper on a white background, the relation between the hue level expressing the psychological effect (annoyance) and LAeq(5min) (dB) of typical noise sources was discussed in a laboratory experiment. According to the obtained noise‐rating scale, the seven‐hue scale and LAeq(5min) are correlated well (r=0.874) as follows: white (value V9; not at all bothersome) ⇔ below 26 dB, light blue (hue 2.5B, value 8/chrome 4; not bothersome) ⇔ 26 to 37 dB, light green (2.5BG, 7/8; no...