Experiments on individual and combined effects of noise and vibration of low or moderate intensity were conducted concerning paired associates learning task. The experiments concerned randomly intermittent noise at 64, 74 and 79 dB (A)(re 20 μPa, peaks az) and continuous or intermittent vibration at 66 and 76 dB (re 10^-5 m/s², vertical wholebody sinusoidal in 5 Hz). The learning task was evaluated by error rates in mean and standard deviation for each condition of noise and vibration. Subjective ratings of disturbance by noise and vibration were also made after the task. Sixty-four and 79 dB (A) noise produced detrimental effects on the learning. Seventy-nine dB (A) noise added with the continuous vibration indicated elimination of the effects of noise and vibration alone. Further, high disturbance did not always accompany high error rates in mean or standard deviation.

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Sound propagation over ground from a point source having a typical spectrum of motor vehicle noise was investigated by a computational study using theoretical models. Employing new parameters of an average propagation height and a classified resistivity of ground surface, a practical expression to estimate A-weighted excess attenuation was obtained with some charts for various source and receiver locations. Results of field and scale model experiment show a good agreement with the values estimated from this practical model. It is applicable to predict the sound levels of road traffic noise propagating over the ground with a typical acoustic impedance.

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It is not easy to observe the original spectrum information of a moving sound source because of the Doppler effect. Previously, we proposed the method to compensate the Doppler effect to obtain the original spectrum, which is realized by compensating the propagation delay. This method requires the orbit information of target sound source to derive the propagation delay. This paper describes the method to estimate the orbit of moving sound source using sensor array. Proposed method is composed of two parts; the position estimation using a pair of relative propagation delays which are derived from the cross-correlation function, and the orbit estimation by dynamical filtering using the Kalman filter. Simple simulation was carried out to evaluate the performance of the proposed method. The result shows the sufficient accuracy of estimation both of orbit and spectrum.

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As a basic study for the method of assessing the loudness of impulsive sounds, two stages of loudness matching tests were carried out using exponentially decaying isolated impulsive sounds with narrow frequency components by changing the decaying timeconstant and carrier frequency. As a result, it was found that the total energy (the squareintegrated value of sound pressure) should be evaluated to uniformly assess the loudness of isolated impulsive sounds over a wide range of decaying characteristic. To examine the influence of waveform of impulsive sounds on the loudness in detail, another experiment was made by using eight impulsive sounds with 1 kHz carrier frequency and various waveforms. Consequently, it was found that the variation of waveform is not so significant (only 2 dB at the most) for the loudness assessment.

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