Relations between points of subjective equality (PSE) and L_<eq> for loudness, annoyance and endurance of road traffic noise exposed during the works were investigated, and effects of vibration on these subjective ratings of road traffic noise were also investigated. Eight male students were adopted as subjects. Road traffic noise(T) were exposed at 5 levels from 60 to 80 dBA, L_<eq>. Vibration was exposed vertically in whole body at 75 dB, VL (energy mean) overlapping road traffic noise at 4 levels from 65 to 80 dBA, L_<eq>(T(V)). Control experiments were also made using pink noise at 7 levels from 50 to 80 dBA, background noise of 42 dBA, L_<eq> and background noise of 58 dBA, L_<eq> in concomitance with vibration (P, B_0, B_1(V)). As a result of experiments, subjective ratings mentioned above had the linear relation with noise levels of T, T(V) and P respectively. Then, PSEs of traffic noise were calculated for these subjective ratings respectively. It was found that PSEs of loudness, annoyance and endurance of traffic noise were lower than L_<eq>. Vibration tended to affect to subjective ratings of road traffic noise in the lower levels. Further, present data were compared with those of experiments and community responses of other researchers.
This paper describes the stability of the pulse discharge sound source proposed in the previous paper for acoustical measurements. The sound source is ascertained to have stable characteristics which are necessary for acoustic measurements. And it is also ascertained that the power spectrum of the sound pulse has no zero point over wide frequency range. That is, the sound source can be used for the cross spectral estimation of transfer function. The measurement of acoustic field characteristics can be carried out in a usual room selecting the points of source and receiver, since the duration of a source signal is short and the reflected waves are easily removed using time window. The low signal to noise ratio due to low energy of the single signal is afraid, but the signal to noise ratio is much improved by the synchronous accumulation of many responses as waveform and the timing of pulse generation are quite stable.
Measurements of eivironmental noise all day long nearby residence are made by using L_<eq> meter which stores L_<eq1/6> for every ten minutes. 315 samples (i. e. one sample/km^2) are collected uniformly in Nagoya City during later half of '82. Associated informations around residence and reactions of inhabitants to noise environment are also obtained in this survey. The results are summarized as follows. 1. Average value of L_<eq24> was 60 dBA. Refering to average L_<eq> in daytime, those values in the morning(also in the evening) and in the night were lower by 4dBA and 9dBA respectively. 2. Residence in commercial area was exposed to higher level of noise by 5dBA comparing with residence in other area. 3. Influence of trunk roads on environmental noise was strong enough that the area nearby them exceeded the other area in noise exposure by 10dBA. 4. Reactions of inhabitants to environmental noise were found to become severe when L_<eq24> around residence exceeds 60dBA. Below 50dBA there seem little problems about noise.
An autoregressive and moving-average (ARMA) analysis of speech is described in this paper. For the estimation of ARMA parameters, both input and output of the model should be measured. But the analysis of speech can only observe speech; an output of the model, and the process of parameter estimation turns out nonlinear. We propose the method which estimates ARMA parameters and inputs simultaneously. The nonlinear problem in speech analysis can be reduced into two linear problems by this method. But the problems on both input and order estimation of the model may occur in this method. Some fundamentals of the input estimation are discussed. Two independent methods of estimations, the estimations based on pulse series input and Gaussian process input, are proved to be useful for speech analysis. Especially, it is shown that the accurate ARMA parameters can be estimated by using an assumption of pulse series input. On the order of the estimation model, the method is presented which analyzes the speech by a high-order model. The optimal model can be derived from this high-order model.
High-frequency acoustical pressure fields on a surface exicited by a line source located on the semicylindrical concave rigid wall are analyzed by three methods:1) acoustical ray and canonical integral representation, 2) acoustical ray and mode representation, and 3) near fields representation, with numerical evaluation results. Acoustical pressure fields in all of three representations expressed as functions of frequencies, cylinder radius, and distances between source and observation points can be represented in a universal and simple form. A simple relation to obtain acoustical pressure fields for any combination of frequency and radius from high-frequency acoustical pressure fields for a specific combination is derived. A hybrid ray-mode fields representation is deduced from the infinite ray series constructed by a ray tracing method and is discussed with error evaluation.
It is well-known that a time constant of measuring system sometimes produces a great effect on the observed value of the reverberation time of a room, especially when the room has a very short reverberation time. In this paper, a practical method is considered for evaluating and systematically eliminating this effect. More concretely, the above measuring system such as a sound level meter and a level recorder is regarded as a power observation system and then can be approximately treated as a first-order lag element. On the other hand, the reverberation characteristic of the diffused sound room can be also treated as another first-order lag element, according to a well-known Sabine's reverberating equation. At this time, an analytical expression for the actual reverberation process of this room is derived in an explicit form containing two time constants of the room and the measuring system. Based on this viewpoint, three types of estimation algorithms are proposed for actually estimating a true reverberation time of the room from the observed data of reverberation curve affected by the time constant of measuring system. Furthermore, the legitimacy of the present theory is experimentally confirmed by applying it to the actually observed data of reverberation curve.
A Michelson interferometer with an arm of flexible optical fiber has been proposed for the vibration amplitude measurement. If a micro lens is attached at the end of the fiber, the interferometer becomes more useful. Up to now only lenses which radiate a collimated laser light are used and the test objects used for the measurement are almost specular ones. The actual vibration objects are optically diffuse ones and it is not clear whether such a lens is best for diffuse objects or not. From the point of view optical fiber probes with a collimating and a focusing lenses are constructed. Using several test objects with various surface roughness, their performances are compared with each other. As the results the optical probe with a focusing lens is proved to be better for actual diffuse objects. This probe is successfully used also for the vibration amplitude measurement of a transducer in the water.