The importance of protection of the global environment is reviewed and discussed from the following viewpoints which concern noise problems.(1) The relation between cost and benefit to prevent environmental pollution.(2) Noise protection without consump tion of energy and resources.(3) The definition of noise in art and in daily life s-ituations.(4) The necessity of noise rating for individual conditions.(5) The importance of composite noise rating methods.
Some of the soundscape studies conducted in Japan are reviewed. The concept of soundscape, being introduced into Japan, gave an impact on the methodology of en vironmental acoustics on which conventional researchers in the field of noise contro-lengineers relied on, and forced them to reconstruct the philosophy and methodology of their studies. Several field works have been conducted in Kanda, Kyoto and Fukuoka based on different ideas the workers have about the concept of soundscape and the research methodology. Some musicologists and sociologists have published books and papers describing and discussing on the cultural and sociological aspects of sounds in everyday life referring the concept of soundscape.
Evaluation of sound environments is a multifactorial task, comprizing measurement of both physical (acoustic) and auditory (psychoacoustic) quantities. Physical quantities are measured by physical methods, such offering the advantage that objective results can in general be achieved with less effort than in the case of auditory measurement, where listening tests are mandatory. Aurally-Adequate Sound-Measuring Technology (AASMT) aims at estimating auditory quantities from the results of physical measure ments. In this context, Binaural Technology in the form of artificial heads and -binaural signal-processing is extensively applied. It is expected that more and more measure ment and analysis tasks in sound-environment evaluation which could hitherto - only be performed via listening test, will adequatly be dealt with AASMT-in many cases even more effectively. Nevertheless, listening test will not become obsolete. Sound-environ ment evaluation will continue to rely on them, especially, when cognitive- factors come into play. In the light of the complex parallelity of physical and psychoacoustical factors in sound-environment evaluation and the ever growing demands of society with regard to the quality of the environment, the authors ask the question of whether a new type of expert may evolve-the sound/noise manager-or whether teams of experts with different backgrounds (noise engineer, sound designers) will have to be formed to comply with future demands.
(1) Irrelevant between-signal variation in the fundamental frequency of complex tones was introduced into discrimination tests of relevant within-signal frequency differences.(2) Correspondingly, irrelevant within-signal variation in the fundamental frequency of complex tones was introduced into discrimination tests of relevant between-signal frequency differences. The effect of (2) was substantially larger than that of (1). These results suggests a relative primacy of within-signal processing over between-signal processing for the discrimination of the fundamental frequency of complex tones.
In recent years, the attempt to evaluate the acoustic environment using the flucutua-tion characteristic (power spectral density of fluctuation) has been attracting attention. This paper introduces examples of fluctuation measurement aimed at environment evaluation and examines various problems related to fluctuation characteristic measure-ment of audio signals. Also, the function and composition of a special measurement system for measurement of the “fluctuation characteristic” the fluctuation analyzer, are described in the last part of the text. The authors have begun developing this sys-tem recently with the aim of supporting these studies.
This paper reviews the process of noise control in Japan. First, a short history of noise problems after World War II is mentioned. The decade of 1960's was a period of rapid industrial progress in Japan, and noise was recognized as one of the serious pollutants. Environmental standards for various noises were promulgated in series. Several noise control measures are described concerning technical aspects and enforcement of the noise policy. Finally, the complicated problem on evaluation of various noises is discussed by comparing results of social surveys performed in Japan and in foreign countries.
The sound environment reflects regional history and culture and life of people. And for developing and maintaining the region, the sound environment is also unignorable because of its regional originality. We took a survey on the present situation and transition of the sound environment to 136 answerers living in 8 residential areas of the City of Odawara, Kanagawa Prefecture. Main questions are “sound heard today, ” “sound used to be heard, ” and “sound representing Odawara.” Sound environment is increasingly unified because of the traffic noise caused by automobiles. Meanwhile, there are sounds indigenous to each residential area. Items chosen as “sound repre-senting Odawara” are “sound of festival, ” “sound of waves, ” and “sound of bells, ” and they are not necessarily such sound as is frequently heard in daily life, but inhabit-ants associate the sound with geographical and historic images of Odawara.
The word “soundscape” which was first proposed by Canadian composer R. M. Schafer is now very popular in world wide. In Japan several researchers are carrying on studies about the soundscapes. A survey was held with the purpose of applying the results to a design of a comfortable acoustic environment. The subjects were requested to give their preference to nineteen sorts of environmental sounds on a rating scale with seven categories of degree of “like-dislike” by own memory of the sounds. As the results of survey the sound sources were classified into four groups according to the degree of preference, and the conditions that the sound source should possess for soundscape were extracted. Thus the guide for the soundscape design is described as follows based on the results of survey and author's opinion. 1. The sound should not be so loud. 2. The sounds must have good tone qualities. 3. The sounds should be emitted at the most appropriate time and within a suitable duration. 4. The sounds should be matched with surroundings. 5. The sounds should be at least consented to residents of the neighborhood around the sounding position. The particular sounds of the soundscape or acoustic signals are generally emitted with some degree of intensity, however in some Japanese ceremonies there are no sounds at all as the performance within a particular area. Several examples of these ceremonies which are held in silence are introduced, and the author's opinion is that the most important thing in sound environment is the stillness, and that the basic concept of the soundscape design is the creation of the least quantity of sound by which the stillness is made more silent after accomplishment of the noise control.
In order to examine the method of estimating loudness on general noises in living en-vironments, two steps of subjective experiments were performed using artificial sounds. The results of Experiment 1 suggested that arithmetic average of sound pressure levels in octave bands is an appropriate loudness index for various kinds of sound with broad band spectra as well as the precise index such as the Loudness Level proposed by Zwicker. In order to further examine this fact, Experiment 2 was conducted using test sounds with discrete prominent spectral components. As a result, it has been clarified that the arithmetic average can no longer be applicable to such kinds of sound. In addition to these experimental studies, the relationships among representative noise indices were examined by numerical investigation on various sounds general in living environments. As a result, it has been confirmed that the arithmetic average of SPLs in octave bands from 125 Hz to 4kHz is highly correlated to Loudness Level by Zwicker for general sounds without tonal components.