Keiji Kawai

Effect of room acoustics on musicians' performance. part I: Experimental investigation with a conceptual model

This study aimed to investigate the notion that musicians adjust their performance to suit the acoustics of concert halls. First, a schematic model was developed to provide a basis for the investigation. Second, a performance experiment was conducted: musicians performed under different acoustic conditions simulated in an anechoic room. The performances were recorded, and the musicians were interviewed about the technical details of the adjustments that they made to suit the acoustics. The results showed how expert musicians adapted their performances to the acoustics. Third, as a pilot study to examine if differences could be objectively identified, a listening test and acoustic analysis were conducted on a recorded violin performance. The study confirmed that differences could indeed be objectively identified, at least in terms of the tempo and extent of vibrato.

Introduction of sound material in living environment 2004 (SMILE 2004): A sound source database for educational and practical purposes

Sound sources are used in various settings of education, research, and business that are related to architectural acoustics. Especially in educational scenarios, they are very effective for students to learn theories together with the experience of listening to actual sounds related to them. Sound Material In Living Environment (SMILE 2004), a sound source database published in 2004 in DVD form (Japanese only), is the culmination of our project. SMILE 2004 is intended as a collection of sample sounds for use in lectures on architectural acoustics at universities or industrial high schools. In addition, it is useful for measurements or demonstrations for academic or practical purposes. The database contains 913 digital sound files of real sounds and impulse responses, which cover the study fields of acoustics, noise control, and soundscapes. Each sound is accompanied by such information as the 1/1 octave band sound pressure levels and a brief explanation and photographs of the situation in which the sound ...

Blending vocal music with a given sound field due to the characteristics of the running autocorrelation function of singing voices

This is a study to meet music and the opera house acoustics. It is said that singers adjust their interpretation style according to the acoustical condition of the sound field in a room. However, this mechanism of blending of musical performance with the sound field is unknown. In order to obtain a method of performance blending of opera house acoustics, we attempted to develop evaluation criteria for a singing voice in terms of the minimum value of the effective duration of the running autocorrelation function (r‐ACF), (te)min, of sound source signals. This temporal factor has shown to have close correlation with the subjective response of both listeners and performers to sound fields [Y. Ando, Architectural Acoustics (AIP Press/Springer‐Verlag, New York, 1998)]. As example for the control of (te)min due to performing style, effects of singing style, kind of vowel, relative pitch, vibrato extent, and intonation on the values of (te)min are demonstrated. In addition, the fine structure of the r‐ACF is dis...

Experimental measurements of word intelligibility of pre-school children under acoustic interferences of reverberation and background noise

Child day-care rooms require optimum acoustic condition as children from 0 to 5 years old are supposed to be vulnerable group against interferences with verbal communication by background noise and excessive reverberation. However such interferences on the children seem not to have been examined in the field of architectural acoustics. Thus on-site experiments were carried out to measure word intelligibility of children from 3 to 5 years old. The procedure was like a true or false game. Each of the test words was mixed with two or three levels of pink noise and convolved with the room impulse responses with different reverberation times. The words were presented to the children and control groups (elementary school pupils and college students) by a loudspeaker in a daycare room. They were asked to judge whether the word was food or not, and to raise their hands holding yes or no signs. The experiment was repeated three times in different daycare centers with revisions of the condition settings. As the res...

Experimental measurements of word intelligibility among pre-school children under differing conditions of reverberation and signal-noise ratio

Many children, from 0 to 5 years old, spend most of their active hours in child day-care centers. Rooms in these centers are often very noisy, due to both the voices of children or sounds of various activities and to the excessive reverberation attributable to the little use of sound-absorbing materials. Some researchers have studied the speech intelligibility of elementary school children, but we were unable to find those of pre-school children. Thus, in this study, an experiment was carried out a word intelligibility test on children from 3 to 5 years old in a classroom of a child day-care center. The procedure was like a game. Each of the presented words was mixed with pink noise at one of two S/N ratios, and convolved with the impulse responses of three reverberation times of 0.3, 0.9, and 1.8 s. Children were asked to judge whether the word was food or not, and to raise their hands holding yes or no signs. As a result, the correct answer ratio for 3-year-old children was lower than the ratio for othe...

Overview of acoustic environment of child daycare facilities in Japan: Current situation and recent researches

Demands for child daycare facilities are continuously increasing in Japan as the Japanese society is changing with respect to womens social advancement in the workforce. However, since there are virtually no guidelines for the acoustic design of daycare facilities in Japan, many daycare classrooms have been built without considering acoustics or sound insulation. As a result, the rooms tend to be too noisy and too reverberant for children in the process of language and listening acquisition. This is a report both on the present situation and architectural trend of daycare facilities and on the existing researches for the acoustic environment of daycare classrooms, aiming to share the information about daycare facilities in Japan for the discussions to develop guidelines of acoustic design.

Community response to transportation noises in Japan: Secondary analysis using the Japanese socio-acoustic survey data archive

A number of socio-acoustic surveys on community response to transportation noises have been carried out in Japan since 1970s. The findings from early precious surveys contributed to the establishment of Noise Regulation Law and Environmental Quality Standards regarding noises. However, micro datasets consisting of noise exposure and reactions to noise from recent studies have yet to be accumulated into a unified system. Dose-response relationships obtained through re-analysis of micro-data form the basis of the progress of effective noise policies. Thus, the Japanese Government faces many difficulties in reviewing noise policies. To develop an archive of community responses to noise, we established the Japanese Socio-Acoustic Survey Data Archive (J-SASDA) and have started the secondary analysis since 2011. In this presentation, we introduce the outcomes of our activity. First, we compare exposure-annoyance relationships among the modes of transportation using the J-SASDA and determine the curves per mode ...

Describing soundscape and its effects on people where soundscape is understood as an expansion of the concept of noise engineering

This study discusses how to describe sound environment and people in terms of ‘‘soundscape’’ as an expansion of the ‘‘noise engineering.’’ In the framework of the conventional study field of noise evaluation, typically, sound environments are represented by loudness‐based indices such as A‐weighted sound pressure levels, and the impact of sound environments on people is represented by annoyance response or some physiological metrics. In the case of soundscape studies, however, the description should be expanded beyond what has been used in noise engineering. This matter has already been frequently discussed, but it doesn’t seem that much consensus has been achieved concerning it yet. With respect to the effects of sound environment on people, since the concept of soundscape focuses on personal and social meanings of environmental sounds including the historical or aesthetic contexts, the effects are considered to be represented not by a singular concept such as comfortableness or quietness, but by multipl...