Analyses of cortical continuous brain waves in relation to subjective preference of physical environments

Abstract

The living environment is composed of elements involving spatial and temporal factors.The spatial standards were frequently employed to design as knowledge, but the temporal standard was not clear, and there was few theory formally adopted pertinently. Nevertheless, the temporal factors are obviously concerned with activity in the left cerebral hemisphere, in accordance with physical environment changes. Here, it was objectively led this phenomenon further. For sound fields, four independent physical factors were prevailing for designing a sound field: (1) the initial time delay gap between the direct sound and the first reflection, tot1; (2) the subsequence reverberation time, Tsub; (3) the level of listening, LL; and (4) the magnitude of interaural cross-correlation (lACC). In particular, the first two factors have been composed of a standard of time. The subjective preference theory was effectively applied for the planning of a few music halls. As far as the temporal factors are concerned, the preference of sound fields can be calculated by autocorrelation function of sound source signal together with such temporal factors. But it is weakness for subjective evaluation in general living environments entirely obtained by questionnaire using "language". Therefore, a method for measuring a human being's brain responses to external sound stimuli was arranged. The aim of present study was to identify the relationship between the subjective preference and the brain responses corresponding to the temporal variation. The method applied here is to analyze the autocorrelation function of continuous brain waves (CBW) in the awave range and extend this relationship for a visual environment that trying to approach for all conditions. , Up to present, CBW were reported by the wave type or the frequency variation, it is inadequacy to observe following a variation of temporal occasion. The "effective duration" ("t e ) was defined by the effective gap of the initial deduction (0.1 envelope) of the autocorrelation function (ACF) in the a-wave range; it involves a 2.5 s linear integral sum to correspond well to the stimulation by considering "psychological present".Chapter I states an important theory of subjective judgement, a theory that gives us a concept of the relationship between subjective preference and the autocorrelation function of brain waves.Chapter II optimizes a stimulation system (paired-comparison system) and the analyses ofACF of brain waves in the a-wave range by changing the btl of a music sound field (Motif B: Arnold's Sinfornietta, Opus 48) to 35 ms and 245 ms. Results show that the effective duration ofACF ("t e ) of CBW in the a-wave range correlates well to the subjective preference in a 2.5 s segment corresponding to the "psychological present". Furthermore, the values of "t e in the a-wave range correspond efficiently to the subjective preference and prolongs when the preference score increases. The EEG channel T3 is a forcible recording for detecting the temporal variation in brain by comparing with T4...