Morimoto(1989)在廳堂聲音空間印象(spatial impression) 研究中提出聆聽包被感(listening envelopment,LEV)與聲源寬廣度(apparent source width,ASW)兩種要素,是決定一般演奏會廳堂空間感的必要條件。而聲源寬廣度(ASW)的聲音印象通常由直達音與早期反射音來構成(Morimoto,1989)而包被感是由迴響元素來形成。 Ando(1985)所提出的舞台上的聲源訊號到聆聽者大腦構成的大腦聽覺路徑(auditory path),可以充分說明中樞神經系統是如何處理聽覺神經末梢區域形成的神經脈衝,我們可以依據從大腦皮質上的腦波反應來觀察神經處理聲音訊號過程的反應特徵進行歸納。本研究藉由改變空間之雙耳互函數級數(magnitude of interaural cross-correlation function,IACC),考察不同的室內聲源寬廣度(ASW)反應和大腦聽覺慢性頭頂反應(slow vertex response,SVR)受聲源刺激所產生之變化做逐一比較,並試著建立一個客觀的生理聲學設計方法。 研究結果發現:1. 在心理實驗中藉由改變雙耳互函數級數(IACC),聲源寬廣度的心理量化值之排序為:ASW(IACC=0.56)=0.45>ASW(IACC=0.68)=0.03>ASW(IACC=0.35)=-0.16>ASW(IACC=0.81)=-0.32;呈現非線性之關係。 2. 在腦波之變化比較結果發現ASW(-0.32)到ASW(0.45)之範圍間,隨著ASW增加腦波在A(P2-N2) 之振幅差將減少;而左腦N2之潛時會隨著ASW增加而縮短。
Morimoto (1989) proposed in a spatial impression study that listening envelopment (LEV) and apparent source width (ASW) were two essential components that determine the spatial sense of a concert hall. While the acoustic impression of ASW was usually composed of direct sound and first reflection (Morimoto, 1989), the LEV was formed by response element. The auditory path through which an acoustic signal from the stage was transmitted to the listener’s brain proposed by Ando (1985) demonstrated in detail how the central nervous system processes the nerve impulse formed in the auditory nerve ending. The characteristic response in the process during which the nerve processes the acoustic signals can be observed and summarized using the cerebral cortex brainwaves. By modifying the magnitude of interaural cross-correlation function (IACC) of the space, the study investigated the changes in different indoor ASW responses and slow vertex response (SVR) caused by apparent acoustic stimulation and compared the difference among these changes. The study also tried to construct a study method with an objective physiological acoustic design. According to the study result: 1. By modifying the IACC in the psychological experiment, quantitative psychological measurements of ASW were as follows: ASW(IACC=0.56) = 0.45 > ASW(IACC=0.68) = 0.03 > ASW(IACC=0.35) = -0.16 > ASW(IACC=0.81) = -0.32, demonstrating a non-linear relationship. 2. The comparison result between changes in brainwaves suggested that within the range from ASW(-0.32) to ASW(0.45), the difference in brainwave amplitude at A (P2-N2) decreased with the increased ASW; while the duration of N2 latency of the left hemisphere shortened with the increased ASW.