A method of calculating the reverberation time of a room partitioned by curtains was derived after the Eyring's method on the acoustics of coupled rooms. The values of the calculated reverberation time by the present method show better agreement with observed values than those obtained by the well-known Sabine's formula.
Japanese vowels in 3-mora or 5-mora words and those in very short sentences were analyzed with Sonagraph. Standard values were decided for each formants of eack vowels. (Averages were calculated from the examples which were not influenced by preceding or subsequent consonants. ) Ones which were higher than the standard values were marked (+), ones lower than those values were marked (-), and ones which took same values were marked (0). Consequently, obvious tendencies were found when all the samples were grouped according to the kinds of consonants which have influence on vowels. There were insoluble questions about first formants of /e/ and /o/ followed by /N/, especially when they are occured in a speech.
When the telephone receiver is used for communication, the leakage path between the earpiece and the pinna gives some disturbances to the action of telephone receiver, and consequently reduces its transmission quality. The acoustic impedance of this leakage path is very changeable in accordance with individual difference, the shape and material of earpiece, the method of coupling the earpiece with the pinna, and so on. In this paper, the measuring method of the acoustic impedance of leakage path consisting of acoustic mass L and acoustic resistance R, and acoustic compliance C in closed chamber is made clear. And these values are obtained on several typical earpieces of telephone receivers. Also analysis on acoustical characterestics is made to some entent by observing the avarage curve of actually measured leakage characteristics and supposing the electrical equivalent circuits including the ear cannal.