THE EXPERIMENTAL STUDY ON THE EFFECT OF THE CONTRACTION OF THE TYMPANIC MUSCLES UPON THE CONDUCTIVE APPARATUS

After intravenous injection of succinylcholine to induce the contraction of the middle ear muscles of the cat, an investigation on the transmission of sound through the conductive appa- ratus was made and following results were obtained. 1) The contraction of the tympanic muscles affected the transmission of sound, decreasing the amplitude of the cochlear potential at 400 -5000cps. 2) The effect on the conductive apparatus given by the contraction of the stapedius or the tensor muscle alone was smaller than that given by the contraction of both tympanic muscles. 3) From the above mentioned facts, the effect of the stapedius and the tensor muscle upon the conductive apparatus was assumed to be cooperative.