| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technology of improving the frequency characteristics by an acoustic method so that a sound is heard with natural frequency characteristics when a sealed earphone is attached to a human ear. <P>SOLUTION: In the sound passage which extends from a diaphragm of an electroacoustic converter in a sealed earphone, passes through a cylindrical sound conduction tube and reaches the tympanic membrane via the external canal, two independent passages of sound wave are provided in the sound conduction tube. Transmission of sound having a specific frequency is limited by adjusting the difference of the lengths of the passages, thus improving the frequency characteristics of a sound passing through the sound passage. <P>COPYRIGHT: (C)2012,JPO&INPIT |
