Development of Earphone with Variable Frequency Filter
Yoshiharu Koya, Takahiro Kubo · Transactions of the Institute of Systems Control and Information Engineers · 2025
In factories that handle metals, steel, and other materials, the noise produced by machinery and manufacturing processes is called noise owing to its loudness and high frequency. Earplugs are primarily used to prevent noise-induced hearing loss. However, because earplugs block out all external sounds, including work conversations and warning sounds, there is a need for earphones (earplugs) that can selectively allow essential sounds, such as speech and danger alerts, to pass through while blocking other external noises. We propose a method for discriminating whether a signal contains speech using a bilateral clamper. In this study, the noise-only regions did not produce any output, making the earphones function similarly to regular earplugs. The signal containing the voice is subjected to noise reduction by a low pass filter.