If communication waves from cellular or Wi-Fi sources interfere with and intrude into microphone lines for smartphones or other devices, some of their components will become noise components in audible bands known as "TDMA noise", and may be emitted from speakers as unpleasant sound. Countermeasures which implement combinations of TDK's noise suppression filters and ESD Notch Filters can not only demonstrate outstanding effectiveness at suppressing TDMA noise with no effect on signals, but can also provide a variety of other benefits such as improving cellular or Wi-Fi communication reception sensitivity, and providing countermeasures against ESD (electrostatic discharge).