CUI Devices IEC 60601-1-8 Medical Speakers are designed to fit the regulations required of devices certified to IEC 60601-1-8 standards. While some speakers can be prone to make popping noises when exposed to abrupt voltage changes, these speakers from CUI Devices offer a maximum resonant frequency of <480Hz. This frequency rating means these speakers meet the minimum requirement of four harmonics of the pulsed frequency between 300Hz and 4KHz.