18KHz. Intercom: Sustained, Built-in Microphone. Operating Temperature level: -20 ～ 50 ℃. Measurements: 283.1 * 224.3 * 269mm. Network Ceiling Speaker GEN-6211A03 Power Supply: DC 24V/1A or POE. Communication Protocols: TCP/IP, UDP, SIP, ONVIF. Signal-to-Noise Proportion: > 80dB. Frequency Reaction: 100Hz https://cashbbxsg.newsbloger.com/30544421/the-duty-of-an-ip-paging-microphone-in-effective-work-environment-interaction