18KHz. Intercom: Sustained, Built-in Microphone. Operating Temperature: -20 ～ 50 ℃. Dimensions: 283.1 * 224.3 * 269mm. Network Ceiling Speaker GEN-6211A03 Power Supply: DC 24V/1A or POE. Communication Methods: TCP/IP, UDP, SIP, ONVIF. Signal-to-Noise Proportion: > 80dB. Frequency Reaction: 100Hz https://andersonkdqdp.elbloglibre.com/29909975/why-an-ip-paging-system-is-necessary-for-modern-organizations