18KHz. Intercom: Sustained, Built-in Microphone. Running Temperature level: -20 ～ 50 ℃. Dimensions: 283.1 * 224.3 * 269mm. Network Ceiling Audio Speaker GEN-6211A03 Power Supply: DC 24V/1A or POE. Interaction Protocols: TCP/IP, UDP, SIP, ONVIF. Signal-to-Noise Proportion: > 80dB. Regularity Response: 100Hz https://franciscobfeca.tkzblog.com/29848627/discover-the-benefits-of-using-an-ip-speaker-for-clearer-announcements