18KHz. Operating Temperature level: -10 ～ 50 ℃. Measurements: 440x300x44mm. Zone Combining Digital Amplifier NBS-2301 Power Supply ： AIR CONDITIONING 220V, 50Hz. Power ： 130W ， 260W ， 360W ， 550W ， 700W. Interaction Procedure ： HTTP, TCP/IP, UDP, ARP, ICMP, IGMP. Signal-to-Noise Ratio ：. Mic Input 01: ≥ 65dB,. https://powerline69024.losblogos.com/29459740/the-function-of-an-ip-paging-microphone-in-effective-office-communication