... sound and noise of short duration can form spectrum analyzer with external filterfrequency range : 10HZ-20KHZbasic configuration: main machine, microphone, fan ... LED Power DC 6v, 4 pieces of 1.5v batteries, with external DC voltage input holeWith AC accessories, it can be ... used to test with external 220v. Sound calibratorTL 6020 (94dB,1000Hz), TL6020A (94dB/ ...