In this application, FFT analysis of the noise generated from an inverter etc. can be easily performed by using the LA-7500 integrating sound level meter with the LA-0703 spectrum monitor function (option, maximum frequency: 25 kHz.) The results are stored to an SD memory card. Any special software is required to read the stored data, simply by connecting the main unit of the sound level meter to a PC via USB cable or inserting the SD card into the PC card slot. Moreover, installing the LA-0704 sound recording function (option) to the LA-7500 enables recording the original sound data to an SD memory card for a maximum of fifteen minutes. The recorded data can be played back as sound data by the PC with speaker function, or analyzed by the DS-3000 data station with the octave analysis function.