It states it is for Industrial noise detection module, decibels, 485 ttl uart noise sensor, sound level meter, noise level meter, noise, sound module. I believe you can spend weeks with the A/D and get nothing but noise. Without a complete specification I cannot give you a known valid answer but to me it appears to be a A sync serial signal. That indicates you need to receive with UART or software serial on the Arduino. The TTL indicates that the signal is a TTL level signal, not an analog signal. This is a digital signal that can co directly to the arduino input. No idea if you need a pull up but you probably do. If you have a scope or logic analyzer finding the baud will be easy.
The unit comes already calibrated. To calibrate it you need a fair amount of expensive equipment. They say it is: RT-ZS-BZ- * On-board noise module, in accordance with the national standard GB / T 3785.1-2010 "Electric acoustic sound level meter Part 1 : Rules and International Standard IEC 61672-1: 02 up to level 2 X sound meter design requirements, mainly used in noise conditions In workplaces where noise, traffic noise, noise, building noise and house noise, such as measuring all kinds of noise in real time.There is this module, the client does not need to disturb the noise of complex signal processing, can focus on the field, the customer more quickly Create the measuring setup. his response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!