Microphone for dB measurements should be put 1m away from the noise source. Not at 10cm and not at 5m. That's how the noise level gets defined. I've seen noise

Microphone for dB measurements should be put 1m away from the noise source. Not at 10cm and not at 5m. That's how the noise level gets defined. I've seen noise levels on cheap indoor air condition units that have unbelievable good figures; only that they measure at 3m; go figure. Smart phones indicated noise levels are irrelevant since they lack calibration. I don't understand why people discuss their figures.