Well, the answer to this question may vary from person to person. Since portable air conditioners incorporate both a fan and a compressor, their sound is quite similar to a window air conditioner. Suppose you pay attention to the product specifications. In that case, you will find the decibel rating for each product stays somewhere between 48 dB (which is the same sound level as rain falling) to 60 dB (similar to noise level as a normal conversation).