When choosing and installing an air conditioner, it is worth paying attention to the noise level, if you are planning to install in the bedroom or next to the window of nervous neighbors, you should definitely take into account the noise level that the outdoor unit emits. It is measured in decibels (dB), sounds with a level of up to 25dB are practically inaudible, the whisper level is on the order of 25 to 30dB, the volume of a normal conversation and office space is 35-45dB, all that is higher is a loud conversation or a busy street. For modern the characteristic noise level of the outdoor unit in the range of 40-45dB, for the indoor unit - 25-35dB. You can notice that the volume of the indoor unit does not exceed the volume of the office space, so you should pay attention to this indicator if performed, for example, in the bedroom or personal office.
It would seem that the choice is obvious, the lower the noise level, the better and comfort will be guaranteed. But this is not entirely true and it may turn out that an air conditioner with a noise level of 25dB will work louder than another with an indicator of 32dB. And there is no deception here, as modern climate technology can work in various modes, and each has its own level. You need to be prepared that other systems can also make split systems - gurgling, hissing, crackling, clicking. Freon's gurgling and hissing can be heard when the compressor is turned on or off. Cracking can occur during compression or expansion of parts of the body when the temperature changes. You can recognize the indoor unit that makes crackles by cheap plastic, which is easy to distinguish from the expensive plastic of any other high-end model. Clicking may occur when the compressor is turned on or off.
It is known that the air conditioner needs to be operated only when the windows are closed, so the volume of the outdoor unit is almost inaudible, but it can be heard by neighbors who do not have air conditioning and all windows are open. Of course, the volume indicator of a working outdoor unit does not exceed the level allowed for the living area, but it can annoy the neighbors, so you need to think carefully about the installation location.