Output Noise
We use a high quality CEM-8852 Sound DB Meter at a distance of 50 cm from the NAS for these measurements. The ambient noise in our lab during noise measurements was below 30 dBA.
The fan makes its presence felt while the NAS operates normally, though you can't call it noisy, but it is annoying once its speed increases.
Output Noise Comparison Graphs
The following graphs compare the output noise of N5550 to that of other units we have tested in the past.