Decibel ratings on pumps probably aren't something to be compared unless there is an industry standard of measurement. And unfortunately there usually is not. When measuring decibel readings at such a low level, distance of less than half an inch could make a noticeable difference in readings. Here is a little info to help you understand decibel readings
0dB the faintest sound we can hear
10dB Rustle of leaves 10
20dB Whisper
30dB a quiet library or in a quiet location in the country
40dB Average residence
45dB typical office space. Ambience in the city at night
50dB Average office
60dB Martin Place at lunch time
70dB the sound of a car passing on the street
80dB loud music played at home
90dB the sound of a truck passing on the street
100dB the sound of a rock band
115dB limit of sound permitted in industry
120dB fighter jet at takeoff (deafening)
The decibel scale, like the pH scale that measures acidity and alkalinity, and the Richter scale, which measures earthquake energy, are logarithmic, that is proportional. The decibel scale increases ten fold for every 10 decibels measured. It's base 10, that nemesis from junior high school mathematics. This scale lets us deal more easily with big numbers. The table below shows the problem and how a logarithmic scale solves it.
A fighter jet at takeoff may produce 120 decibels. Does that mean it is 120 times more powerful than our fallen leaf? No. The difference is an unbelievable trillion times. The range of human hearing, between the softest sound you can hear, and the strongest sound you can stand, is well over a hundred million times. To measure that extraordinarily wide range we need an equally wide scale: the decibel scale.
