thank for the speed control box option.
sure wish 30 years ago they just put in a quieter fan (say 1 sones) and done with.
Now, unless I tear up the wall and rewire the bathroom light and fan, there isn't much I can do except replace the fan motor, which I did with similar noise.
The NuTone 696N fan housing is small 7" x 8" with 6" depth, 3" duct. Cannot reach up the duct clearing. In fact, I remember this cheap exact same noisy fan was in a Holiday Inn bathroom I stayed years ago.
The time and money I spent so far, has been far exceed twice over the most expensive quiet fan (say 1 sones) in HomeDepot or Lowes.
Will keep hearing the same household complaint till .....