If you have dual pane windows and laminated glass storms on your home and you are having issues with unwanted sound in your home then I would suggest that there is another issue involved.
The ability of a material to stop unwanted sound from passing thru - including glass - is determined by material mass, material stiffness, and its damping ability.
Increasing the mass of any object will have an effect on sound transmission. Increasing the mass of a window (making the glass thicker) will increase sound attenuation, but not nearly as much as might seem obvious, and since it really isn’t possible to increase the stiffness of glass, that leaves damping the sound as the only remaining variable.
While glass itself has very little damping ability, laminated glass - when putting a layer of a more viscous material between two of lites - substantially increases the units ability to dampen sound. In fact, a single pane of 1/4" laminated glass consisting of two 1/8" glass panes bonded to the plastic interlayer actually has as much sound blocking ability as a 1/2" lite of monolithic glass.
Two things you may want to look at in your situation are -
First, how tight are your windows when closed? That is huge. If the window doesn't sit very tightly in the frame, then you will have sound getting thru the unit.
Second, how "heavy" or tight do the frame/sash assemblies feel to you? Again, they should feel solid - looseness is bad for both energy performance and sound blocking ability.
I would venture a guess that better than 90% of all window problems involve installation, and if you want to stop sound from penetrating the unit, then installation is vital. Are these replacement windows or are these windows in a new construction? If replacement, whose are they and what "type" of replacement window?
All factors considered, a fixed, versus an operating, window is going to to have much better sound attenuation performance, however, having a house-full of windows that can't be opened is not very appealing to most people, so again we come back to the earlier comment that your windows MUST be tight when closed.
Generally, a wider airspace in the IGU is very important when considering sound blocking ability, and having separate storm windows are a definite advantage to blocking sound - especially if they are laminated. But, again if the storm isn't tight then the advantage of the laminated glass and wide airspace is wasted.