The internet is replete with postings regarding application of damping material to speaker enclosures and mounting areas to improve mid-range and bass.

However, NVH reduction material should be applied closest to offending source....here the speaker frame.

Most speakers use a "spider" type frame...so will start there.

Have plenty of 4mm Boom Mat (butyl with aluminum facing) which to work.

Applied Boom Mat strips to the plastic spider frame and, properly trimmed, fits well.

Considered application directly to magnet, but then thought better of it..

With a contemporary pop CD, adjusted volume to the point I could not feel vibration on plastic speaker enclosure, yet could feel slight speaker vibration on opposing side.

So a difference

Possibly a more fully engineered solution exists, however this is mine

Following are before and after images depicting application of damping material.


OEM plastic speaker spider frame...

After application of Boom Mat material to speaker frame.

 

Added Boom Mat to the back of front speaker (magnet).

This further dampens the speaker.

Noticeable sound improvement

OEM and aftermarket speakers would respond well to speaker frame (spider cage) and magnet damping.

NVH is best controlled at its source...so slathering the entire door panel could be reduced if the source is addressed.


Elected to dampen speaker magnet. Did not cover vent hole.


Damping OEM plastic speaker cage with 4 mm Boom Mat


Boom Mat wedges applied to speaker frame.