Is a plastic crinkle sound normal with an breast expander, the sound being internal?

If the expander is not completely filled it is not uncommon to hear a "crunching" sound. If you are concerned it is best to address this with your plastic surgeon.

.What you are experiencing is quite common. Breast implants as well as expanders often times can generate perceptible noise due to fluid shifts and occasionally air

so if you're experiencing this, contact your surgeon for reassurances that it isn't anything to be concerned about.  If one expander is smaller than the other and softer, its possible you have a leaking expander.

If the expander is not completely filled you may feel a crunching type sound.  Should not be a problem, Check with your plastic surgeon. 

Thanks for writing, With tissue expanders the idea is to stretch the skin and eventually allow room for the permanent reconstruction: either a flap or an implant, which is usually silicone. As the tissue relaxes and stretches the expander softens and the crinkling can be the bag inside. This typically is not a problem, as a matter of fact this is something we see periodically with normal saline breast implants for augmentation.  I would let your Plastic Surgeon be aware of this. Relative to the hardness around your expanders, again this is something your Plastic Surgeon can answer for you. Good LuckStephen M. Davis, MD, FACSGreen Hills Plastic Surgery 

In one area you ask about a crinkle sound and then you ask about a hard area. I'm afraid I truly do not understand your question. Don't you think it would make sense to contact your surgeon with these questions?