Does the iphone 5 lifeproof case cause it to sound muffled when talking?

Does the iphone 5 lifeproof case cause it to sound muffled when talking?

YES! I have had it now for about a week. Not only can you not hear very well through it, but you also get TONS of squealing feedback through the earpiece when holding it to your face. Here is the reason. What happens when you place a speaker next to a microphone? Feedback! The iPhone 5 has a small microphone on the back near the camera to silence background noise during conversation and also has a microphone you speak through. Well it has an earpiece as well that emits sound. Keeping all that in mind, the case acts as a speaker itself per Life Proof's website. When you combine all those receivers and speakers in 1 confined case it distorts and causes serious feedback.
Another issue is, because the earpiece is doesn't rest flat against the glass, the dimming sensors that detect when you place the phone against your face and when you hold the phone are shadowed causing the phone not to illuminate when bring the device down from your face to end a call.
Also, when placing someone on speaker phone they can hear themselves talking because the voice is trapped inside the case and traveling to the microphone.
The last issue is sound quality. When playing music from the device the sound quality is terrible. It sounds like squeezing a solo cup. It's so distorted and rattles so much you can't even determine what song is playing.

Here is the plus side. This is by far the BEST phone protection you can buy! The case is solid, waterproof, moisture resistant, dust proof, and looks and feels great all while being very lightweight and NOT bulky.

I'm returning mine right now.