Improving noise reduction for ear muffs

[Glype11]

The lining on my ear muffs which contact the ears, developed cracks and eventually split apart. I decided to try and repair the muffs, so they would have noise reducing qualties than those were better than any typical store bought muffs.
Unfortunately, the finished product, reduced the outside noise, while amplifying the sound of my heartbeat and respiration. The net result was a louder sound with the muffs on than off. Moreover, the material I choose for the lining was hot and uncomfortable on the ears.
I realize the issue is with lining which acts like a stethoscope. What would be a good choice of material to use for the lining?

 

[Stephen Tashi]

The lining on my ear muffs which contact the ears, developed cracks and eventually split apart.

I think of the purpose of ear "muffs" as providing warmth. Ear "protectors" or ear "defenders" provide sound protection.

What would be a good choice of material to use for the lining?

Perhaps you shouldn't restrict your thinking to one material. What about several layers of different materials? You could use the original materials in the layer next to your ear if those materials were comforable and non-stethoscopic.

 

[Glype11]

I think of the purpose of ear "muffs" as providing warmth. Ear "protectors" or ear "defenders" provide sound protection.

No, there are acoustic and thermal muffs.

Perhaps you shouldn't restrict your thinking to one material. What about several layers of different materials? You could use the original materials in the layer next to your ear if those materials were comforable and non-stethoscopic.

There's no sense in using more layers than the original. The orginal linings have split apart and not usable.

 

[Baluncore]

Unfortunately, the finished product, reduced the outside noise, while amplifying the sound of my heartbeat and respiration.

That is very hard to judge. You normally don't notice the sound of blood flowing near your ears because of the external background noise.

When you block your ears you should hear a rumbling noise centred on about 15 Hz. Maybe your ears are being closed by pressure on the tragus in front of your ear canal, from the lining in the modified muffs. Press the tragus with a finger hear the sound of blood flow.

There's no sense in using more layers than the original.

Well actually there is. Each change in acoustic impedance will reflect energy. By using two layers with air between them, you get more attenuation than one normal layer.