Improving noise reduction for ear muffs

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    Noise Reduction
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Discussion Overview

The discussion revolves around improving the noise reduction qualities of ear muffs, particularly focusing on the choice of materials for the lining that contacts the ears. Participants explore various approaches to enhance comfort and sound attenuation, considering both acoustic and thermal properties.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that their modified ear muffs amplify internal sounds like heartbeat and respiration, suggesting a stethoscopic effect due to the lining material.
  • Another participant distinguishes between ear "muffs" for warmth and ear "protectors" for sound protection, implying different design purposes.
  • Some participants propose using multiple layers of different materials for the lining to improve comfort and sound attenuation, while others caution against using more layers than the original due to potential issues with usability.
  • A participant raises the idea that pressure on the tragus may affect sound perception, suggesting that the modified muffs might be causing this issue.
  • There is a discussion about the benefits of using two layers with air between them to achieve better sound attenuation compared to a single layer.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of using multiple layers versus sticking to the original materials. The discussion remains unresolved regarding the best approach to material selection for improved noise reduction.

Contextual Notes

Participants have not reached a consensus on the optimal material or layering strategy, and there are unresolved questions about the effects of pressure on sound perception and the specific acoustic properties of the proposed materials.

Glype11
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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?
 
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Glype11 said:
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.
 
Stephen Tashi said:
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.
 
Glype11 said:
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.

Glype11 said:
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.