Sound proof helmet?

So I wanted to ask you guys a question that I've been mulling over for the past few weeks. Is a soundproof helmet possible? In the Star Wars Republic Commando books by Karen Traviss, the RCs have helmets that allow them to talk to their squad without the outside world hearing them - they can scream as loud as they please without anyone noticing. On the other side, they can switch to a speaker to talk to people outside of the helmet.
What are your thoughts on this? The RC helmets seem to be large, which would allow more things to be installed. My original thought was to use a thick foam and visor to help reduce my own sound, until I realized that I wouldn't be able to hear what other people are saying either. My second idea came to me as I was using a respirator to resin some pepakura. Would it be possible to wear a (half mask) respirator inside a helmet? With both a respirator muffling your voice and a (semi padded) helmet, I would assume it would be difficult for others to understand you when speaking in a normal voice.
That's where the electronics would come in. You could remove the side filters to allow a microphone to be installed (speaker in chest plate) and a two-way radio earpiece on the other side.

This is just me thinking out loud, and I have no idea if this would be plausible. What do you guys think? Is there anything out there like this? (Also, let me know if I posted this in the wrong section.)

Why do you want a sound proof helmet?

I'm sure space suits and deep diving helmets would be soundproof. Even motorcycle helmets are quiet.

Or a full face gas mask.

terryr said:

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Why do you want a sound proof helmet?

Well, why not? I think it'd be cool to have something like that, even if it doesn't really serve an actual purpose. A friend of mine is building a suit of armor with me, so it'd be cool to be able to talk back and forth I suppose.

Star Wars is also full of a lot of fiction, and I have a feeling that "screaming as loud as they please without anyone noticing" is way more fiction than reality. But it's completely possible to build a radio into the helmet, the easiest way would be obviously cannibalizing an existing radio or walkie talkie or something like that. You'd definitely run into interference and/or other people using the same frequency using it at a con though.

Making a sound proof helmet should be possible, you'd just have to bit of research on soundproofing is all and you'd have to figure out a way of sealing the neck area of the helmet as well. Your idea of putting a half mask/respirator as well as padding your helmet would probably be the easiest and best way to go, this should make your helmet almost completely soundproof.

In order to allow you to be able to hear inside the helmet, one way might be to create headphone like pads around the ears and put no soundproofing behind it and maybe a grill on the outside to allow sound in. The only drawback is that, depending on the seal, you might not be able to hear yourself very well.

Just my two cents, wouldn't it be nearly impossible to make this completely soundproof? I mean you need to be able to breathe. I'm assuming that no matter what, the tubes, etc that you will use will have to be open to some extent which would allow your voice to be heard. Please correct me if I'm wrong.

I probably should have been more specific in my post. I know that 100% soundproof will be nearly impossible. I'm not expecting to be able to yell in it, just to the point where a conversation can be held without others hearing it very well. In order to hear what I'm saying, I'd have to be using a speaker/mic.

The practicality of this idea eludes me, but I'll try to help. MY first idea is a Ground Crew/Ground Support type headset used by ground crews who operate in noisy environments near running jet engines and such.

The microphone portion is covered similarly to the "ear cup" portion and reduces outside noise. You might try to find a used one of these and go from there:

Military Ground Support

Even if you did soundproof the helmet, and cut all the noise coming from your mouth, you'll still make noise, especially loud noises like screaming. Your voice resonates throughout your body. Deeper sounds, like the male voice, resonates through the chest and back, and especially through the throat. You would basically have to soundproof your whole upper body to accomplish full soundproofing.