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Furry sound blanket…


Bill Kerrigan

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I’m a documentary DP… and carry a number of 6’x 8’ pieces of various black material in my van.

One of my black blankets is made of faux fur, which is also used to keep people warm in the winter.

 

On a number of occasions, when hanging a sound blanket to dampen a live room, I’ve doubled up the blanket, by adding the synthetic fur... with the pile facing the mic.

 

I’m aware of the differences between furniture blankets, professional sound blankets, sound reflection and noise absorption.  Scientifically I don’t know if using the faux fur helps… it just seems to make sense.

 

I’d like to get an expert opinion.

 

Thanks…

 

Bill

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I guess I'm looking for the opinion from an experienced sound engineer... my findings would be purely anecdotal.

 

It's my understanding that synthetic fur is used to cover microphone blimps... because of the furs ability to disperse the unwanted acoustic energy of wind noise. 

 

I was hoping someone with technical expertise, could tell me if the properties of synthetic fur might be better in preventing sound reflection and absorption than a common sound blanket.

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Sound blankets are commonly used for this purpose, no one I know uses a faux fur material for sound deadening. This goes for location recording as well as permanent installation. I am sure it would do in a pinch, but over time the dirt and dust certain to accumulate would make it a messier option.

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Hi Bill,

The reason why sound blankets and furniture pads (and I personally don't think that there is a difference between the two, except maybe from a marketing perspective) work well, is because sound waves bounce from hard surfaces much easier (and louder) than from soft surfaces. The sound blankets will do some absorption, essentially reducing the level of echo or reverb in the room (to a degree).

I wouldn't say that how furry the blanket is would have an effect on how much you can dampen the room. The thickness of the blanket will definitely help increase absorption though.

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Faux fur used to reduce wind noise makes sense.

 

Faux fur used to reduce reverberation in a room makes less sense. Most often we, sound pros, use thick stuff with some mass. Its really to do with sucking up those sound reflections and deadening them. Thick drapes work well, and in fact lead curtains have been used before. It is usually a mass thing. If your faux fur is lightweight, then it is probably making little or no difference.

 

That said - the fact that you care about us, in fact that you even give a thought to us, about us, makes you a total superstar in my world.

 

King Bill, DoP - you are my new superstar !!!!

 

Kindest,

 

Simon B

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As Simon points out, broadband frequency absorbtion requires mass and volume both. The furniture blankets we use are relatively quite dense. They do very little at low frequencies, but do quite well at mid to high frequencies. My guess is your fur only attenuates high frequencies. That may be helpful in certain situations, but in general what you really want is broadband absorption.

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FWIW:  Natural fibers are much better for sound absorption than synthetic ones.  Natural fibers are typically more porous.  Look at a nylon carpet under a microscope and what you'll see is basically thousands of tiny strands of mono-filament (like mini fishing line) material.

 

Also, hanging a furnie away from a wall will extend its lower frequency absorption a bit as it becomes more of a broadband absorber.

 

 

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Well, it depends on the type of fur, but the fact that dead cats exist should give you a clue as to what the likely physics are. If furry surfaces dampened sound, they would not ever be used for dead cats, since the function of a dead cat is to let sound waves penetrate - this tells you immediately that it's unsuitable for sound deadening. What the hair does is to stop the kinetic energy of wind as the hair absorbs the wind's energy to prevent rumbling and/or whistling against the mic grid and surfaces, so that aspect is desirable in a dead cat. In contrast, the sound wave energy is not absorbed appreciably by the fur - except some upper register - allowing you to record through the mic. 

 

You want blankets that are denser and/or reflective. The denser blanket will absorb the sound waves, and reflective surfaces will deflect the higher frequencies. Fur is not desirable here; of course, if the fur is sitting in a strata that is dense, then the dense strata will absorb sound, but that won't have anything to do with the furry hair. Fur hair by itself is not dense - that's why it's fur, with spaces between the individual hair strands, it's the opposite of dense, and so doesn't stop lower frequencies, and fur - unlike reflective surfaces, which it is the opposite of - doesn't deflect, and so doesn't stop most higher frequencies (with the caveat that the upper register of higher frequencies are stopped by almost any obstacle, even fur), which makes fur ideal for sound-noninterference in a dead cat. 

 

Bottom line: fur does nothing for you, any blanket that either absorbs (dense) or deflects is what you want, and fur does neither.

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Well, it depends on the type of fur, but the fact that dead cats exist should give you a clue as to what the likely physics are. If furry surfaces dampened sound, they would not ever be used for dead cats, since the function of a dead cat is to let sound waves penetrate - this tells you immediately that it's unsuitable for sound deadening. What the hair does is to stop the kinetic energy of wind as the hair absorbs the wind's energy to prevent rumbling and/or whistling against the mic grid and surfaces, so that aspect is desirable in a dead cat. In contrast, the sound wave energy is not absorbed appreciably by the fur - except some upper register - allowing you to record through the mic. 

 

Thank you... this makes sense.

I'll leave the fur in the van.

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BK: " I guess I'm looking for the opinion from an experienced sound engineer... my findings would be purely anecdotal. "

my opinion is: it depends

and my opinion, or other folks' opinions are njust that: their opinions.  your personal results are all that counts...

" My quest is to know if it's better. "

you have been testing (questing) for 7 years... what do you think; and if it works for you, then all is well...

" I've been use both the synthetic fur and a sound blanket cliped together, in the hope it might make a difference. "

well...?  has it ??

 

" I'll leave the fur in the van. "

make a coat

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