IR reverbs from anechoic chambers

[Mayae]

Hello,

I'm currently reading through the IR topic but I was wondering if someone specifically knows a collection of mono IRs from "objects" - ie. the filtered sound of an object instead of the sound of a room.

For instance, a wooden door reflects and absorbs sound in a particular way. This can be recorded in an anechoic chamber. Has anyone seen someone offering something like this?

[Gamma-UT]

The result is surely going to be some kind of single, filtered delay? – at least assuming a (near) perfect anechoic chamber. Low frequencies will go straight through with perhaps minimal reflection; high frequencies will reflect straight back for a moderate comb-filtering effect. How much of each is going to depend on the wood and its thickness.

As hardly anybody will have heard this sound, it doesn't seem that it's going to be that useful as an IR particularly as it seems one of the easier things to model with a filter and a very short-period delay.

[Mayae]

The result is surely going to be some kind of single, filtered delay? – at least assuming a (near) perfect anechoic chamber. Low frequencies will go straight through with perhaps minimal reflection; high frequencies will reflect straight back for a moderate comb-filtering effect. How much of each is going to depend on the wood and its thickness.

As hardly anybody will have heard this sound, it doesn't seem that it's going to be that useful as an IR particularly as it seems one of the easier things to model with a filter and a very short-period delay.

Yes it will be! It will be used for modelling surfaces and reflections in arbitrary spatialized geometry. It can therefore be used to simulate any kind of "room" (this includes single objects occluding a point source in free space).

I realize the use case is nonexistant (currently ) and therefore hard to find compared to all the great hall IRs etc. out there, but just in case somebody stumbled upon this, I would be very interested in this.

It can be emulated to some degree through custom built up filters, but a collection of IRs seem to be the most flexible.

[realmarco]

anechoic room don't reflect sound.

so basically Don't use a Reverb on your tracks and thats what it would sound in an anechoic room.

the only way to have an an-echoic room sound is to record audio IN an anechoic room.

you can't replicate an anechoic room

[Robert Randolph]

anechoic room don't reflect sound.

so basically Don't use a Reverb on your tracks and thats what it would sound in an anechoic room.

the only way to have an an-echoic room sound is to record audio IN an anechoic room.

you can't replicate an anechoic room

Perhaps an attempt to read the OP would enhance the quality of your posts.

[jens]

*lol*

typical Realmarco quality post...

[whyterabbyt]

you can't replicate an anechoic room

http://bram.smartelectronix.com/plugins.php?id=5

But you might want to work out what anechoic chambers get built for. The OP's useage is firmly in that territory; he wants pure IRs of the reverberation of real-world objects untainted by the reverberation of the room they're in.

For the OP : Im wondering if IRs taken with a contact microphone would be a sufficiently good substitute.

[dreamvoid]

I would try to use a Dirac Pulse or a sweep 'send' thru the material by a speaker, similar like on a plate reverb, to act as a stimulus and pick it up with a contact microphone. No anechoic chamber necessary. I think you could get the typical resonances of materials. Please report back your findings - this is indeed an interesting topic.

[camsr]

anechoic room don't reflect sound.

so basically Don't use a Reverb on your tracks and thats what it would sound in an anechoic room.

the only way to have an an-echoic room sound is to record audio IN an anechoic room.

you can't replicate an anechoic room

All anechoic rooms reflect sound

[kvaca]

anechoic room don't reflect sound.

so basically Don't use a Reverb on your tracks and thats what it would sound in an anechoic room.

the only way to have an an-echoic room sound is to record audio IN an anechoic room.

you can't replicate an anechoic room

All anechoic rooms reflect sound

exactly
outdoor recording seems like a better option, or - when the noise from traffic is too loud - recording in baloon is another good option

[valhallasound]

My guess is that an IR from, say, an isolated door, would sound fairly different than the IR from that door as part of a room, especially with regards to low frequencies. High frequencies would reflect off of the isolated door in a similar way to the door in a wall, but the low frequencies would largely "wrap around" the isolated door. A door in a wall will reflect most of the low frequencies, if the door is closed.

As far as using a contact microphone on a door: this would be a good way of reproducing the resonances of the door when struck by an object. If you wanted to model different door knocks, or footsteps, contact microphone derived IRs would be great - just convolve the IR with your "impact events." This is much different than the sort of IR you get when a sound is reflected off that same door.

[Mayae]

The contact microphone is a really good idea. As I see it however, whatever gets transmitted into the object is whatever doesn't get reflected. The object will emit this sound as well, which will constitute the occluded sound content for a listener and a point source, with the object inbetween. So this is only one half of the solution.

I'll experiment with the microphone, but I don't think I have access to a dead room for recording reflections. Outdoor is perhaps the better solution, although it really isn't quiet around here.

My guess is that an IR from, say, an isolated door, would sound fairly different than the IR from that door as part of a room, especially with regards to low frequencies. High frequencies would reflect off of the isolated door in a similar way to the door in a wall, but the low frequencies would largely "wrap around" the isolated door. A door in a wall will reflect most of the low frequencies, if the door is closed.

Yes, this is largely the point. This project simulates reverbs and reflections from common materials in a 3D space. Therefore I need the "sound" - or rather the response - of objects, alone.

[Ichad.c]

For instance, a wooden door reflects and absorbs sound in a particular way. This can be recorded in an anechoic chamber. Has anyone seen someone offering something like this?

This should work, but it would probably sound horrible, because being in an anechoic chamber is the closest thing to hell there is IMHO, I was in our state-broadcaster's one, was very close to puking my lungs out, never again!

[Gamma-UT]

This should work, but it would probably sound horrible, because being in an anechoic chamber is the closest thing to hell there is IMHO, I was in our state-broadcaster's one, was very close to puking my lungs out, never again!

It is very weird isn't it? I was surprised at how unsettling it was - it really brings home how much we rely on hearing the reflections of sound.

[bmanic]

We all react differently. Frankly I was very surprised how little our group reacted to it.. and we were in the room for more than 2 hours straight.

I also was part of an experiment with tons of speakers setup in an anechoic chamber where I sat in the middle and they played surround impulse recordings through the speakers, trying to simulate various rooms. It was interesting to say the least... sitting in an anechoic chamber surrounded by 30+ tiny genelecs.