"Impulse Response"

[zorrow]

Hi there guys! Can anyone explain to me what "Impulse Response" is? I googled around and did find several articles, but none short and clear enough for me to get a quick idea about its benefits. Also downloaded the SIR2 VST plugin. A friend of mine told me it was "the shit" to produce "killer mixes". Would anyone mind vulgarizing a bit about the subject here, please?

TIA!

[zenmindbeginner]

It's a way to capture the acoustic properties of a room or environment and is the basis for all of the fancy CPU hogging convolution reverbs out there.

Essentially a way to liven up a flat recording, it's strength is in mixing... I doubt that processing whole mixes through convolution reverbs will have any real beneficial effect unless like I said, the recording has no depth and is flat as a Thai tranny's chest.

It's used in noise canceling technology like headphones and hearing aids.

Cosmologists use it a lot... modeling technology depends upon it.

If you were to be shot with a pistol, the tearing of the bullet through your body and the subsequent tissue and or organ damage would be your body's impulse response to the "pulse" or "shock" that is the bullet.

The creation of a digital filter depends highly upon measuring impulse responses

That's my layman's definition... maybe there are some actual scientists or mathematicians here that could elaborate further and or correct me.

[geoff_hartwell]

You had me at

... flat as a Thai tranny's chest.

that is all

[burningyen]

An impulse is a sudden, super-quick signal. An audio impulse would basically be a "pop." An impulse response is an audio file of the response of a physical object to an impulse (for example, a recording of a clap or a gunshot in a church). You take that audio file and mathematically combine it with whatever other audio file you want, say a guitar track, and you magically end up with the sound of the guitar playing in the church.

[JGale]

Or, more topically, the reason behind Feynman's guitar acquisition of the yarins.

[Feynman]

I've heard that if you want to produce killer mixes, those things are the shit.

[crunchee]

Cosmologists use it a lot... modeling technology depends upon it.

Where do you go to, to learn how to use it? Beauty School?

Oh. I thought that was Cosmetologists. Wrong kind of modeling, too. I kid, I kid!

Will it fix or enhance a flat sounding amp (and by extension, a flat sounding guitar) in the mix?

[zenmindbeginner]

Cosmologists use it a lot... modeling technology depends upon it.

Where do you go to, to learn how to use it? Beauty School?

Oh. I thought that was Cosmetologists. Wrong kind of modeling, too. I kid, I kid!

Will it fix or enhance a flat sounding amp (and by extension, a flat sounding guitar) in the mix?

They used to try and replicate rooms by the decay time, early reflections, pre-delay, diffusion and timbre. Now, they don't have to and actually go around and sample various spaces and get accurate acoustic representations.

Now you can actually be in a cathedral instead of saying hmmm... cathedrals are huge and require long decay times and massive pre-delays, give it some diffusion without much filtering and start building up the early reflections until everything bounces around sort of like in a cathedral. Nowdays, some arsehole has gone around and sampled several old churches and the old ways of building specific acoustic environments through coarse instrumentation are long gone.

[zorrow]

Thanks for the replies, guys. I think I finally got it, as I had some spare time to read a couple of articles and try SIR2. It's actually a very sophisticated reverb. Dry takes come "alive" when the right environment is chosen. It can also enhance the sound of your take in many different ways, depending on the impulse you're using -for example, you can get more attack, or get a "denser" sound, or a "crispier" tone and so on... It's definitively good stuff!

[Hackubus]

SIR2 is a nice reverb plug, but it'll take more than verb to make 'killer mixes'.

Another cool thing about SIR2 is, you can use cabinet impulses with it instead of reverb impulses and place the plug after a guitar sim say Amplitube2 for example, turn off the cabinet emulation in the guitar sim & use SIR2.

In my earlier days of Protooling before I had Amplitube2 or Eleven rack, I'd record a guitar track with the old 1st gen POD with the air switch turned off, put the SIR2 plug with cab impulses on the POD track to get it sounding amplike again. Sounded verrry nice.

Now that I think about it, I've used SIR2 more as a cabinet impulse emu than I ever did as a reverb plug.