Tips & Techniques:Acoustics - Hearing your room

Think your room is that great sounding huh? Well try this:

I've attached a test tone file in 24bit AIFF and WAV format that takes a sine wave and sweeps it from 20Hz through to 400Hz over 45 seconds. It's at -6dbFS so be careful it's quite loud! The AIFF format is great because if you use QuickTime player you will get labels for each frequency band visible on the player (and selectable from a menu). These files were made with Make A Test Tone from Audio Ease which I highly recommend for very high-quality test tone generation!

Play this file over your system and have a listen from the mix position. This can tell you tons of stuff about your ability to hear what you're doing, and how it may be compromised.

First off, when playing 20Hz you probably won't be able to hear it. But if you can hear a tone (one above 20Hz), it may be harmonic distortion somewhere in your monitoring chain. That's a bad thing and you probably want to address it by pulling crap that doesn't belong in it out or gain staging things better.

As the sweep goes up, take a look at where you can begin to hear things (or maybe just "feel" them). That's as low as your monitoring will go. If it's above 40Hz or so, you will probably benefit greatly from adding a subwoofer.

Now as the tone goes up, do you hear anything rattling in your room? If you do, that's extra percussion being added to all of your mixes...perhaps it's simulating someone playing tambourine in sync with the kick drum. Obviously, you will undermix "click" for that kick if you have rattles going on. Hunt for those rattles (a steady sine wave tuned to the resonant frequency will help) and tamp them down!

As you ascend in frequency, if the sound gets louder or softer, or starts moving left to right or dipping oddly or something, you are in need of improving your monitoring and/or room. You should first start by taking any EQ off your monitoring...obviously it wasn't working. If you do add EQ, it should be done last, and only as a last resort. Make sure your speakers are wired in proper phase. Then focus on your position in the room (38% of the length of a rectangular room, with 62% of it behind you, is considered ideal by some) and the position of the monitors (their position relative to the walls and corners is important, plus their stereo image and mid-side balance). And then you will probably need bass trapping of some sort to even out the imbalances that remain due to room modes.

Lastly, while sitting in silence at the mix position, clap your hands in front of you to generate a nice little impulse. Do you hear a nice dead clap or is there a flutter echo or metallic resonance? If the sound isn't fairly dead or at least nice in its decay you will need treatments of your reflection points (if the walls were mirrors, where you could see yourself and your speakers) with absorption and/or diffusion measures.

The acoustics forum here on gearslutz is a great place to ask further questions. Remember, you are only going to generate work of the quality that you can hear the flaws of...any flaws you can't hear may well be heard by others when it's too late for you to do anything about them.

But also keep in mind that it costs hundreds of thousands of dollars to design, build and treat a room that won't have problems revealed by this test, so don't worry yourself stiff if you can't fix everything. You will need to learn your room and your monitors even if their frequency response is relatively even. You just want to make sure there aren't gaping holes in the frequency response that will leave your mixes with massive kicks or missing bass notes etc.

Have fun making music peoples! " class="inlineimg" />
Attached Files
File Type: aif 20-400Hz-45sec.aif (5.68 MB, 3498 views)
File Type: wav 20-400Hz-45sec.wav (5.68 MB, 3804 views)
Contributors: mw, peeder
Created by peeder, 28th March 2008 at 10:01 AM
Last edited by mw, 27th March 2012 at 03:05 PM
Last comment by JAMES L KOVACS on 29th November 2008 at 01:02 AM
5 Comments, 27,890 Views



(5) Comments for: Acoustics - Hearing your room Page Tools Search this Page
#1
2nd April 2008
Old 2nd April 2008
  #1
Gear addict
 
emreyazgin's Avatar
 

Thanks for the resource first of all! however,

I think -6dB is too loud for such low frequency, and 24 bit and 44.1 khz is a bit unnecessary for such low frequency material. Just my opinions of course
peeder
Thread Starter
#2
2nd April 2008
Old 2nd April 2008
  #2
Lives for gear
 
peeder's Avatar
 

Thread Starter
Cheers. I wanted the file to be fairly "definitive" as far as quality goes...no one can criticize it in terms of quality. And you are welcome to attenuate it as you wish. Far easier to attenuate than gain in quicktime player and in analog.

In the 90's I bought Mix Magazine's "Mix Reference Disc" and the test tones were simply AWFUL. Aliasing like mad. How could they have printed those? Most test tone files on the web I found people apologizing for them not being the highest quality test tones. So this is my response to all that nonsense.
#3
2nd April 2008
Old 2nd April 2008
  #3
Gear addict
 
emreyazgin's Avatar
 

Quote:
Originally Posted by peeder View Post
Cheers. I wanted the file to be fairly "definitive" as far as quality goes...no one can criticize it in terms of quality. And you are welcome to attenuate it as you wish. Far easier to attenuate than gain in quicktime player and in analog.

In the 90's I bought Mix Magazine's "Mix Reference Disc" and the test tones were simply AWFUL. Aliasing like mad. How could they have printed those? Most test tone files on the web I found people apologizing for them not being the highest quality test tones. So this is my response to all that nonsense.
Yes you are right better quality is always welcomed (of course sometimes it shouldn't exceed the storage, practicality etc limits...but this is not an issue here ) Really good job you have done, Im sure it will be beneficial to everybody..Cheers
peeder
Thread Starter
#4
13th April 2008
Old 13th April 2008
  #4
Lives for gear
 
peeder's Avatar
 

Thread Starter
I found this link from Bob Katz which may be helpful. Although it refers to sounds that I don't see downloadable.

Digital Domain - Subwoofers
#5
29th November 2008
Old 29th November 2008
  #5
Gear interested
 
JAMES L KOVACS's Avatar
 

hey, that is great, except you are forgetting the RT60 reverb.
Witha a swept wave, you get blown away by the STANDING WAVES as it sweeps. But next, try a TONE GENERATOR in a pulsed mode at those critical frequencies (just hitting the MUTE switch on the mixer input is cool).
You will be surprised ! Some of these tones actually degrade into different frequencies (especially in large spaces like Gyms or Stadiums). EEEK !

NEXT get some RT60 analysis software and find out THE TRUTH,,,HAHAHAHA


AND THEN, go for the solutions !
Usually these are acoustical hardware units, Helmholtz tuned resonators and such, before you hit the speaker EQ.

It becomes fun once the pain is over............... Bless ya !
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