Testing Room Acoustics and Analysis Tutorial for Home Recording Studio

One of the essentials in building a home recording studio is to test the room acoustics and analyze it for possible issues. This is a tutorial on how to do this procedure. Before moving forward below are the requirements before you will start analyzing your room acoustics:

a.) Set up the studio monitors, DAW, etc. as completely as possible.
b.) Try turning on your PC and studio monitors’ then play some music, you should be able to play music for both monitors.
c.) If you have subwoofers, you might as well add them so that you can analyze the room acoustics with the subwoofer.
d.) Try putting your room acoustic treatment materials as completely as possible. This includes putting bass traps, absorption materials, diffusers, etc.
e.) Make sure you correctly arranged the studio monitors; it should form an equilateral triangle with the mixing position (to where you will sit to listen to the mix). Read more details about this in home studio room acoustic setup.

f.) Download this test tone and unzip it. It is a 24-bit/48KHz mono test tone that will play from 20Hz to 20,000Hz. If your subwoofer or nearfield monitor is only capable of reproducing starting at 50Hz, then in the result, start analyzing at this frequency.

Setup the Test Equipments and Test Tone

Position the condenser microphone (in this test I am using Rode NT1A) at the mixing position (center of the equilateral triangle where you are listening to the mix). Make sure the microphone is at the same level with the tweeters of the nearfield monitors, see screenshot below:

Connect the microphone to your audio interface and switch the gain to moderately high (around 70% to 80%). But switch the main volume/monitor output of audio interface at moderate volume (starting at 50%). This will let the microphone pickup sensitively while monitoring at realistic audio mixing volume. Insert the 24-bit/48KHz test tone in your digital audio workstation software. Then insert one track ready or aimed for recording, this is where the room response will actually be recorded. See screenshot below for this configuration in Reaper:

Running the Test Tones to measure room acoustic response

It is recommended that you will record the test tone at the same bit depth and sampling rate as the reference test tone which is 24-bit/48KHz. Finally you can hit the record button and while test tone will be played; the condenser microphone will then capture the room response by recording the monitored test tones. Be careful of very loud volume, it can damage your ear. I recommend you will go outside of your control room during this test. Also I recommend doing the test 3 times, first at 50% monitored volume, then the second at 40% volume and the last at the softer volume of 35%. The objective is to check the room response at different volumes and decide on the best monitoring volume for mixing accuracy. For example below is the Reaper output after recording the test tones to measure room response at 3 different volumes:

Analyzing the Test Results

First, normalize all the waves to -0.2dB (which is similar at the test tone maximum peak volume). Then run the result through frequency analysis software. I am using Adobe Audition 1.5 for analyzing the frequency response of the recorded test tones. If the recording software does not have this feature, you can use this open source solution.

Download Right Mark Audio Analyzer then install it to your computer. Launch the program then click the spectrum analyzer icon (see screenshot):

Then it will open the wav file for analysis automatically plots the results; select a high FFT size such as 65536. Finally below are the room acoustic analysis results of the above test:

The ideal or perfect result is the bottom graph (labeled as “ideal result). Monitoring at lower volume during mixing (around 30% of the maximum volume) results in a flatter/smoother overall frequency response. Monitoring at louder volumes can slowly inflate the bass even with bass traps because there are leaking reflections of the bass at louder monitoring volume. For some setups, 30% of the maximum volume is very quite; so slowly increase the monitor volume until all the musical instruments can now be heard. The acoustic treatment of the room above is very basic although the result above says that much can still be improved with the current acoustical treatment. If you find out that the room responses is severely skewed or out of balance, then add more acoustic treatments and do it correctly.

Content last updated on July 21, 2012