Anechoic Snare: Room Analysis.

As part of one the assignments I did at college, we learned how to assess how suitable a room could be on an acoustic level, which would give us an idea of how we could record and mix in the room examined.

We were given a chart with a total of 6 rooms, divided into small and large and then told to pick one large and one small from the list to be evaluated. In addition to this our lecturer had recorded a snare drum in each of the rooms listed, each of which sounded different due to the layout and size of the room.

Little rooms Big rooms
Studio 1 vocal booth. Studio 1 live room
Project room. Performance space
Studio 1 drum booth. Empty Room next to Lecture Theatre

 

Our task consisted of two parts, the first was to analyse the room, to work out its frequency response, and second was to use that knowledge to apply a reverb effect to an anechoic snare (i.e. a snare recorded with a minimum of room ambience present.)

I chose to use the Studio 1’s Drum booth for my small room, and the Empty room next to the Lecture theatre. (Pictured below.)

Drum Booth Empty Room

In order to recreate the snare recorded in these two rooms, I needed to first gather some information about the size and layout, because if rooms dimensions included one or more symmetrical walls, floor or ceilings, or a figure which divides into a multiple of the wall sides will cause axial modes, and standing waves.

Axial modes are caused by sound waves bouncing off the surfaces in the room, and at certain angles, (axis) select frequencies will resonate causing standing waves. In addition to this, each of these frequencies has integer harmonics that also resonate.

The lowest of these harmonics is called the fundamental frequency, which causes the standing wave because its wavelength exactly fits the distance between the two walls, and as the integer harmonic frequencies do at their multiple (example 2nd Harmonic will become a problem because it will fit exactly twice within the room.)

 

Anechoic Snare.

To apply reverb to my annechoic snare, first I created 3 stereo channels, and imported the annechoic snare, snare two, which was the recording of the snare in the empty room, and then snare 5 which was the recording in the drum room.
Anechoic Snare Tracklisting
I then created two auxiliary channels for the two recreated snares, this involved using the sends on the annechoic snare channel and sending them post fader out on bus 1-2 stereo to the empty room auxiliary. And bus 3-4 to drum room auxiliary.
Anechoic Snare Mixer Window Track Listing
I then added the plug in effects d-verb to act as my reverb to both auxiliaries, As well as a seven band graphic eq to help me adjust the reverb to match that of the rooms frequency response. Finally I added the blue cat plot spectrum to show a visual representation of each tracks, so that way when looped I could view what effect the eq was having to the sound as I changed it.
Anechoic Snare Empty Room EQ Anechoic Snare EQ Drum Room
It was important that the eq came after the reverb, as you want to adjust the reverb to make it sound more like the room, the other way would just be making the snare have the same frequency response as the room, and then adding reverb
Using the fuzz measures frequency response setting, it showed me how much to adjust each frequency by so by looking at the EQ above you can see which frequencies i have boosted which ones i have cut.
 Measurement 2
Frequency Response - Middle
Once I had adjusted the eq so it looked and sounded close to the original, I then had to load up a second feature on fuzz measure, which was the reverberation time, which allowed me to take a average between the highers and lowest EDT ( estimated decay time) being measured in fractions of a seconds, after this was done I adjusted the reverbation time by looking at the highest and lowest decay times and then took an average.
Reverberation Time Measurement 2 - Reverberation Time
Drum Room Empty Room
bellow 100hz isnt that acuurate due to fast furier transmission, which bascily means because there less harmonic content, its really hard to get an accurate reading,
Liam