The acoustics of a recording studio are an integral component in producing quality audio content.  It provides the foundation that the rest of the recording process stands on.  When you sit down and speak into a microphone it’s not just picking up your voice coming from your mouth, it’s also picking up all the reflections from your surrounding environment.  This reverberation might be desirable for some instrumental recordings, but not for voice work.

There are several parts to creating an ideal recording space.  I’ll start with arguably the most complex: the room construction itself.  The name of the game for a recording studio is isolation.  You want to reduce as much outside noise as possible, it makes the rest of the process far easier. To do this you essentially build a room inside a room, with the floor, walls, and ceiling decoupled from the outside layers.  There are many ways to accomplish this but it usually comes down to multiple layers of plywood or drywall and soft spacers that connect the inner and outer layers of the room but do not conduct vibrations.  The multiple layers of plywood or drywall help in adding more mass which helps absorb any outside sound that might make it into the studio.

With that part finished it next comes to the materials used on the interior surfaces of the room.  At this point I’d like to introduce the subject of this post.  Studio D. 

This space was an office in the time before this studio overhaul project began.  With the growth of our news department it was decided that we needed to expand our current studio work space.  It appears that when this room was originally constructed it might have been intended to be a studio, but that idea was never fully completed.  Two of its walls are double drywall and isolated from the studio next door and the hallway, but the other two are brick and concrete.  With a 13 ft ceiling and a two large windows the reverberation in this space was extreme.

Interior material choice has the next greatest impact on recording quality.  The structure of the room is the biggest part in giving you the lowest amount of ambient noise.  The interior dictates how sound reaches the microphone from within the room.  NRC is an important part of this stage.  NRC stand for Noise Reduction Coefficient.  That is to say if a surface has an NRC of 1, it absorbs 100% of sound that impacts it.  An NRC of 0 would reflect all sound.  

Brick has an NRC of around 0.02, drywall 0.15, and glass 0.02.  These are all very hard, reflective surfaces bouncing sound around inside this fairly small room. We made some reference recordings with Matt Bush, Helen Chickering, and Cass Herrington all reading the same script in the untreated room.  I suggest listening to these with headphones to hear the full detail of the recordings.

 

You can immediately tell that they are standing in what feels like a relatively small room.  There is a lot of reverb present in the recording, and I can tell you it was far worse when standing in the room recording it in person.

To knock down the reverb and absorb these bouncing sound waves we used acoustic panels.  Acoustic panels come in several varieties like firm fiberglass boards, more flexible batt type insulation sheets, and convoluted/patterned foam.  Each has its strengths and weaknesses but they all share an important property: they are all excellent sound absorbers. Depending on the thickness of the material, acoustic panels and materials typically have an NRC between 0.60 and 1.00.

We opted for a mix of large bass traps ( larger, denser panels with a mix of firm fiberglass and batt type fill that are placed in the corner of a room, where lower frequencies tend to build up and reflect from more) and firm panels spaced out around the room.  The bass traps were from ATS Acoustics, and the firm panels were from Acoustical Solutions AlphaSorb line. 

Four bass traps were installed in the corners of the brick wall, two at about head height, the other two just down from the ceiling.  A total of 7 12″ x 48″ x 2″ panels around the room and 3 12″ x 48″ x 1″ panels to go between the desk and the wall behind it.

After all the panels were mounted we made another set of recordings, using the same script as before.

Can you hear the difference? This is a massive step towards making this a good recording studio.  I think we can still improve the space and eliminate the little bit of reverb left, and that might take some experimenting to find the right placement and material for this situation.  But as it stands, this is now a totally usable studio for our air and news staff.  

Next step is setting up and configuring our new studio hardware and the audio network behind it.  Stay tuned for more info on that.