Masking

No this is not a post about safety in the studio during the current pandemic debacle, but, I’m going to talk about masking in a recording situation.

Basically, masking is when a sound that is on a recording is covered up or masked by something else.

This all has to do with signal to noise ratios.

In the older days a majority of recordings were done in recording studios. Now the actual definition of a recording studio is left a bit to be desired but usually it was considered a space that was designed or utilized for recording sound.

It was supposed to be quiet, and allow for separation of different sounds if one wanted that. The picture of the large recording console with the big window and you can see the artist in the recording room from the control room is forever etched in my memory.

They went to great lengths in commercial studios to cut down on noise. And there was quite a bit of science involved, as some of the best studios in the world are located in some of the most densely populated cities.

Some of the structural engineering was just amazing. They would ‘float’ floors on rubber pucks so that the vibrations from car and d truck traffic, trains and even airplanes would not be transferred to the floor. The inner walls were ‘detached’ so there was no contact with the outer wall thus cutting down on noise and vibration transmission.

Heating and air supplies were run through a series of ‘muffler’ type contraptions so there was basically no noise from any of the HVAC system.

Special doors with gaskets and locks were developed so the sound couldn’t escape through a door.

Those big windows you see pictures of were usually two thick pieces of glass and they were installed at angles from each other further squelching the tendency of sound waves to make it through both plates.

The acoustic properties of these top notch studios were rocket science in the way they dealt with all that sound created inside of the studio.

No sound in, no sound out. All that audio energy had to be dealt with.

Traps, diffusers, deadeners were utilized to turn sound waves into mechanical energy and effectively absorbed. Fiber glass, certain types of foam and uneven surfaces where utilized to tame sound waves.

And it all had to be done so the sound in the control room remained neutral.

In those studios you could put a mic up, crank it to ten and hear… Silence.

But many studios through the years did not have quite as stringent rules. They were none the less actual working recording studios.

Through the years, my dedicated studios were far less refined than the commercial studio’s I studied. I used diffusers and deadeners to take care of mid and upper frequencies, but I usually just let the bass roll on through to the outside, and would use lower monitoring levels to combat less than perfect acoustics. I did as much acoustic renovation as my budget would allow.

So, what does all of this have to do with ‘masking’ you might ask.

If you can’t eliminate noise, you have to deal with it somehow.

Cardioid and hypercardiod microphones, close miking technique’s, selective recording times and controlling HVAC in creative ways are all workarounds to noise.

If you have a quiet guitar or acoustic piano part, you have to have the atmospheric noise down to a minimum. If you are recording in your living room and you live on a busy street, you may have to wait until late at night, turn off all the heat and AC and try to get a good take between the occasional car going by.

As you add other elements to your musical masterpiece, masking starts to come into play and you can get away with more noise.

Noise gates are kind of the opposite of masking in that they actually cut the sound off at a pre determined level. If a guitar rig has a bunch of hum, a noise gate can be set to only open when a certain level is present, or in other words, when the guitar is actually playing. The guitar sound is louder than the hum so you don’t hear the hum while the guitar is playing, only when it stops.

If you are too aggressive with the gate, it will sound as if the ending notes the guitarist is playing are being cut off.

Now if there is a lot of other music going on during the guitar part you may not hear that the last note of the guitar is being cut off because that is being ‘masked’ by other instruments or voices.

Same is true with a vocal that is done in a somewhat less than silent space. Background noises can and will be heard is you listen to the vocal track by itself, but when you add other musical sounds, many times the background noises can’t be heard.

They are still there, but are being masked by the other instruments.

Here is a little experiment you can try for yourself.

Plug an electric guitar straight into an amplifier. No pedals or anything to add noise. From the front of the amp, go back ten feet. Now look to your right at a 90 degree angle put a boom box or clock radio on the floor about ten feet from where you are at and set the radio to play a station at a modest level.

Now go back to the center position (ten foot away from the amp in front of you and ten foot away from the radio to the right of you) put a microphone on a stand, send it to a channel in your workstation and solo that channel to a pair of headphones.

Set the mic facing the amp at a foot or so off of the ground. Put the headphones on and set the guitar volume slightly higher than the radio. Use a regular vocal mic like a shure sm58.

Now start to play the guitar. And every so often, move the mic that is facing the guitar amp a foot or so closer. The closer you move, the louder the guitar amp will seem in comparison to the radio. When you get the mic close enough to the amp, you should have a hard time hearing the radio while playing the guitar.

The mic pattern basically only picks up from the front, so the closer you get to the amp the louder the amp is in proportion to the sound of the radio in the room.

This is masking. It is signal to noise ratio. As you get the mic closer to the source, any background sounds get quieter in relationship to the source sound, in this case the guitar amp.

This is also the case for many live recordings that sound so clean, you wonder how did they keep all that crowd noise out of the recording? Masking. Very close miking of very loud sounds.

But, as I said above, the problem starts to compound itself when you are trying to record solo or soft passages. Listen to Bob Seger’s ‘Turn The Page’ and you’ll hear some crowd noise on the quiet first parts but the noise seems to go away as the band kicks in. It’s still there.

In fact, when a band does a ‘LIVE’ recording, the recording crew will have a number of microphones aimed at the audience to introduce the live sound into the recording at any time they want.

On my first studio build I converted the upstairs of a six bedroom 100 year old farmhouse into my recording studio. This house had NO heating and air ducts, and the only heat was old cast iron radiators.

So, in my recording room I had to put in a window air conditioner to cool things down a bit. On warm days, I had to get it as cool as I could before I started tracking in that room. I would turn the AC off while tracking and turn it on in between takes. If it was real hot outside we would take small breaks from time to time.

I got good at gauging when to take these breaks as the singer was working, trying not to upset when he or she was going strong.

Many times, I actually went to a clients house to record the artist and I would usually set my portable studio up in a spare bedroom and use another bedroom or the living room to track vocals and instruments.

In those cases sometimes the noise level was a bit more than I would have liked so because I was usually the main instrumentalist for the project, if there was I spot I could faintly hear some noise I would add a sound / instrument to cover up the noise. Worked every time. Masking.

Also, from time to time there would be a vocal that for whatever reason, I could not fix. I might have just inadvertently missed it when I was at the artists residence and because of their repetitiveness, none of the takes I recorded sounded right. And I couldn’t fix it with the DAW.

When listening to music in a general fashion, when a new instrument is introduced, the listeners attention will always be momentarily focused on the new sound.

So I would ‘mask’ a problem by introducing a new sound at that given moment. That is also a form of masking.

It’s funny that when I get done with a mix and the artist hears the mix, sometimes they’ll ask why I brought an oboe into the mix on the third verse (or something like that).

If they didn’t suffer from OCD, I would tell them why.

If they had problems with the Idea that somehow the vocal wasn’t exactly perfect, I’d keep it to my self. I learned that the hard way.

Remember these were projects with very limited budgets and many were done on shoestring financing, and the principles were many, many miles away from each other.

Another way of dealing with a noise issue is just renting time at a good studio (if you have the budget) to track the parts that need a good quiet space. Then you can take it home and do all the other stuff you want to do to it with your workstation in your home recording area.

I remember an engineer telling the story of listening to some of Bruce Swedien’s solo tracks of Michael Jackson’s vocal. He said that when the vocal was soloed he was amazed at how much shoe/floor noise there was on the vocal track from Michael dancing while he sang.

So, masking is a very usable tool to the serious recording engineer or artist recording their own material.

Good luck and keep recording!

Author: Chad