4 Reasons Why Smaller Auditoriums Should Not Have a Sound Room

I could hear defeat in his voice as he described being the new music director at a small church. Eric (not his real name) wanted to know if I could come down on a Saturday morning and tell them how to fix their sound problems.  I asked a few questions and we set a date.

When I arrived. the pastor invited me in to his office.  He sighed and then began to list the problems that had been having.  He told me of regular complaints from the congregation about volume being too high or low and the sound “not having a good quality”. Also, the platform dwellers were not hearing what they needed in the monitors.  The usual stuff really. I took notes so I would remember to address every problem. But I knew 80% or the problems would be solved with one change.

We finished our meeting and headed over to the church sound room.  You’ve seen them.  Maybe you have one.  It’s a room in the back of the auditorium where all the sound equipment is set up and operated.  And placing the mixer in that room was the cause of probably 80% of their problems.

I will explain, but first I need to introduce one term that will make it easier to communicate. The term is ‘Front of House’.  This is a weird industry standard term like Accounts Payable is in accounting. It is abbreviated FOH and means the position where the sound guy sits who is mixing for the live audience (as opposed to mixing for a radio or internet listener, which would be called a “media mix”).

Why putting FOH in a room was the causing most of the problems:

1. You have to hear the room

This is key:  Mixing for a live audience involves a handful of sound sources

  1. There is acoustic noise in the room.  These are sounds you can hear when the sound system is off.  Some can be significantly loud, like a trumpet section or drum cymbals.
  2. The room itself will resonate when certain notes (frequencies) are sounded.  The room is actually amplifying those frequencies; making them louder.  At the same time, some other frequencies may not be getting through well at all.  As sound waves bounce off of surfaces, some will collide just right and cancel each other out, making them quieter.
  3. There are noises in the room from the audience, air conditioner, traffic outside, etc.  The volume of the FOH mix needs to allows sound sources to be heard above the noise floor.
  4. If there is singing, you should sing a bit to make sure the instruments are not making it impossible for the audience to hear themselves singing.  But you have to be in the auditorium yourself for it to work.
  5. And of course, the sound system joins with these other sound sources as one contributor.

Mixing FOH from inside a sound room is like painting a portrait while wearing a blindfold.

 2.  The FOH person mixing should be as engaged as anyone on the platform

Put another way, the mic should always be turned up on time.  And by “on time”, I mean before the person on the platform starts speaking, singing or playing into it.  There can be a lot happening and the FOH operator needs to be on it.  I’m tough in this, but not having a mic turned up on time is embarrassing for the FOH operator, frustrating for the person trying to be heard and a distraction for everyone in the audience.  Attempting to mix without the ability to hear is bad enough.  But I’ve also found the relative isolation of the room makes it much easier for distracting conversations.  It is important for the FOH mix operator to be as in-tune with every moment of the event as everyone on the platform.  Simply no other person has as much impact on what is heard.

3.  The FOH mix operator should not be concerned about the media mix

This goes along with not being distracted but I wanted to break this down even further.  A media mix is a mix intended for an audience that will listen without being in the room.  Examples would be radio, podcast, live web stream or CD recording.  Media mixing requires a nearly opposite approach than mixing for live audience.  The media mix operator has a goal of providing a sense of the room and live audience feel without having the acoustic and room sounds automatically mixed in.  Acoustic and room sounds must be added via strategic mic placement and mixing.  And a media mix SHOULD be in a room, though it is still important to have a great view of the platform (or video monitors).

Sometimes I am in situations where I have to do both.  My solution is always to mix for the live audience but send direct outputs from the console to a multitrack digital recorder that I take back to the studio for post production in a treated environment.  Get the best of both worlds that way.

4.  The FOH mix operator needs to see the audience and stage well

If people are covering their ears and glaring at the sound operator because it’s too loud, it would be good to be able to see that.  Also, the FOH mix operator must be able to see all of the stage well so cues are not missed.

My advice – If you have a sound room now, keep it!  But...

Placing the FOH mix position in an enclosed room won’t fix every audio problem, but I dare say it will offer one of the greatest improvements possible.  My advice would be, if you have a sound room now, keep it.  Make it the media mix location.  Buy a mic splitter, snake and another mixer that will become your FOH mixer.  Place the FOH mixer out with the audience, ideally about two-thirds of the way back in the auditorium and not under a balcony.

If you have questions, I would be glad to try to help.

Jeff

 

Is there a cheap way to soundproof a room?

The quick answer is: Probably not, but you may already have a room that will accomplish your goal.

This question came to me from a trumpet player that was looking for a way to practice without disturbing others.

There are three principles we will draw on to understand the direction needed:

  1. Sound proofing is achieved via isolation and not absorption.  Most people mistake the zig zaggy foam they see on studio walls as providing isolation.  Foam has another purpose (absorption) and doesn’t really help much at all to keep sounds in or out of a room.
  2. Higher sounds (frequencies) bounce off solid objects like walls and floors and glass.  Lower sounds transmit through typical walls.  Therefore, the steps to achieve sound proofing are determined by the frequency range of the sound source.  Isolating a flute is much easier than isolating a kick drum because with a flute you can go into a typical bedroom and close the door.  An kick drum can transmit through the floor and ground to be heard a block away.
  3. The rigidness, thickness and spacing of the barriers (walls, doors, windows, air space) are factors in sound isolation.  Solid concrete walls will isolate more volume at a lower frequency than sheet rock because concrete is more rigid and vibrates less.  And sheet rock will be more effective than glass.

Let’s look at a few specific examples of how to isolate various sound sources for rehearsing.  I will list them from easiest and cheapest to most difficult.

Flute, clarinet

Since higher sounds will bounce off of walls and the energy of quieter sounds dissipates quickly, a flute player can typically attain practice isolation by simply going into a bedroom and closing the door.  If the bedroom is really close to those you don’t wish to disturb, you may need to go to a bedroom that is farther away.  A flute will not produce sounds low enough to transmit through typically constructed walls and doors.  Note that the slightest crack (like under the door) will allow sound to pass through.

Trumpet, vocals, violin

The volume produced by a trumpet or vocalist makes those sound sources a little more difficult to isolate.  But the relatively high frequency range still works in our favor.  The key is to dissipate the sound before it escapes to the ears of people nearby.  One tool we use in the studio to accomplish dissipation of loud sound sources is a room within a room.  The air between the rooms does a marvelous job of absorbing and further attenuating the sound.  It isn’t practical for most trumpet players or vocalists to build additional structure, but you may already have a bathroom or walk-in closet that offers the option to put two doors & walls between you and the family.  If that doesn’t work, practicing in the car will demonstrate how well this works.

Trombone, Tuba, Electric bass

Instruments that produce low sounds require a room within a room and also physical isolation from the floor.  A platform on foam can help.  In my studio, the floor joists were constructed on U-shaped thick rubber that prevents low notes from transmitting through the “floated” floor to the concrete below.

Auralex makes a drum platform designed to decouple the drums from the structure. http://www.auralex.com/product/hoverdeck/  It’s not a magic bullet by any means, but can be the difference in how many neighbors you share your rehearsal with.

Publishing early to help a friend.  More to come.

If you have questions, I would be glad to try to help.