Studio Acoustics Part 1

Studio Acoustics Part 1: An Overview of Room

Issues

In this new mini-series, Joe Albano demystifies the science of studio acoustics.

Part 1 deals with common room issues and applies to all of us who have home or

pro recording and mixing studio spaces.

So much of the effort we put into setting up our studio spacesbig or smallis

focused on gear, but its important to remember the one component that

probably has the biggest effect on the sound quality of the work we dothe room

itself. Theres no getting around it, everything we do during tracking, mixing,

and mastering, is based on what we hear during sessions in our control room

spaces, along with the effect the live recording space has on the sound we

capture with our mics.

The Acoustic Conundrum

If you cant trust the room you work in to give you an accurate idea of what your

recordings and mixes really sound like, then you cant really trust your choices.

Will my mix sound this way in other listening environments, or am I reacting to

some specific room tone, and making tweaks that will sound dubious, at best, in

other listening spaces? Will the ambience in that vocal recording, that seems to

be helping it blend in the mix, end up making it sound too distant, when the mix

is heard in a space with a drier acoustic?

These are the kinds of issues that can trip up even experienced engineers and

producers. So, to get the best results in all your studio endeavors, it pays to

spend some time analyzing your space, and, as much as possible, optimizing it

for the most neutral, most reliable sound quality it can provide.

A typical small studio, with various simple (budget-conscious) room treatments.

But Im Just a Musician

Of course, this is easier said than done! Many room issues may require highly

technical analysis, with test gear thats beyond the reach of the average small or

home studio operator, and sometimes the best solutions for room problems can

involve fairly major construction, an option that probably isnt available to most

people. That said, however, there are still quite a few steps that anyone can take

to improve the sound quality and, most importantly, the linearity of their

http://macprovid.vo.llnwd.net/o43/hub/media/1130/10073/Fig_1.png

working environment, and while you may not be able to fine-tune your personal

recording/mixing space to the level that high-end studios do, you can still

eliminate many of the most vexing flaws, and shape your environment to be

much more amenable to the creation of good recordings and mixes, that travel

well, and stand up to even the best studio efforts!

There are quite a few areas, when it comes to the behavior of sound waves in a

studio space, that can be addressed, even with a minimal budget, as long as you

have the necessary familiarity with the way sound waves interact with room

surfacesthe basic physics of audio in enclosed spaces. Now, as soon as I say

Physics, I know a lot of people immediately start to glaze overhey, I just

wanted to do music, not science! But then, everything we do involves sound and

electronics, and you dont need an advanced degree in acoustics or electrical

engineering to understand enough to be able to make some degree of beneficial

change to the sound and layout of your studio space. And believe me, its worth

the effortyour mixes will thank you, your clients will thank you, and therell be

that much less standing in the way of doing your best work!

Room Issues

So what are the problems that smaller studioscontrol rooms and recording

spacesare likely to have? Ill be talking about some of the most common of

these in an upcoming series of articleshow to identify and quantify room issues

and possible solutions, with an emphasis on solutions for the budget-challenged.

By way of introduction to the topic, here are, in no particular order, some of the

room issues that typically need to be addressed in studio spaces, and that Ill be

covering in this series..

The Low End

Low Frequency issuesStanding Waves, aka Room Modes: Low frequency

reflections tend to build up unevenly, especially in smaller rooms, causing

listeners to hear more or less bass, at certain frequencies, and in certain spots in

the room.

A graph of some of the Standing Waves (Room Modes) in a small studio Control

Room.

This is a big one, maybe the most common cause of mixes that dont sound quite

right anywhere but the room they were made in. In a live recording area, Room

Modes might cause an audio recording itself to end up either too bass-shy, or too

bass-heavy, requiring extra effort to fix the problem in the mix. Even worse, in

the control room, Standing Waves in the room can fool a mixer into adding or

removing bass to solve a problem that exists only in that room, with EQ choices

that will only sound good only in that room, and will likely make the mix sound

worse, even to the point of being virtually unlistenable, in other spaces that dont

share the same specific low-end flaws! Standing Waves are also one of the

toughest nuts to crack, in terms of solutions, because the best fixes can

sometimes involve changes to the size and/or shape of the room itself, or the use

of add-on structures that can eat up a bit of the rooms square footage, and may

be a tad pricey, if youre not a big DIYer.


Reflect on This

Mid & High-Frequency Reflections: Problems here can manifest themselves in

several ways.

Phase Cancellations, or Comb Filtering: Sound waves reflecting off room

surfaces can muddy up a space. When reflected sound waves combine with the

direct sound wavethe wave going straight from the speaker to the listeners

earsafter a very slight delay, cancellations and reinforcements will occur due to

phase differencesvery small timing differencesbetween the direct and

reflected waves. This will result in changes to the balance of Harmonics and

Overtones in the wavesthe components of a sound wave that give a particular

instrument or voice its tonal character. This is known as Comb Filtering, and a

little of it is a normal, natural part of the overall sound field in every enclosed

space, and is generally a good thing.

The path of a short reflection, combined with the original wavem, and a graph of

the altered, Comb-Filtered response.

But too much of it, or phase interference that causes too great a tonal change,

can make music sound thin, nasal, or edgy, and mixes can lose clarityinstead of

clearly hearing what all the parts in a busy arrangement are doing, everything

can start to sound kind of washed-out and indistinct, making it difficult to

achieve a good mix.

Hello, hello, hello


EchoesSlap Echoes, or Flutter Echoes: Multiple reflections tend to blend

together for a smooth sound quality that can enhance both recording and mixing

(see the next paragraph), but reflections with longer delay times, especially

excessively strong, isolated reflectionsechoeswill likely be detrimental at

every stage of the process, and need to be physically eliminated by appropriate

room treatments.

The path of a Flutter Echo, in a room with parallel surfaces.

Eliminating problematic mid/high-frequency reflections, both short and long, is

a little easier to accomplish than dealing with low frequencies, but, again, you

need to know what kind of treatment to apply, and where and how much to use,

or youll just end up substituting one problem for another.

Room Tone

Ambience: Ambience is the term used to refer to the overall liveness of a room

the result of a normal, healthy balance of direct sound and multiple reflections in

a typical enclosed space. Here, the key is to get that balance just righttoo much

ambience might obscure the effects you may be applying to a mix, or make


recordings sound too distant and hollow. Too little ambiencetoo dry a space,

like some of the heavily-padded vocal booths some people havewont support

the sound the performer makes, leading to their voice or instrument sounding

overly dry and weak, and forcing them to work harder to generate a rich, full

tone, often resulting in either strained or lackluster performances. And even a

control room, where you dont want the room tone to get in the way of hearing

whats in the actual tracks themselves, still needs an appropriate amount of

liveness, otherwise it wont be a suitable environment to work in, and you wont

get mixes that, again, will travel well to other listening spaces. There are a

variety of approaches to achieving a good ambient balancedifferent for live

recording spaces and control rooms, both of which Ill touch on as I go through

these areas.

Top - A room with potentially excessive ambience (reflections); Bottom - the

room with various acoustic treatments.

Problems to Solutions

Ive laid out a number of issues here, that typically bedevil small studiosthe

first step in dealing with acoustic problems is to be aware of what youre up

against. Over the next several articles in this series, Ill describe each of these in

more detailwhat causes the problem, from a physical standpoint; how to


measure or identify the effect in a particular room, and locate any specific

problem areas; and what sort of treatment(s) can be applied to deal with it,

again, with an eye toward minimum-cost solutions.

Ill start out next time with the issue thats probably #1 on most small studio hit

listsLow Frequency Standing Waves / Room Modes. See you next time

Documents

Studio Acoustics Part 1