Recording - January 2018 - 62

STUDIO 101

PART 1

The Essence
of Sound

Readers of our very first issue (October 1987) will remember an article called "Studio 101," an introduction to the (at the
time) modern personal recording studio. Things have changed a lot since then, and I'm proud to present the first in a monthly
series of articles on the subject by my colleague Darwin Grosse. Darwin is a musician, engineer, sound library composer,
computer software guru, and famed music interviewer, with over 200 episodes in his Art+Music+Technology podcast, which
you can check out at artmusictech.libsyn.com.
In this series, Darwin will bring a modern touch to educating readers on the basics of sound and recorded music. The aim
will be to embrace modern tools and get confident with them rather than poking at them suspiciously and expecting them to
bite. I've enjoyed working with Darwin on starting this series, and I'm sure you'll enjoy learning from him as we go.-MM
BY DARWIN GROSSE

elcome to Studio 101! I'm really excited to
be working on this project; it's the sort of
thing that can help you if you are new to the
field, but can also help grizzled veterans willing to embrace
their "Beginner's Mind." We are going to start with some
basic information on sound, signals, and digital storage,
then move into the more practical concepts of recording,
monitoring, mixing, and mastering your work. We'll also
dive into deeper information on both hardware and software processors, and dissect some of the issues that you
might run into with your recording practice.
Let's get started by looking at the elements of our world:
the nature of sound. The whole point of recording is capturing, reproducing and tweaking sound, so it is fundamental knowledge for us. Once we understand the
essence of sound, we will more easily be able to understand
the process of converting it into electrical signals, which is
a key component of the recording process.

Sound elements
When we talk about sound, we are going to be talking about
acoustic information transmitted through the air, getting captured
by our ears, and causing us to hear and understand voices, music,
and noise. This information exists as pressure waves, where air
particles are compressed and expanded by the movement of a
sound source-something that is easily seen if you watch a loudspeaker cone move when you play some music. As sound is
being reproduced by a speaker, it moves backwards and forward,
pushing and pulling on the air, and making the compressed and
expanded waves necessary to activate our perception of sound.
However, we seldom think about sound as pressure waves
(unless we've just walked out of a Metallica concert). When
we talk about sound, we most often talk about three major
components that we can quantify: amplitude, frequency, and
timbre. Each of these has some unique qualities-as well as
ways to be measured-so we need to take a closer look.
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RECORDING January 2018

Amplitude
When we talk about amplitude, we are talking about the
volume level of a sound. Whether whisper-quiet or jackhammer-loud, the most common descriptor of a sound is its
volume. For audio, sound is measured in decibels (abbreviated
dB). This is a logarithmic scale: an increase in level by 6 dB
is actually a doubling of the volume, 12 dB is quadrupling,
etc. We need to use logarithms for this application because
the range of sound levels we can hear is so great, from the
tiniest whisper to a bomb exploding.
Examples of sound pressure levels (dB SPL) that you might
encounter: a quiet field might register at 30 dB, while a
loud garbage disposal can hit 80 dB. A chain saw? 120
dB or so. Once you hit that 120 dB level, things get
painful; in fact, prolonged exposure at 90 dB or greater is
likely to cause long-term damage to your ears. Therefore,
paying attention to the SPL of your surroundings-and your
studio-is important.
To be technically correct and meaningful, a measurement
in dB is actually a relative number measured against some
reference point. For example, when we talk about these
amplitude measurements in dB SPL, we are using a reference
level of the threshold of human hearing (0 dB SPL) and moving
upward. There are other dB references that we'll see in use in
the studio: dBu for levels relative to standard VU meter measurements, dBFS for levels of digital signals relative to "digital
zero", the loudest a signal can be before clipping, or dBm
for the power level of a sound on a standard electrical load.
These different references aren't particularly important right
now, but when we encounter them in the future, make sure you
know which one is being used.

Frequency
The next most common description of a sound would be its
frequency. Is it high (like a bird song), or is it low (like a tuba)?
Is it stable (like a bell) or wobbling (like a police siren)? Pitch

http://artmusictech.libsyn.com

Table of Contents for the Digital Edition of Recording - January 2018