Digital Sound & Music: Concepts, Applications, & Science, Chapter 1, last updated 6/25/2013
workstation experiences a glitch, it's usually due to some other task the computer is trying to
perform at the same time, such as checking for a software update, running a virus scan, or
refreshing a Facebook page. Dedicated hardware solutions like the one shown in Figure 1.41
have only one task, and they can perform that task very reliably.
Figure 1.41 A dedicated digital signal processor
Other hardware devices you might include with your system would be an analog or
digital mixing console or dedicated hardware processing units such as equalizers, compressors,
and reverberation processors. These dedicated processing units can be helpful in situations where
you're working with live sound reinforcement and can‟t afford the latency that comes with
completely software-based solutions. Some people simply prefer the sound of a particular analog
processing unit and use it in place of more convenient software plug-ins. There may also be
dedicated processing units that are calibrated in a way that's difficult to emulate in a software
plug-in. One example of this is the Dolby LM100 loudness meter shown in Figure 1.42. Many
television stations require programming that complies with certain loudness levels corresponding
to this specific hardware device. Though some attempts have been made to emulate the functions
of this device in a software plug-in, many audio engineers working in broadcasting still use this
dedicated hardware device to ensure their programming is in compliance with regulations.
Figure 1.42 Dolby LM100 loudness meter.
Mixers are an important part of any sound arsenal. Audio mixing is the process of combining
multiple sounds, adjusting their levels and balance individually, dividing the sounds into one or
more output channels, and either saving a permanent copy of the resulting sound or playing the
sound live through loudspeakers. From this definition you can see that mixing can be done live,
"on the fly," as sound is being produced, or it can be done off-line, as a post-production step
applied to recorded sound or music.
Mixers can analog or digital. Digital mixers can be hardware or software. Picture first a
live sound engineer working at an analog mixer like the one shown in Figure 1.43. His job is to
use the vertical sliders (called faders) to adjust the amplitudes of the input channels, possibly
turn other knobs to apply EQ, and send the resulting audio to the chosen output channels. He
may also add dynamics processing and special effects by means of an external processor inserted
in the processing chain. A digital mixer is used in essentially the same way. In fact, the physical
layout often looks remarkably similar as well. The controls of digital mixers tend to be modeled