Specifications

EAW Smaart 6 Operation Manual
23
Chapter 2: Concepts, Glossary, and Bibliography
This chapter defines the concepts and terminology used in Smaart 6. These definitions
are accurate with regard to Smaart 6 but are not intended to be mathematically compre-
hensive. A bibliography is provided at the end of the chapter for those wishing to pursue
a more rigorous study of these topics.
2.1 Concepts
2.1.1 Decibels
The decibel (dB) is a unit that expresses the logarithmic ratio between two amounts of
power, voltage, or any two values that differ over a wide range. Logarithmic scales are
useful in acoustics and audio because of the wide range of human hearing sensitivity to
sound pressure and frequencies. Most audio measurements based on voltage or sound
pressure are expressed in decibels. The power and voltage ratios in Table 2-1 illustrate
why a logarithmic scale is needed.
Table 2-1 Power and voltage ratios as decibels
Note that 60 dB, about half the decibel range of human hearing, represents a Power Ratio
of one million to one. A frequent point of confusion regarding decibels is the meaning
of 0 dB. For SmaartLive’s purposes, 0 dB means:
• In a Frequency Response measurement, dB values represent the difference
between the reference and measurement input signals. When the energy in both
input signals at a given frequency is the same, the magnitude response is 0 dB
at that frequency.
Power
Ratio
dB
Voltage
Ratio
dB
.1 -10 .1 -20
.5 -3 .5 -6
10 1 1
23 2 6
10 10 10 20
100 20 100 40
1,000 30 1,000 60
10,000 40 10,000 80
100,000 50 100,000 100
1,000,000 60 1,000,000 120