©THEBRIGHT EXAM STUDY SOLUTIONS 8/27/2024 12:01 PM
AVIXA CTS-D: Human Perception of Sound
Exam Study Guide.
Logarithm - answer✔✔is the exponent of base 10 that equals the value of a number
Decibel - answer✔✔describes a base-ten logarithmic relationship of a power ratio between two
numbers.
-It uses a logarithmic scale to describe ratios with a very large range of values that can vary over
several orders of magnitude.
-It is also used for quantifying differences in voltage, distance and sound pressure as they relate
to power.
Decibels can measure what type of values? - answer✔✔Distance, Power, Pressure, or Voltage
Pascal - answer✔✔SI Unit for Pressure
Decibel Formula for Power - answer✔✔dB = 10 * log (P1 / Pr)
Where:
dB = The change in decibels
P1 = The new or measured power measurement
Pr = The original or reference power measurement
if result is positive, the result is an increase, or gain. If it is negative, the result is a decrease, or
loss.
Decibel Formula for Distance - answer✔✔dB = 20 * log (D1 / D2)
Where:
, ©THEBRIGHT EXAM STUDY SOLUTIONS 8/27/2024 12:01 PM
dB = The change in decibels
D1 = The original or reference distance
D2 = The new or measured distance
This as the same as:
db= 10 * log (D1²/D²)
Decibel Formula for Voltage - answer✔✔dB = 20 * log (V1 / Vr)
Where:
dB = The change in decibels
V1 = The new or measured voltage
Vr = The original or reference voltage
db = 10 * log (V1²/V2²)
Reference Level Sound Pressure: 0 dB SPL in Pascals - answer✔✔.00002 Pa / 2x10^-5 Pa / .02
mPa @ 1kHz
Reference Level Voltage (Consumer Electronics): 0dBV in Volts - answer✔✔1 V
Reference Level Voltage (pro AV): 0 dBu in Volts - answer✔✔0.775 V
Reference Level Power: 0 dBW in Watts - answer✔✔1W
Reference Level Power: 0 dBM in milliwatts - answer✔✔1 mW / .001W
Explain negative decibel values - answer✔✔measurement just means "less than before," or in
this case, "less than the reference level. It does not mean the basic unit it represents has a
negative value
Hearing Damage Threshold in dB - answer✔✔120 - 140 dB
Pro-Audio line level in dBu and volts - answer✔✔+4dBu and 1.23 Volts
Consumer Line Level in dBV and milllivolts - answer✔✔-10dBV, 316 mV
AVIXA CTS-D: Human Perception of Sound
Exam Study Guide.
Logarithm - answer✔✔is the exponent of base 10 that equals the value of a number
Decibel - answer✔✔describes a base-ten logarithmic relationship of a power ratio between two
numbers.
-It uses a logarithmic scale to describe ratios with a very large range of values that can vary over
several orders of magnitude.
-It is also used for quantifying differences in voltage, distance and sound pressure as they relate
to power.
Decibels can measure what type of values? - answer✔✔Distance, Power, Pressure, or Voltage
Pascal - answer✔✔SI Unit for Pressure
Decibel Formula for Power - answer✔✔dB = 10 * log (P1 / Pr)
Where:
dB = The change in decibels
P1 = The new or measured power measurement
Pr = The original or reference power measurement
if result is positive, the result is an increase, or gain. If it is negative, the result is a decrease, or
loss.
Decibel Formula for Distance - answer✔✔dB = 20 * log (D1 / D2)
Where:
, ©THEBRIGHT EXAM STUDY SOLUTIONS 8/27/2024 12:01 PM
dB = The change in decibels
D1 = The original or reference distance
D2 = The new or measured distance
This as the same as:
db= 10 * log (D1²/D²)
Decibel Formula for Voltage - answer✔✔dB = 20 * log (V1 / Vr)
Where:
dB = The change in decibels
V1 = The new or measured voltage
Vr = The original or reference voltage
db = 10 * log (V1²/V2²)
Reference Level Sound Pressure: 0 dB SPL in Pascals - answer✔✔.00002 Pa / 2x10^-5 Pa / .02
mPa @ 1kHz
Reference Level Voltage (Consumer Electronics): 0dBV in Volts - answer✔✔1 V
Reference Level Voltage (pro AV): 0 dBu in Volts - answer✔✔0.775 V
Reference Level Power: 0 dBW in Watts - answer✔✔1W
Reference Level Power: 0 dBM in milliwatts - answer✔✔1 mW / .001W
Explain negative decibel values - answer✔✔measurement just means "less than before," or in
this case, "less than the reference level. It does not mean the basic unit it represents has a
negative value
Hearing Damage Threshold in dB - answer✔✔120 - 140 dB
Pro-Audio line level in dBu and volts - answer✔✔+4dBu and 1.23 Volts
Consumer Line Level in dBV and milllivolts - answer✔✔-10dBV, 316 mV
