Chapter 4 Flashcards
What is dynamic range ?
The difference, in decibels, between the loudest and the quietest portion of a program.
True or False
Every sound system has an inherent noise floor
True
What is the dynamic range formula?
= (Peak Level) - (Noise Floor)
What is the unit of measurement for Dynamic range?
dB
What is nominal program level?
The average electronic line level corresponding to an average sound level at the microphone
What is the unit of measurement of headroom?
dB
What is the dynamic range of a sound system
is equal to?
the difference between the peak output level of the system and the electro-acoustic noise floor
True or False
dynamic range can be expressed in dB SPL, dBm, dBu or any other specifically referenced dB value
dynamic range is nearly always specified in dB, and should never be expressed in dB SPL, dBm, dBu or any other specifically referenced dB value
What is headroom?
The difference between the nominal and the highest (peak) levels in a program
What is Signal-To-Noise Ratio?
represents the difference between the nominal level and the noise floor
True or False
you can always add the S/N ratio to the headroom and come up with the dynamic range.
False
You can’t
Headroom requirements change with ____________________________ and ________________________________
the nature of the program material and the purpose for which the sound system is operated
What is the result when the dynamic range of the
program material exceeds the dynamic range capability of the sound system?
a) Program peaks will be distorted due to clipping and/or loudspeaker break-up, and/or
b) Quiet passages will not be heard because they will be below the electrical and/or acoustic noise floor
Why is headroom important?
tells us something about the ability of the
sound system to handle loud program peaks
Give the formula for headroom
= (Peak Level) - (Nominal Level)
Measure the some new electronics and found that they have an electronic noise floor of -56 dBu (1.23 millivolts), and a peak output level of +18 dBu (6.16 volts). What is the dynamic range of this newly assembled system?
dynamic range…
=(Peak Level) - (Noise Floor)
= +18 dBu - (-56 dBu)
=74dB
A sound system’s dynamic range can
be increased by ________________, or _____________________
increasing the maximum sound level capability or by making the environment quieter.
What is the importance of the Signal-To-Noise Ratio?
It is shown so you can see how this specification is related to dynamic range and headroom.
What are the side effects of compression?
such as making quiet breath sounds louder, creating a
pumping effect in some cases, and increasing the distortion of low frequency signals
Describe limiters
Some devices permit compression to be applied above a set threshold, and the compression ratio to be very high
What would occur if the threshold were set lower,
or the compression ratio to a higher value?
then more dynamic range would be conserved, and the overall signal level at the compressor output could be increased to stay above the console’s noise floor.
Describe the purpose of a compander noise reduction system
allows the original program dynamics to be maintained throughout the recording and playback process by
compressing the program dynamic range before it goes onto the tape
What is the purpose of a compressor?
By setting the compressor for a relatively gentle compression ratio of 2:1, every dB of input level change will result in half a dB of output level change
What determines the choice of headroom figure?
depends on the type of program material, the application, and the available budget for amplifiers
