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Acoustical Studies I
3 forms of particle motion?
- Cylindrical
- Transverse
- Longitudinal
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Acoustical Studies I
Formula to calculate speed of sound knowing only the temperature?
c = 49√(459.4 + degrees F)
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Acoustical Studies I
How does temp affect speed of sound?
- Temp increases, so does speed of sound
- Temp decreases, so does speed of sound
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What is wavelength?
The distance a wave travels to complete one cycle
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Acoustical Studies I
How do you calculate wavelength?
λ = 1130/Hz
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Acoustical Studies I
How do you calculate octave relationships?
- 2:1 ratio
- Doubling of halving
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Acoustical Studies I
How do you calculate harmonics?
Multipliers of the fundamental
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Acoustical Studies I
Formula to calculate a range of octaves?
2^n = ƒH/ƒL
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EASE 1
EASE was developed by?
Wolfgang Anhert
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EASE 1
Types of room input methods other than vertex by vertex?
- Extrude
- Insert 3D shape
- Load a prototype
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EASE 1
5 types of 3D shapes you can insert?
- Cylinder
- Cuboid
- Cupola
- Cone
- Pyramid
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EASE 1
Interior surfaces are what color?
Yellow
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EASE 1
Save & Apply hotkey?
F6
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EASE 1
Most rooms modeled in negative axis. Why?
That's the way speakers are facing when inserted
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EASE 1
Command for cutting a face into 2 faces?
Fixed cut
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EASE 1
Delete Unattached Vertices hotkey?
Ctrl+Shift+F12
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EASE 1
When adding floor to ceiling columns, you must:
Is coat of?
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EASE 1
What are some of the prototypes available?
- Church
- Stadium
- Amphitheater
- Gothic dome
- Tricue
- Station
- Redoubt
- Theater
- Shell
- Multipurpose
- Auditory
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Intro to Measurement Systems
Main reasons for sound system measurement?
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Intro to Measurement Systems
5 basic test signals
- White Noise
- Pink Noise
- Broadband Pulse
- Shaped Noise
- Sine Waves
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Intro to Measurement Systems
What is white noise?
Equal energy / frequency
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Intro to Measurement Systems
What is pink noise?
Equal energy / octave
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Intro to Measurement Systems
2 most common weighting curves for SPL meters?
A & C
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Intro to Measurement Systems
Dimension RTA is missing?
Time
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Intro to Measurement Systems
What is Fourier Transform?
Mathematical calculation converts: (amplitude vs time) into (amplitude vs frequency)
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Intro to Measurement Systems
What measurement systems use FFTs?
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Intro to Measurement Systems
What does TEF stand for?
Time Energy Frequency
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Intro to Measurement Systems
What does MLS stand for?
Maximum Length Sequence
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Polarity-Phase
Define polarity.
A source or signal is either pushing positive or negative
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Polarity-Phase
Phase in 4 words?
Frequency Dependent Time Delay
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Polarity-Phase
3 ways to reverse polarity?
- Swap pins 2 & 3 on cable
- reverse speaker wiring
- Polarity switch or settings (console)
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Polarity-Phase
Two signals of equal amplitude at 0º offset will result in?
6 dB of coupling
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Polarity-Phase
Two signals of equal amplitude at 180º offset will result in?
Full cancellation
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Polarity-Phase
Two signals at equal amplitude at 120º offset will result in?
Neither cancellation or coupling.
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Polarity-Phase
Trace angled to the left is:
Lagging
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Polarity-Phase
Trace is angled to the right:
Leading
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Polarity-Phase
Trace angled straight up and down is:
Wrapping
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Polarity-Phase
How many milliseconds of delay would each of these speaker drivers require to be in time
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Acoustical Studies II
Advantages of parametric EQ over graphic EQ?
- Adjustable center frequency
- Adjustable bandwidth
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Acoustical Studies II
What is complimentary EQ?
- Creating the opposite in gain
- Matching the bandwidth
- Matching the center frequency
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Acoustical Studies II
What is error in center frequency?
When the center frequency of the anomaly and the center frequency of the correction do not match
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Acoustical Studies II
What is error in bandwidth?
When the bandwidth of the anomaly and the bandwidth of the correction do not match
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Acoustical Studies II
What is comb filtering?
Two signals arriving at different times near equal amplitude causing cancellation of linear frequencies
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Acoustical Studies II
Two independent factors that determine the magnitude and frequency response of comb filtering?
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Acoustical Studies II
Calculate comb filtering?
- f = 1/t
- f - frequency spacing
- t - time offset in ms
- To find 1st null, divide frequency spacing by 2
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Acoustical Studies II
Why is it called comb filtering?
On a linear scale, it looks like the bristles of a comb
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Acoustical Studies II
Actions to reduce comb filtering?
- Gate
- Delay
- Level offset
- High pass filters
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Acoustical Studies II
Why are EQs blamed for poor results when trying to correct comb filtering?
It is a time problem, it cannot be corrected with frequency
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SIM Multi
How many mics can you input to 1 mic switcher?
8
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SIM Multi
Branch Measurement Points?
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SIM Multi
3 frequency responses in a branch?
- Processor
- Speaker + room
- Result
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SIM Multi
What does LONAXN mean?
Left, On Axis, Near
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SIM Multi
ROFFAXF
Right, Off Axis, Far
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SIM Multi
2 variables for a primary mic placement?
- +/- 10º On axis
- Center of listening area
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SIM Multi
What is an inverted processor?
- An upside down EQ
- A cut looks like a boost
- A boost looks like a cut
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SIM Multi
What is Single System?
You are measuring one system at a time, the other systems are muted
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SIM Multi
What is Lobe Study?
The primary system you are studying is muted and you are looking at other systems interacting
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SIMII
What applications is SIM 2.0 Lab Mode used for?
Standalone measurement and research
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SIMII
How do you properly patch for SIM II 2.0 Lab Mode?
Drawing is still on the board
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SIMII
What are the status panels?
Information Windows at the Bottom of the Screen
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SIMII
Data rejected means?
One of the Ports has reached OVERLOAD
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SIMII
2 windows in spectrum mode?
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SIMII
Dimensions in the Delay Finder screen?
Relative Amplitude vs. Time Bottom window 10x magnification of the top window
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SIMII
FIFO stands for?
First In First Out
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SIMII
Hotkeys for trace offset?
( + , - ) keys
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SIMII
Hotkey for Pink Noise
Alt + G
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SIMII
AutoSet Delay hotkey?
F3
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SIM Integration
7 steps to analyze a stereo system?
- 1. Preliminary preparations
- 2. Interfacing SIM with the sound system
- 3. Initial testing
- 4. Testing for harmonic distortion
- 5. Finding the delay offset
- 6. Initial EQ
- 7. Adding the systems together
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SIM Integration
What type of mic is used for acoustic measurement?
Omni-directional
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SIM Integration
What happens when a measurement mic is angled 90º from the source?
At 5kHz and above it starts to roll off
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SIM Integration
Where should secondary mic be placed?
Anywhere in the listening area
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SIM Integration
Typically, where should we not place the measurement mic?
- Near walls or pillars
- Exact center of rooms
- In the aisles (except in some line array situations)
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SIM Integration
When should we use sitting height for the measurement mic position?
In recording studios & for front fills
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SIM Integration
Why does Auto-EQ not work?
Because it's blind
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SIM Integration
What are the initial EQ considerations in a studio?
- The sweet spot must be wide enough for both ears
- Pay close attention to the S/N or Coh
- Only EQ for Low Q problems, don't worry so much about the High Q issues
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SIM Integration
Which company manufactures the Galileo?
Meyer Sound
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SIM Integration
Name of the software used with the Galileo?
Compass
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SIM Integration
What kind of cable is used to connect Galileo to the measurement system?
SIM BUSS cable
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SIM Multi
Label the 6 traces of the following
- 1/processor
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SMAART
Who developed SMAART?
Sam Berkow
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SMAART
Who owns & markets SMAART now?
Rational Acoustics
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SMAART
External hardware needed for SMAART?
- Mic
- Sound card (recommended)
- Cabling/Adapters
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SMAART
Info that must be entered in Spectrum Measurement Config Window?
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SMAART
Info to be entered in Transfer Measurement Window?
The pair of inputs you wish to compare
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SMAART
2 operational modes for SMAART?
- Real time
- Impulse response
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SMAART
2 measurement plot types that can be viewed within SMAART's spectrum mode?
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SMAART
2 measurement plot types that can be viewed in SMAART's transfer mode?
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SMAART
Hotkey to save trace information?
Spacebar
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SMAART
Hotkey to turn generator on/off?
G
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SMAART
What point does SMAART use accumulators rather than FIFO?
Above 16 averages (1 sec, 2 sec, etc)
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Acoustical Studies III
What is reverberation?
Sound that lingers in a room after signal is turned off
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Acoustical Studies III
What is ITG?
Initial Time Gap
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Acoustical Studies III
Who was Wallace C. Sabine?
- Founded field of architectural acoustics
- RT60 formula
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Acoustical Studies III
What is RT60?
The time it take a sound to decay 60 dB
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Acoustical Studies III
Sabine's classic equation for RT60?
RT60 = 0.049V/Sa
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Acoustical Studies III
How to calculate volume?
Volume = LxWxH
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Acoustical Studies III
How do you caculate for S?
Multiply each surface by its two dimensions, then sum the all together
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Acoustical Studies III
formula to calculate the average absorption coefficient of a room
- v= volume
- s= total surface
- -
- a= avg absorption coe
- Sn= surfacd area 1 side
- an= absorption coe 1 side
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Acoustical Studies III
What changes are made to Sabine's equation when calculating for absorption of air?
Add +4mV to the denominator of the Sabine equation
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Acoustical Studies III
Fitzroys equation
dont need to know
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TEF
Who developed Theory of Time Delay Spectrometry?
Richard Heyser
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TEF
Dimensions in an ETC curve?
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TEF
TEF gathers data in which domain?
Frequency
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TEF
It takes _________ to measure time?
Frequency
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TEF
It takes ____________ to measure frequency?
Time
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TEF
Formula to calculate time window?
Bandwidth / Sweep Rate
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TEF
It may be more convenient to set ________ and __________ and let the computer set sweep rate and bandwidth.
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TEF
How to calculate reflection from speaker to floor to microphone?
Pythagorean theorem
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TEF
Why does TEF use 20microPascals for calibration?
Threshold of hearing
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TEF
How does Schroeder Reverse Integration Curve calculate it's data?
From the right side of the screen back to the direct signal
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TEF
Which two harmonics seem to do the most damage to the THD?
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5.1 CAL
How can floating a panel help instead of mounting it?
Absorbs more low frequencies
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5.1 CAL
Most home theaters should have an RT60 of ________ sec from 200Hz to 2kHz.
0.2-0.4
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5.1 CAL
Center speaker should not be more than ______ feet from height of L/R speakers?
2
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5.1 CAL
Two types of rear surround speakers?
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5.1 CAL
Rear surround speakers should be at height of:
At least 6 feet
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5.1 CAL
Good way to determine subwoofer placement to reduce room modes?
Response
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5.1 CAL
Range for loudest sounds of a soundtrack?
105-110dB
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5.1 CAL
Range for quietest background effects on a soundtrack?
50-55dB
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5.1 CAL
3 companies that made 5.1 Audio Toolkit DVD?
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5.1 CAL
What help is a multiplexer when doing 5.1 systems?
it allows multiple microphones to achieve "spatial-averaging"
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SIM III
3 applications can SIM 3 be used for?
- Device analysis
- Speaker analysis
- Room analysis
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SIM III
2 screens in the Freq. Response tab in the Group view?
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SIM III
3 windows in the Band Spectrum screen. What is their significance?
- Console
- Processor
- Microphone
- Representing a single branch
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SIM III
How many different modes available?
- Free Run
- Single System
- Lobe Study
- Combined Systems
- Show
- Mic EQ
- Console Check
- Mic Compare
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SIM III
2 types of Spectrum Analysis views in SIM 3?
- Band spectrum
- Line spectrum
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SIM III
What are the 2 screens shown in the Delay Finder tab?
- Processor amplitude
- Room amplitude
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SIM III
Where do you toggle phantom power for SIM 3?
On the Front Panel tab
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SIM III
Most significant upgrade made to SIM 3 from SIM II?
- Ability to do multi-channel
- CD-ROM
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SIM III
What role does the Galileo processor play in SIM 3 multi-channel?
It acts as the line switcher/processor in the SIM branch
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SIM III
What function of the Galileo processor can be controlled from SIM 3?
Switching outputs (muting/un-muting)
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EASE 2
Which module shows 3D mapping?
EYES
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EASE 2
What symbol used for Acoustic Probe?
XYZ Axis man
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EASE 2
Frequencies used for calculating RASTI?
500 HZ & 2 kHz
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EASE 2
RASTI stands for?
Rapid Articulation Speech Transmission Index
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EASE 2
%ALcons stands for?
Percentage of Articulation Loss of Consonants
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EASE 2
In EASE, what does C stand for?
Clarity
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EASE 2
What does C7 show?
Direct/Reverberant ratio
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EASE 2
What does C50 show?
Speech intelligibility
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EASE 2
What does C80 show?
Music intelligibility
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EASE 2
Module that demonstrates sound transmission and reflections beings
scattered in a room showing SPL loss, orders of reflections and
propagation time of signals?
Ray tracing
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NOISE CONTROL
HVAC?
Heating Ventilation Air Conditioning
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NOISE CONTROL
Male carrier wave is between?
200-350Hz
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NOISE CONTROL
What is normal in presence of noise?
We involuntarily raise our voices due to the noise level
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NOISE CONTROL
What does NCB stand for?
Balanced Noise Criteria
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NOISE CONTROL
Who developed NCB charts?
Dr. Leo Beranek
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NOISE CONTROL
Recommended NCB for classroom?
30-40
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NOISE CONTROL
What is transmission loss?
The loss of sound pressure through various materials
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NOISE CONTROL
Residential constructon: Interior walls made of?
- 2 x 4's
- 16" on center
- 1/2" drywall both sides
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NOISE CONTROL
How many layers of drywall will provide the greatest value for transmission loss?
2
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