WinMLS 2000 - Summary of
Specifications
Measurement specifications: modes are MLS (advanced
settings available), sinusoid, user defined and scope. Auto-name generator for
saving, 1-24 channels measurement with sampling rates up to 96 kHz (sound card
dependent). Influence of measurement system may be subtracted, initial time
delay can be measured exactly, pre and post-filtering is supported for
increasing signal-to-noise ratio. Sound card calibration is supported. All the
measurement settings are saved in a “measurement” setup file.
Post-processing specifications: Plot types supported
are Time data (impulse response), step response, energy-time curve, schroeder
curve, frequency response/spectrum, phase response, group delay, waterfall,
room acoustics parameters such as reverberation time. All settings for all
these plot-types are accessed by double-clicking in the plot. Two plot-types
can be viewed simultaneously, so you can change the windowing of the impulse
response and immediately see how it affects the frequency response. No
limitation in number of curves in a plot, auto-refreshing, solo of active
measurement curve. All the post-processing settings are saved in a
“post-processing” setup file.
Industrial application: Versatile tool in active noise
control and audio product development
Silence International
uses WinMLS 2000
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Silence International is a young Norwegian
company specializing in active noise control. Their first product is the Silent
Zone, an active system for improvement of sound quality for diesel locomotive
engineers. The product is developed in cooperation with the Norwegian State
Railway and SINTEF Telecom and Informatics. See www.silence.no for further information.
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WinMLS has been used in various stages of
the Silent Zone product development: Microphone and loudspeaker exploration,
electronics testing, verification of real-time digital signal processing systems,
measurement of local electroacoustic responses in the assembled system, measurement
of room impulse responses in the locomotive cab, and ve
rification
of system performance.
·
Silence International has been using WinMLS
for more than 2 years, and it has been a crucial tool says the project manager:
”Its high resolution, repeatability, and flexibility are important to us.
The ability to control measurements from Matlab makes it possible to automate
special procedures, and to control measurement quality. The two-channel capability
is important for measurements requiring an external reference, like microphone
transfer functions. And above all, the portability makes field measurements
in demanding environments a breeze. All in all the system has an amazing performance,
we have been measuring microphone and loudspeaker responses down to well below
10Hz, made laser measurements of loudspeaker cone excursion, and captured
high quality room responses in noisy locomotive workshops. WinMLS has provided
us with the data necessary to produce accurate anti-noise and high quality
audio systems. We will continue making use of WinMLS in test and verification
during all stages of Silent Zone production.
Powerful Room Acoustics Parameter Calculations
Room Acoustics Parameter
Calculations for WinMLS 2000
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As a room acoustician you can with this product perform your standard
acoustical measurements very user friendly, with high quality and at low cost.
The powerful measuring method is used by professional acousticans, both
researchers and consultants.
·
Measure the impulse responses of rooms, and calculate the room
acoustical parameters. All you need, in addition to your normal set of
transducers and amplifiers, is a PC and an inexpensive standard sound card (not
all sound cards are suitable, we provide a list of tested sound cards).
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The room acoustics post processing module for WinMLS calculates
parameters according to the ISO 3382 (1997) standard: Reverberation time, early
decay time, early-to-late indices, definition, centre time, strength, speech
transmission index, rapid speech transmission index, and the stage acoustics
parameter support. Two channel options like lateral fraction and inter-aural
crosscorrelation are also provided. In addition, the new parameter late lateral
strength is included.
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Noise detection and compensation is included for all parameters, and the
calculations are tested against international benchmarks.
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The toolbox is developed by dr. Johan L. Nielsen, who has for several
years been working with room acoustics both at the Norwegian Institute of
Technology and at the University of Auckland, New Zealand. He has published
papers on measurement techniques and accuracy of room acoustical parameters. He
is currently development manager at Silence International in Oslo, Norway.
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For questions, more information, or for signing up as a beta tester,
please contact roomacoustics@winmls.com.
Room Acoustics Parameter Calculations
Specifications
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Room impulse response post processing module for WinMLS
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Reverberation time in octave and 1/3-octave bands according to the ISO
3382 (1997) standard
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Other room acoustical parameters in octave bands according to the ISO
3382 (1997) standard:
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Early decay time, clarity, definition, centre time, strength, and the
stage parameter support
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Calculation support for anechoic source calibration for strength
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Dual channel parameters like lateral fraction, late lateral strength and
inter-aural crosscorrelation (early, late and total)
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Speech transmission index and rapid speech transmission index, including
octave band corrections for background noise
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Digital filtering in octave and 1/3-octave bands according to the IEC
1260 (1995) standard
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Backwards filtering for 1/3-octave band reverberation time improved
accuracy
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Parameters also calculated in double-octaves or without filtering
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Noise detection and compensation included for all parameters
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Data can be exported, or plotted using WinMLS powerful graphics