Volume 6, Number 4, December, 1998 - Noise News International

518584 3754; FAX: +1 5185809525;
e-mail: info@mstrtech.com. Circle
Reader Service Number 58.
Real Time Meteorological Measurements
to Support Noise Engineering
Projects and Sound Propagation
Studies. AeroVironment Environmental
Services Inc. (AVES) of Monrovia, California,
provides measurements of temperature,
humidity, and wind profiles to
noise control engineering firms using
balloon borne (tethered or free flight) instrumentation
and acoustic measurement
systems (Doppler Acoustic Sounders).
AVES is an environmental consulting and
measurements firm who has been in business
since 1972. AVES has manufactured
a comilete line of Doppler Acoustic
Sounders (acoustic wind profilers) since
the miJ-1970s. The company also has
airsoncle and tethers onde systems that
have been used to provide model inputs to
sound propagation models during the
testing and validation stages. Recently
AVES provided continuous measurements
of wind speed, wind direction, and
temperature at four altitudes (ground
level, ]0 meters, 50 meters and 100 meters)
using a tethered balloon system.
These data were the data inputs for a
sound propagation model that was being
validated by a client.
For further information, call or write
Alexander N. Barnett, AeroVironment
Environmental Services Inc., 222 Huntington
Drive, Suite 200, Monrovia, California
91016. Telephone: +1 626 357
9983; FAX: +1 626 359 9628; e-mail:
barneu@aerovironment.com. Circle
Reader Service Number 59.
Oticon Introduces First Digital
Hearing Aid for Hard-to-Treat Noise­
Induced Hearing Loss. Oticon has introduced
DigiFocus SKITM. An estimated
10 to 20 percent of the hearing impaired
population suffer from noise-induced
hearing loss and should benefit from this
new digital technology.
The proprietary technology and software
of DigiFocus SKI is said to enable
the hearing care professionals to assist
patients where they need it in the least intrusive
way. DigiFocus SKI features a fitting
rationale that is specifically
developed for the patient group with
1998 December
more than 25dB/octave slope hearing
losses starting at 1kHz or above.
At low frequencies, DigiFocus SKI
applies syllabic compression. In the critical
transition zone, where hearing begins
to drop off rapidly, DigiFocus SKI automatically
finds the appropriate crossover
frequency and switches to a linear amplification
approach. In high frequencies,
the instrument applies compression limiting
with reduced gain rules in order to
assist in noisy situations and avoid over-
loading the more severely damaged part
of the auditory system.
The instrument offers an algorithm
featuring a new loudness model, new
gain formulas, new vent recommendations,
seven-band frequency shaping for
maximum clarity and comfort, syllabic
compression in the lower frequencies, automatic
crossover frequency, and
high-frequency compression limiting.
Custom versions of DigiFocus SKI are
as small, discrete in-the-ear instruments.
a smaller footprint
a more cost-effective design
on-hazardous /non-flammable wedges
Combining 25 years' experience in the design and
construction ofmodular acoustic panels with the
expertise of an NVLAP accredited testing facility
has re-invented the anechoic
chamber, developing a system that meets industry
needs better than any such testing chamber has
before. The revolutionary, patent pending
chamber incorporates anechoic wedge elements
within uniquely effective acoustic panels that have
earned Acoustic Systems its reputation as a
leader in modular sound isolation. This innovative
design produces an anechoic chamber that performs
better than the old-style models while costing less to
acquire, install and maintain. It requires less exterior
space relative to working interior space and utilizes
a uredqe con~truction tha~ eliminates t~edifficultj~:: :
ossocloted with metal or fiberglass deslgns.===::::::
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