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General Warnings - ReSound Aventa 3 User Manual

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General Warnings

• When connected, the Aventa Fitting Software controls the acoustic amplification levels in a hearing instrument . In
some acoustic environments, over amplification can cause discomfort and damage to the patients hearing .
• The Fitting System provides initial default amplification settings based on hearing threshold levels . These default
settings could be higher than stable levels and cause feedback when amplification is first applied .
• The Fitting System initiates the feedback calibration procedure . Feedback calibration uses broadband noise to
measure the amount of sound leaking from the hearing instrument . The output level is designed to be on the
boarder of "uncomfortable" level based on hearing threshold level at a specific frequency . The sound will be
ramped up in volume and cease when the calibration data is received . It is possible for the level to exceed a pa-
tients comfort level, but it needs to be determined if it can obtain hazardous risk levels .
• The Fitting System initiates feedback calibration to measure the receiver to microphone transfer function . This is
used primarily by the hearing instrument to manage feedback suppression but it is also used to display the limits
of stable gain .
• The maximum stable gain estimates are based on feedback calibration data, the presence of active feedback sup-
pression, and a headroom estimate . The headroom value is meant to be conservative however the presence of
directionality has shown to give inaccurate estimates of max . stable gain . The risk is that, under some situations,
the Fitting System could show that the hearing instrument is stable when it is actually close to unstable and in risk
of feedback .
• If feedback calibration has not been performed during fitting the Max Stable Gain is not known and the device
could cause feedback without warning .
• The Fitting System uses the Audiogram+ algorithm to interpret audio gram data for determining optimal gain set-
tings . The parameter used is "first time user" . This may give a less than optimal initial fitting but should not pose
a safety risk . The algorithm has been independently validated with the specification and verified to be consistent
with Fitting Software .
• The Fitting System uses feedback calibration measurements to compute Max Stable Gain values . These values
are an estimate of the amount of gain that can be safely applied to a hearing instrument be fore it begins to cause
feedback . There is a warning when this gain is reached, and the over gain values are highlighted with bold, red
text . The safety margins give a "close" approximation of the actual feed back border . However, it's an estimation
and feedback can occur before the warning is given . Sustained feedback on high power devices can damage
residual hearing .
• Warning to hearing care practitioners: Special care should be exercised in selecting and fitting hearing instrument(s)
whose maximum sound pressure level exceeds 132 dB SPL with an IEC 60711: 1981 occluded ear simulator, be-
cause there may be a risk of impairing the remaining hearing of the hearing instrument user .
• Warning to hearing care practitioners: Special care should be exercised in selecting and fitting hearing instrument(s)
utilizing Tinnitus Sound Generator . The maximum output of the tinnitus sound generator feature falls into the range
that can cause hearing loss according to OSHA regulations . For further details please consult the user guide of
the relevant hearing instrument that includes the Tinnitus Sound Generator feature . In accordance with NIOSH
recommendations the user should not use the sound generator for more than eight (8) hours a day when this is set
to a level of 85db SPL or above . When the sound generator is set to levels of 90db SPL or above the user should
not use the sound generator for more than two (2) hours per day . In no case should the sound generator be worn
at uncomfortable levels .
• Children and physically or mentally challenged users will require guardian supervision while wearing the device .
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