SA3286 Datasheet, PDF (6/16 Pages) ON Semiconductor – Pre-configured DSP System

INSPIRIA SA3286
Front
Mic
+
T−coil
MS
switch
(N.O.)
Rear
Mic
+
+
−
Zero Biased
Receiver
CS44
VC
Figure 4. Typical Hearing Instrument Assembly Diagram
INSPIRIA SA3286 Overview
Inspiria SA3286 is a DSP system with adaptive
algorithms that run on an advanced hardware platform. This
hardware platform is a combination of a DSP core and a high
fidelity audio CODEC. The thinSTAX packaging provides
easy integration into a wide range of applications from CIC
to BTE.
The DSP core implements FrontWave directional
processing, programmable filters, adaptive algorithms,
compression, wideband gain, and volume control. The
adaptive algorithms include Adaptive Noise Reduction,
Adaptive Feedback Cancellation and Automatic Adaptive
Directional Microphones.
The Adaptive Noise Reduction reduces audible noise in a
low distortion manner while preserving perceived speech
levels. The Adaptive Feedback Canceller reduces acoustic
feedback while offering robust performance against pure
tones. The Adaptive Directional Microphone (ADM)
algorithm automatically reduces the level of sound sources
that originate from behind or from the side of the
hearing−aid wearer without affecting sounds from the front.
Additionally, the Automatic Adaptive Directional
Microphones algorithm automatically reduces current by
turning off the second input channel if it is not needed.
The Inspiria SA3286 iLog 2.0 Datalogging feature
records various parameters every 4 seconds to 60 minutes
(programmable) during use of the device. Once these
parameter values are read from the device, they can be used
to counsel the user and fine tune the fitting.
iSceneDetect 1.0 is the Inspiria SA3286’s classification
algorithm that senses the users environment and
automatically optimizes the hearing aid to maximize user
comfort and audibility in that environment without any user
interaction.
The Inspiria SA3286 comes with Evoke advanced
acoustic indicators. Evoke allows manufacturers to provide
more complex, multi−frequency tones, in addition to
traditional programmable tones for memory changes and
low battery indication, which can simulate musical notes or
chords.
The Inspiria SA3286 is equipped with a noise source that
can be used in treating tinnitus. The Tinnitus Treatment
noise can be shaped and attenuated and then summed into
the audio path either before or after the volume control.
The Narrow−band Noise Stimulus feature allows the user
to generate stimuli from the device that can be used for in situ
audiometry.
The Inspiria SA3286 delivers advanced features and
enhanced performance previously unavailable to a product
in its class. As well, the Inspiria SA3286 contains security
features to protect clients’ Intellectual Property against
device cloning and software piracy.
Signal Path
There are two main audio input signal paths. The first path
contains the front microphone and the second path contains
the rear microphone, telecoil or direct audio input as selected
by a programmable MUX. The front microphone input is
intended as the main microphone audio input for single
microphone applications.
In iSceneDetect, FrontWave, ADM or Automatic ADM
operation, a multi−microphone signal is used to produce a
directional hearing instrument response. The two audio
inputs are buffered, sampled and converted into digital form
using dual A/D converters. The digital outputs are converted
into a 32 kHz or 16 kHz, 20−bit digital audio signal. Further
IIR filter blocks process the front microphone and rear
microphone signals. One biquad filter is used to match the
rear microphone’s gain to that of the front microphone. After
that, other filtering is used to provide an adjustable group
delay to create the desired polar response pattern during the
calibration process. In iSceneDetect, ADM and Automatic
ADM, the two microphone inputs are combined in an
adaptive way while in FrontWave operation the combination
is static.
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