RHYTHM R3110
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11
Noise Generator for Tinnitus Treatment
R3110 offers a dedicated pin to control the Tinnitus
Treatment noise generation algorithm: TN−EN. This pin has
an internal pull−down resistor to ground (GND), which
disables the algorithm by default. When activated (pulled to
VB), Tinnitus Treatment is generated deploying
amplitude−scaled white noise, depending on adjustments
made via pin WB/NL. When the TN−EN pin is set high
(connected to VB) to enable the tinnitus algorithm, the
WB/NL pin controls the generated noise level (NL) as per
Table 4. The noise is injected into the audio path, as shown
in the block diagram of Figure 1 and the entire audio signal
is shaped using the internal filters controlled by the LC and
HC pins. The VC pin and, consequently the amount of
attenuation that it selects, only affects the audio signal and
not the tinnitus noise level. The tinnitus mode can be used
in conjunction with all three modes (Simples, Advanced and
Telecoil). In this configuration, it will control the tinnitus
noise level instead.
Using the R3110 Solely as a Tinnitus Masker Device:
R3110 can also be used as a tinnitus only device with no
microphones at all, only one receiver. In this configuration
all inputs will be connected to MGND (MIC and TC−IN).
Push Button Support
R3110 supports the use of momentary switches via the
Mode Select (MS) pin (#9). It allows rotating between the
three input modes (Simple, Advanced and Telecoil) as
defined earlier, this in a sequential manner. A momentary
switch needs to connect the MS pin (#9) to the VB pin (#8)
to enable this functionality. R3110 will switch from Simple
to Advanced Mode, then Telecoil, and then back to Simple,
each time the momentary switch is pushed. When this
function is not desired in the end product, the hearing aid, the
MS pin can be left floating.
Acoustic Indicators
In the configurations outlined both in the Telecoil Support
and in the Push Button Support sections, whenever R3110
transitions between modes, the audio path is temporarily
faded−out and an acoustic indicated is played. R3110 has
preconfigured acoustic indicators to notify the user of the
following events:
• Device startup
♦ Four sequential tones with the following audio
frequencies: A4 (440 Hz), F4 (349 Hz), G4
(392 Hz), C4 (262 Hz)
• MS pin: mode switches with momentary push button
♦ Simple mode: one tone at the C5 audio frequency
(523 Hz)
♦ Advanced mode: two sequential tones with
increasing audio frequencies G4 (392 Hz) and C5
(523 Hz), 250 ms duration and 50 ms silence
between the tones.
♦ Telecoil mode: three faded tones with increasing
audio frequencies E4 (330 Hz), G4 (392 Hz) and C5
(523 Hz).
• TC−EN pin : telecoil mode enabled
♦ Four sequential tones with increasing audio
frequencies C4 (262 Hz), E4 (330 Hz), G4 (392 Hz)
and C5 (523 Hz).
• Low battery
♦ Three sequential tones with decreasing audio
frequencies G4 (392 Hz), E4 (330 Hz) and C4
(262 Hz).
All tones exhibit a nominal 32 ms fade−in and fade−out
transition time. The duration of all the tones is 250 ms, and
the silence duration between tones is 50 ms. The level of the
tones is input referred and determined dynamically by
R3110 based on the input signal level as well as the volume
control.
Power Management and Low Battery Warning
As the voltage on the hearing aid battery decreases under
1.1 V, an audible warning signal is given to the user
indicating that the battery life is low. This indicator is
repeated every five minutes until the battery voltage is
further decreased under 0.88 V, at which point the device
shuts down. In addition to this audible warning and before
shut down, the hearing aid applies a sophisticated power
management scheme to ensure proper operation given the
weak battery supply and to maximize the device’s usable
battery life by reducing the gain to stabilize the supply based
on the instantaneous and average supply voltage levels.
Evaluation Environment and Hybrid Jig
The performances of R3110 can be evaluated by using the
hybrid jig evaluation board. As can be seen on Figure 1, a
number of evaluation features have been designed on the
hybrid jig, such as input and output audio connectors, output
amplification circuitry, microphone headers, push buttons,
toggle switches, analog potentiometers, a USB connection
as well as a wealth of other useful features that will allow
easy evaluation of the R3110 hybrid.
Figure 7. Hybrid Jig