RHYTHM R3710

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13

Mode 3: Static Switch on MS1 and MS2

This mode uses two static switches to change memories.

Table 8 describes which memory is selected depending on

the state of the switches.

In this mode, it is possible to jump from any memory to

any other memory simply by changing the state of both

switches. If both switches are changed simultaneously, then

the transition is smooth. Otherwise, if one switch is changed

and then the other, the part transitions to an intermediate

memory before reaching the final memory. The part starts in

whatever memory the switches are selecting. If a memory is

invalid, the part defaults to memory A.

This mode is set by programming the ‘MSSMode’

parameter to ‘static’ and ‘Donly’ to ‘disabled’.

Table 8. MEMORY SELECTED BY STATIC SWITCH

ON MS1 AND MS2 MODE; (EXAMPLE WITH FOUR

VALID MEMORIES)

MS1

MS2

Memory

OPEN

OPEN

A

CLOSED

OPEN

B (if valid, otherwise A)

OPEN

CLOSED

C (if valid, otherwise A)

CLOSED

CLOSED

D (if valid, otherwise A)

Mode 4: Static Switch on MS1, Static Switch on MS2

(Jump to Last Memory)

This mode uses two static switches to change memories.

Unlike in the previous example, this mode will switch to the

last valid memory when the static switch on MS2 is

CLOSED. This means that this mode will only use a

maximum of three memories (even if four valid memories

are programmed). Table 9 describes which memory is

selected depending on the state of the switches.

This mode is set by programming the ‘MSSMode’

parameter to ‘static’ and ‘Donly’ to ‘enabled’.

Table 9. MEMORY SELECTED BY STATIC SWITCH

ON MS1, STATIC SWITCH ON MS2 (JUMP TO LAST

MEMORY) MODE

MS1

MS2

Memory

OPEN

OPEN

A

CLOSED

OPEN

B (if valid, otherwise A)

OPEN

CLOSED

D

CLOSED

CLOSED

D

In this mode, it is possible to jump from any memory to

any other memory simply by changing the state of both

switches. If both switches are changed simultaneously, then

the transition is smooth. Otherwise, if one switch is changed

and then the other, the part transitions to an intermediate

memory before reaching the final memory.

When MS2 is CLOSED, the state of the switch on MS1 is

ignored. This prevents memory select beeps from occurring

if switching MS1 when MS2 is CLOSED. The part starts in

whatever memory the switches are selecting. If a memory is

invalid, the part defaults to memory A. The part starts in

whatever memory the switches are selecting. If a memory is

invalid, the part defaults to memory A.

AGC−O and Peak Clipper

The output compression−limiting block (AGC−O) is an

output limiting circuit whose compression ratio is fixed at

∞ : 1. The threshold level is programmable. The AGC−O

module has programmable attack and release time

constants.

The AGC−O on R3710 has optional adaptive release

functionality. When this function is enabled, the release time

varies depending on the environment. In general terms, the

release time becomes faster in environments where the

average level is well below the threshold and only brief

intermittent transients exceed the threshold.

Conversely, in environments where the average level is

close to the AGC−O threshold, the release time applied to

portions of the signal exceeding the threshold is longer. The

result is an effective low distortion output limiter that clamps

down very quickly on momentary transients but reacts more

smoothly in loud environments to minimize compression

pumping artifacts. The programmed release time is the

longest release time applied, while the fastest release time is

16 times faster. For example, if a release time of 128 ms is

selected, the fastest release time applied by the AGC−O

block is 8 ms.

R3710 also includes the Peak Clipper block for added

flexibility.

Memory Switch Fader

To minimize potential loud transients when switching

between memories, R3710 uses a memory switch fader

block. When the memory is changed, the audio signal is

faded out, followed by the memory select acoustic indicators

(if enabled), and after switching to the next memory, the

audio signal is faded back in. The memory switch fader is

also used when turning the Tone Generator on or off, and

during SDA programming.

Power Management

R3710 has three user−selectable power management

schemes to ensure the hearing aid turns off gracefully at the

end of battery life. Shallow reset, Deep reset and Advanced

Reset mode. It also contains a programmable power on reset

delay function.

Power On Reset Delay

The programmable POR delay controls the amount of

time between power being connected to the hybrid and the