Clarion Platinum Sound Processor Podręcznik Użytkownika Pobierz pdf (Strona 13)

Fitting guidelines

Introduction

Successful application of an FM system with cochlear implants

depends on several clinical-adjustable parameters. In the

receiver, the FM gain may influence speech recognition.

Within the speech processor, the input dynamic range (IDR),

microphone sensitivity and audio mixing ratio may affect

performance. Recent studies have evaluated the best settings

for optimal FM performance.

Using Dynamic FM (MLxi receiver and

Dynamic FM transmitter)

Since the Dynamic FM system adjusts the FM gain according

to the surrounding noise, one setting can be applied which is

beneficial in both calm and noisy situations. It is recommended

that the MLxi is pre-programmed for the specific processor

type in order to be sure FM levels are appropriate. Please refer

to the section “AutoConnect” on page 6 for more information.

On most speech processors no special steps have to be taken

to achieve maximum Dynamic FM benefit! The only exceptions

are speech processors from Cochlear Corp. For Cochlear

speech processors it is strongly recommended to activate the

auto sensitivity control (ASC) in the FM specific program.

Please see the overall recommended processor setting in the

table below:

With Dynamic FM, the need for adjusting processor parameters

in noise should be negligible. Even in very noisy situations,

there should be no need for a different mixing ratio since the

FM gain is up to 14 dB higher than in quiet. If, however, in

some special situations FM only is required, please follow the

guidelines below.

Using Classic FM

When using a Classic FM system, speech understanding in

noise may be poorer than with Dynamic FM since the

receiver does not automatically adjust the gain. Programming

a high gain value in the MicroMLxS is not the solution, as

it may be perceived as too loud and distorted in quiet

environments.

As a solution, a different audio mixing ratio for the FM

program may be selected or the microphone sensitivity may

need to be altered depending on the listening situation and

the processor type.

The next table shows what can be done to improve listening

in noise.

Brand Audio

mixing ratio

Additional remarks

Cochlear 1:1

Employ mapping from normal

listening program without FM.

Enable ASC for the FM program.

Cochlear Baha®

Divino, Intenso, Compact: Turn

AGCO as high as it is tolerable

for the patient. A maximum

AGCO is to be preferred.

Advanced

Bionics

50/50

Employ mapping from normal

listening program without FM.

MED-EL

Employ mapping from normal

listening program without FM.

Neurelec

Employ mapping from normal

listening program without FM.

Cochlear

Enabling ASC will already show significant better speech

understand in noise. If this is not enough,

an audio mixing ratio of 2:1 or 3:1 may be considered.

Advanced

Bionics

Program the FM gain of the receiver as high as it is

tolerable by the CI user. The +14 gain setting is recom-

mended (Schafer et al, 2008). If listening performance

in noise is still poor, an audio mixing ratio of 30/70 may

be considered.

MED-EL DUET1/ OPUS1/ TEMPO+: Reduce microphone sensitivity

Neurelec

May change the mixing ratio. For Digi SP and Digisonic

BTE, the sensitivity potentiometer remains accessible to

optimize hearing performance while using the FM system.

Note that when a 30/70 or 1:3 audio mixing ratio is employed,

input to the processor microphone is attenuated by 10 dB.

Therefore, when FM is not in use, the listener should return

to an equivalent (e. g. 1:1 or 50/50) audio mixing ratio to

avoid listening with an attenuated processor microphone.

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