SONIC CROS MNR T R User guide

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Sonic CROS MNR T R

CROS | BiCROS Fitting Guide

Contralateral Routing of the Signal (CROS) is an effective way

to manage single-sided deafness (SSD). Continue reading to

learn how to successfully ﬁt your patients who are candidates for

CROS or BiCROS ﬁttings with the Sonic CROS miniRITE T R and

EXPRESS

ﬁt

® Pro.

2Guide – Sonic CROS MNR T R and BiCROS MNR T R

Table of Contents

A word about single-sided deafness 2

What is CROS? 3

Candidacy CROS 3

What is BiCROS? 4

Candidacy BiCROS 4

Sonic CROS/BiCROS transmitter MNR T R 5

Fitting CROS/BiCROS in EXPRESS

ﬁt

Pro (from version 2021.2 onwards) 5

Considerations for counseling 11

General Q&A 12

Veriﬁcation with Real Ear Measurement (REM) 13

A word about single-sided deafness

Single-sided deafness (SSD) is deﬁned as “unaidable hearing in one ear and normal hearing or an aidable hearing loss in

the other ear” (Taylor 2010).

This describes a person who suffers from unilateral hearing loss which is so great that he or she does not beneﬁt from

ampliﬁcation in that ear.

It is important to understand that the term SSD covers not only people who are completely deaf in the impaired ear – it

also refers to people who have some hearing left, but their speech recognition is so poor that traditional ampliﬁcation

does not provide beneﬁt. In fact, people with that condition typically reject direct ampliﬁcation on the profoundly

impaired ear.

SSD can be present at birth or acquired later due to external factors such as outer, middle, or inner ear abnormality,

infections & syndromes (meningitis, tumor, Meniere’s disease, mumps), head injuries and exposure to loud noise.

3Guide – Sonic CROS MNR T R and BiCROS MNR T R

Condition: better ear projects normal

hearing thresholds

Better ear Poorer ear CROS transmitter Unilateral ﬁtting

Receiver placement

Aidable hearing loss ✖ ✔

Profound hearing loss ✔ ✖

✖ ✔

Distorted hearing ✔ ✖

Deafness ✔ ✖

Candidacy CROS

Better ear

normal hearing

Poorer ear

unaidable

What is CROS?

The abbreviation stands for: Contralateral Routing of Signal

CROS describes a device designed to overcome the obstacles of single-sided deafness (SSD). This includes obstacles

such as overcoming the head shadow effect or the inability to locate the direction of sound sources.

Equipping SSD patients with a CROS will help them manage these obstacles and allow them to become a two-sided

rather than a one-sided listener.

A transmitter, typically with two microphones, is placed on the poorer ear which picks up sounds and sends them

wirelessly to the better ear where the receiver is placed. These sounds are then perceived and processed by a

healthy cochlea.

4Guide – Sonic CROS MNR T R and BiCROS MNR T R

What is BiCROS?

The abbreviation stands for: Bilateral Contralateral Routing of Signal

A BiCROS system functions similarly to the CROS system but is relevant for people that also need ampliﬁcation on the better

hearing ear. This means that the better ear also has a certain degree of hearing loss.

In addition to receiving sounds from the transmitter placed on the poorer ear, the receiving device also provides

ampliﬁcation based on the hearing loss in the better ear. The signals from the two ears are mixed and directed into the ear

canal of the better ear for further processing by the better cochlea.

Condition: better ear projects

aidable degree of hearing loss

Better ear Poorer ear BiCROS transmitter Bilateral ﬁtting

Hearing aid

Aidable hearing loss ✖ ✔

Profound hearing loss ✔ ✖

✖ ✔

Distorted hearing ✔ ✖

Deafness ✔ ✖

Candidacy BiCROS

Better ear

aidable hearing

Poorer ear

unaidable

5Guide – Sonic CROS MNR T R and BiCROS MNR T R

Sonic CROS/BiCROS transmitter

MNR T R

• Wireless device

• Connects to all Sonic Radiant miniRITE and miniBTE styles launched from 2020.2 onwards

Fitting CROS/BiCROS in EXPRESS

ﬁt

Pro (from version 2021.2 onwards)

The CROS transmitter does NOT establish any connection to the EXPRESS

ﬁt

Pro ﬁtting software. All effective

programming is applied to the receiver/hearing instrument on the good or better ear. The moment a CROS transmitter is

selected, the hearing instrument will recognize and connect with the CROS transmitter via NFMI. The hearing instrument

and CROS transmitter must be within a proximity range of 20-30 cm / 7-12 in to be able to ﬁnd each other and connect.

1. Hearing instrument

a. Select the CROS transmitter for the poorer ear and the receiver/hearing instrument for the opposite normal

hearing ear (figures 1a and 1b)

b. Detect the receiver/hearing instrument

Figure 1a: Better ear: normal hearing (L)

6Guide – Sonic CROS MNR T R and BiCROS MNR T R

Figure 1b: Better ear: aidable hearing (L)

Figure 2a: CROS mode is selected

2. Fitting

a. Figure 2a: Open the CROS/BiCROS

tab at the top of the Fit Instrument

screen to select the mode: BiCROS,

CROS, or No CROS/BiCROS. The

mode needs to be chosen for every

additional program.

→ CROS transmitter is not avail-

able in programs with telecoil

b. The receiver (hearing instrument)

microphone is off by default

Move one ﬁnger backwards and forwards across the

microphone ports of the CROS transmitter to get a reaction

from the patient. If the scratchy sound is audible, that means

that the CROS transmitter is working and connected with

the receiver.

Tip

7Guide – Sonic CROS MNR T R and BiCROS MNR T R

Figure 2b: BiCROS mode is selected

a. Figure 2b: When BiCROS mode is selected, the hearing instrument microphone is on by default

b. Adjust desired input level for the CROS transmitter

c. The CROS transmitter input level is individually adjustable in each listening program

Adjust the transmitter input level with the aim of balancing the sounds coming from the CROS transmitter

and the sounds coming from the hearing instrument.

The CROS transmitter input level is adjusted in 2 dB steps. The default for the balance of the transmitter

input level is set to 0. This means that there is equal sound from the transmitter and receiver (hearing

instrument) entering the ear canal.

Validate if the perception of sound is equal by playing sounds with the same intensity from both sides of

the patient’s head (ﬁgure 3a) or if only one speaker is available from behind the patient (ﬁgure 3b). If the

sound is perceived more on the better ear, increase the CROS transmitter input level. If the sound is

perceived more on the poorer ear (side with the CROS transmitter), reduce the input level. It can be

challenging to ﬁnd a perfect match but try to get as close as possible for balanced detection of sounds.

The receiver input level is ﬁxed but can be adjusted in the overall gain in Fine Tuning.

Tip

8Guide – Sonic CROS MNR T R and BiCROS MNR T R

Figure 4a: CROS mode is selected

3. Program Speciﬁc Features

a. Figure 4a: Radian Noise Reduction is set to –6 dB (medium) by default and cannot be changed

b. Adjust desired attenuation for Impulse Noise Reduction. The correction of the sound is regulated by the

adjustments in the receiver (hearing instrument) and the flexibility of the adjustment steps depends on the

technology level.

c. The setting can be changed for individual programs (except pre-set programs that do not offer this flexibility)

3a: Validation 3b: Validation

9Guide – Sonic CROS MNR T R and BiCROS MNR T R

Figure 4b: BiCROS mode is selected

a. Figure 4b: Radian Noise Reduction in the CROS transmitter is set to –6 dB (medium) by default and cannot be

changed

b. The features in the receiver (hearing instrument) can be adjusted. The flexibility depends on the

performance level.

c. The settings can be changed for individual programs (except pre-set programs that do not offer this flexibility)

4. End session

a. The frequency for audible indicators in the CROS transmitter cannot be configured, they are fixed at

1500 Hz, whereas the frequency for indicators in the receiver (hearing instrument) are on 1000 Hz by default and

can be changed as normal. This helps to distinguish which beep alert is coming from the CROS transmitter and

which from the receiver/hearing instrument.

b. Be aware that the beeps are configured to be High Frequency for transmitter alerts, whereas receiving hearing

instrument alerts are Medium Frequency by default. If no changes to beeps are made by the hearing care profes-

sional, beeps will sound different between the transmitter and the receiver to help the patient distinguish between

the two more easily.

c. Battery level of the CROS transmitter is not displayed in EXPRESS

fit

Pro (figure 5).

d. VC steps are not adjustable for the CROS receiver (hearing instrument). This is only possible when BiCROS

is selected.

10Guide – Sonic CROS MNR T R and BiCROS MNR T R

Figure 5: Batteries

Battery health cannot be read out for the CROS MNR T R transmitter.

General settings of the CROS MNR T R transmitter that

are ﬁxed:

a. -6 dB Radian Noise Reduction setting is

always on

b. The Radian Directionality setting defaults

to Medium for challenging acoustic

environments, and is set to a True Omni Plus

setting

c. Radian Engage is fixed at a Medium setting

(when in directional setting)

d. VC range -20 to +10 dB

e. VC step size 2.5 dB

f. Radian Speech Processing: Speech Optimizer -

Medium; Noise Minimizer - Off

g. 10 kHz bandwidth

h. Wind Noise Reduction is on

i. Extended Dynamic Range is enabled

j. Transmission delay from the CROS transmitter

to the receiver / hearing instrument is 14 ms

k. VC steps are not adjustable for the CROS

receiver (hearing instrument). This is only

possible when BiCROS is selected.

EXPRESSﬁt Pro features that are excluded from the

CROS/BiCROS MNR T R transmitter:

a. Measurement of Adaptive Feedback

Canceller Pro

b. In-situ audiometry testing

c. Test box measurement mode

d. CROS transmitter is not available in programs

using telecoil. This is only possible when BiCROS

is selected.

11Guide – Sonic CROS MNR T R and BiCROS MNR T R

Considerations for counseling

A person’s ability to cope with SSD is highly variable:

• Patients with acquired SSD report a greater impact on their quality of life as they struggle to accept the change in

their life.

• Patients with congenital SSD have developed excellent coping mechanisms (placement, lip reading, etc.). The

coping mechanisms depend on the quality of hearing of the better ear.

Using CROS/BiCROS in a complex listening situation may contribute to worse speech understanding. Instead, counsel

the patient that they may still need to adapt by using coping strategies (e.g., turning head, adjusting the volume or the

sound balance of the transmitter) that might be of beneﬁt.

Some strategies:

• The patient must wear two devices, possibly with the better ear partially occluded and this might seem strange

• The patient’s ability to cope with their single-sided deafness likely depends on whether it happens suddenly or is

present from birth

→ Influence expectations and perceived benefit with a CROS system

• Avoid making guarantees such as:

→ Better sound localization

→ Restores binaural hearing

→ Improves speech understanding in complex listening situations

• Just as in a binaural fitting with hearing aids, the patient still needs to use listening strategies to get the best out

of each listening situation

• Works optimally in quieter listening situations

→ Use a quiet environment to test the patient’s ability to localize sound sources

• Then take the patient to a noisy place to demonstrate some examples of what to expect in a more challenging

situation. The additional input DOES NOT REPLACE normal hearing or traditional amplification.

• Noise may also be transmitted from the poorer to the better ear

→ Explain that distinguishing sounds in noisy areas is a learning process that might take several weeks

12Guide – Sonic CROS MNR T R and BiCROS MNR T R

QUESTION ANSWER

Is there any contraindication to ﬁt

CROS/BiCROS devices?

Yes, the CROS transmitter is not suitable for infants and

children below 5 years of age. For children 5-8 years of

age, special instructions are in the WARNING section of

the User Guide.

Is there Bluetooth functionality in the

CROS transmitter? No, there is none.

Is the CROS transmitter detectable by the

ﬁtting software? No

Is it possible to read out the battery health of the Li-ion

battery in the CROS transmitter?

No, the CROS transmitter does not connect to the

ﬁtting software.

Is the CROS transmitter visible in the ﬁtting software?

Yes (only after you have told the software that the

transmitter is there by selecting a CROS transmitter).

However, there is no image displayed.

Is the CROS transmitter visible in the SoundLink 2 app? No

Is it possible to read out the battery charge of the Li-ion

battery in the CROS transmitter in the

SoundLink 2 app?

No, the CROS transmitter is not shown at all in the app.

How does the CROS transmitter and receiver/hearing

instrument connect with each other?

They connect automatically if the CROS transmitter is

selected in EXPRESS

ﬁt

Pro. The technology used to

connect both is through NFMI (near-ﬁeld magnetic

induction). The CROS transmitter and receiver/hearing

instrument need to be as close as 20 – 30 cm / 7 – 12 in to

connect (which is roughly the width of an adult head).

When ﬁtting BiCROS in EXPRESS

ﬁt

Pro, can the

patient detect adjustments of balance between the

CROS transmitter and receiver/hearing instrument

signal in real time, so that adjustments can be made

while the receiver/hearing instrument is connected?

Yes

What happens if the CROS transmitter and receiver/

hearing instrument are further apart?

They will lose connection and will connect back when

within the correct distance.

How do I know that the CROS transmitter is paired with

the receiver?

“Scratch” on the CROS transmitter and listen on the

receiver/hearing instrument for audible sound

transmission from the transmitter to the receiver during

the ﬁtting of the receiver/hearing instrument.

Is there a start-up jingle in the CROS transmitter? No, any start-up jingle is in the receiver/hearing

instrument and not the CROS transmitter.

General Q&A

13Guide – Sonic CROS MNR T R and BiCROS MNR T R

Veriﬁcation with Real Ear

Measurement (REM)

CROS and BiCROS ﬁtting (information extracted from Interacoustics quick guides)

www.interacoustics.com/guides/test/hearing-aid-ﬁtting-tests/cros-and-bicros-ﬁtting from 2017

This Quick Guide is intended to give a brief explanation on how to ﬁt CROS and BiCROS type hearing instruments. The

instructions in this guide have been adapted from the methods stated by Hayes (2006) and Pumford (2005). Links to these

articles are provided at the bottom of this document.

The following points of instruction apply to the whole of this document and will aid understanding as to what is being

measured in the different conditions:

• The probe microphone is always placed in the aidable or normal hearing ear, never in the unaidable ear.

• The patient will change positions so that the loudspeaker is within the range of -90 ° through 0 ° to +90 °

relative to the front of the patient at different stages in the procedure. Images have been used below to aid your

understanding of this.

• The reference microphone is always located on the same side of the head as the loudspeaker.

14Guide – Sonic CROS MNR T R and BiCROS MNR T R

CROS Hearing instrument

Measurement one:

Measure the REUR/REUG of the best ear with the patient

at 45 ° or 90 ° to the speaker.

Note:

The CROS system is not added to the ear at this point.

Measurement two: Move the patient so that the loudspeaker

and reference microphone are to the side of the unaidable ear

(-45 ° or -90 ° relative to the poorer ear). Add the CROS system

to your patients’ ear and turn it on. You must also enable the

CROS setting in your Afﬁnity/Equinox or Callisto Suite.

Note: You do not need to swap ear side to perform this

measurement, all measurements are performed to the same

ear side from the ﬁrst measurement.

Run the ‘CROS Response’ measurement.

Run the ‘Better Ear REUG/REUG’ Measurement.

This measurement should lead to a similar curve. This measurement should lead to a similar curve.

Now you need to adjust your CROS system until the REAR/

REIG from the second measurement overlaps the REUR/REUG

from the ﬁrst measurement. Imagine the ﬁrst measurement to

be your target in this scenario.

Note: Make sure that if you run your ﬁrst condition at 45 °

then the second condition should be at -45 °. This is also

required for measurements run at 90 °. If this isn’t done,

then the measurement curves are not comparable.

Note: Probe microphone measurements cannot be applied to

transcranial/bone anchored CROS ﬁttings.

1. CROS Hearing instruments

The objective of this measurement is to make signals from the unaidable side of the head sound the same as signals from the

side of the better or normal hearing ear.

Dedicated protocols have been created for optimum application of this test. Contact the local Interacoustics distributor to get

them imported. This might be different depending on the equipment (brand, model) in use.

15Guide – Sonic CROS MNR T R and BiCROS MNR T R

BiCROS Hearing instruments

Measurement One: Measure the REUR/REUG of the best

ear with the patient at 45 ° or 90 ° to the speaker.

Remember to ensure the hearing instrument is inserted

and enabled in this scenario.

Measurement Two: Move the patient so that the loudspeaker

and reference microphone are to the side of the unaidable ear

(-45 ° or -90 ° relative to the poorer ear). Enable the CROS

system and the CROS setting in your Afﬁnity/Equinox or

Callisto Suite.

Note: You do not need to swap ear side to perform this

measurement, all measurements are performed to the same

ear side from the ﬁrst measurement.

Run the ‘CROS Response’ Measurement.

Run the ‘Better Ear REUR/REUG’ Measurement.

This should lead to a curve like below.

This measurement should lead to a curve like the below.

Now you need to adjust your CROS system until the REAR/

REIG from the second measurement overlaps the REUR/

REUG from the ﬁrst measurement. Imagine the ﬁrst

measurement to be your target in this scenario.

Note: Make sure that if you run your ﬁrst condition at 45 °

then the second condition should also be at 45 °. This is

also required for measurements run at 90°. If this isn’t

done, then the measurement curves are not comparable.

Note: Probe microphone measurements cannot be applied to

transcranial/bone anchored CROS ﬁttings.

2. BiCROS Hearing instruments

The objective of this test is like what has been shown above, however there is a hearing instrument on the better ear which

we need to consider.

The same dedicated protocol as used in the CROS instructions above is used for optimum application of this test. Please

contact your local distributor to get, and import these for use. This might be different depending on the equipment (brand,

model) in use.

Ensure you have already ﬁtted the hearing instrument without the CROS features enabled to a suitable algorithm based on

the patient’s scenario (i.e., NAL-NL1, NAL-NL2 or DSL).

Calibrate and insert the probe microphone into the aidable / better hearing ear.

16Guide – Sonic CROS MNR T R and BiCROS MNR T R

SONIC CROS MNR T R User guide

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