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CROS and Bi-CROS Hearing Aid & Solutions for Single Sided Hearing Loss

Fantastic Solutions for Single Sided Deafness

Bi-CROS and CROS Solutions

Single-sided deafness (SSD) causes real problems, even if the better ear has excellent hearing. Single-sided deafness can lead to increased stress and anxiety for people who suffer from it. Quite often, they will begin to avoid social interaction, due to difficulty in following conversations. CROS (Contralateral Routing Of Signal) systems were designed so that people with SSD could have access to sound from their bad side. The devices came into their own with the introduction of wireless audio streaming which meant they no longer needed to be physically connected. Wireless CROS systems are now prevalent, and I have had some fantastic success with Patients who use them. Let's talk about CROS and Bi-CROS. 

How A CROS System worksWhat is a CROS System?

A Contralateral Routing Of Signals (CROS) hearing aid is a type of hearing device that is used to treat unilateral hearing loss (single sided hearing loss). It takes sound from the ear with weaker or no hearing and transmits the sounds to the ear with better hearing. In point of fact, the CROS device usually is not a full hearing aid. Great thanks to Signia who produced the images that have been used here.

It has microphones and an amplifier chip but no speaker, instead it transmits the sound wirelessly to a receiving hearing aid on the better ear. It may seem strange to wear a hearing aid on your good ear. However, all it is doing is delivering the sound from your bad ear. It isn't amplifying any sound as such. 

This type of set-up allows you to have access to sound from both sides of your head which makes a tremendous amount of difference. God gave you two ears for a reason, and it wasn't just to make you pretty. 

Bi-CROS visual explaining how a Bi-CROS system worksWhat is a Bi-CROS System?

A BI-CROS hearing aid type is, in fact, similar to the CROS system, it is just a CROS transmitter paired with an active hearing aid. A Bi-CROS system is used when someone has an asymmetrical hearing loss, that is a hearing loss with one ear better than the other. In other words, a person who has a mild to moderate hearing loss in one ear, but a profound or total hearing loss in the other is an ideal candidate for a Bi-CROS system. 

Again, the CROS device works as a transmitter which captures the sound from the bad side and transmits it to the hearing aid on the better side. The hearing aid on the better side delivers the sound from the worst ear and amplifies the sounds from the better side. Not only does it do that well, it even does so in such a manner that you believe that you hear from your dead ear. 

These devices never fail to amaze me, I have used them with several Patients over the years, and I am still amazed at the outcomes. They deliver, allowing users to get on with their life. 


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Oticon Bi-CROS and CROS Solutions

Oticon has entered the CROS/BiCROS device space with a new transmitter that is based on their Velox S platform. The device which was announced in September 2019 is based on their miniRITE-T model and it uses their OpenSound Navigator and TwinLink technology to provide what they call 360-degree hearing even when streaming audio. Let's take a look at what it is, what it does and finally what you can use it with.

Oticon CROS

CROS & BiCROS Transmitter

The device itself is an intelligent transmitter of audio, like other CROS devices, it picks up the audio from the deaf or extremely bad ear and transmits it to the good or better ear. They have based the device on the miniRITE-T which means it is powered by a 312 battery and it has a volume control. The device can be used in both a CROS setup and a BiCROS setup. The volume control can be used to increase, or decrease, the volume of the streaming audio.

OpenSound Navigator

The device utilises the OpenSound Navigator (OSN) to process the signal before it is transmitted to the device on the better ear. They say:

"OpenSound Navigator is key to delivering a 360° listening experience to your patients. This technology constantly analyzes the environment, balances sound levels and removes unwanted noise. Oticon CROS features an optimized version of OpenSound Navigator that delivers a fuller, more immersive sound experience when listening to speech in noisy environments and at a distance for people with single-sided deafness."

To be honest, I am not sure if other CROS devices analyse and process the sound environment before transmitting the signal to the receiving ear. I have never thought to ask before. The use of the OSN in the case of the Oticon CROS is certainly an excellent idea, it will mean that the cleanest signal possible will be sent to the receiving ear, it should also mean that both the CROS and the hearing aid should work as a pair.

TwinLink dual-streaming

The Oticon CROSoffers TwinLink technology which makes it possible to connect to external audio sources via 2.4 GHz Bluetooth low energy, while simultaneously receiving sound transmission via Near-Field Magnetic Induction (NFMI) from the poorer to the better ear. That means that you can listen to streamed audio from your phone, or from a TV Streamer while the CROS transmits sound from your worse ear. It means that you could watch television or listen to music while carrying on a conversation with someone positioned on your poorer ear side. Most CROS systems do not offer this facility, with most of them, the CROS transmission has to be turned off to allow streaming of audio to the better ear.


The Oticon CROS can be used with any device from the Opn S 1, Opn S 2, Xceed, Xceed Play and Opn Play range. The device will not be able to be used with Opn S 3 devices because of the technical limitations in those devices.

Phonak Bi-CROS and CROS Solutions

Phonak's latest CROS and Bi-CROS solution is the new CROS B or Belong range. Phonak offers a full line-up of CROS models including custom in the ear CROS transmitters. The Belong range, in general, has been exceptionally well received by both users and professionals alike. Phonak took the opportunity to introduce their first ever, and the first ever, Lithium-ion rechargeable hearing aids with the Belong range. Initially, they added the Audeo B-R and then the Bolero B-R, with the introduction of the Belong CROS range, they introduced the first ever Lithium-ion rechargeable CROS transmitter. 

CROS B range from Phonak

All Hearing Aid Types and a Rechargeable 

As I said, Phonak offer three types of behind the ear and two custom in the ear hearing aid types in their CROS range. They are a 312 battery mini-in-canal device, a size 13 full shell device type, a size 13 BTE type, a size 312 BTE type and finally the rechargeable BTE type. Unfortunately, the rechargeable type is only available to you if you are buying an Audeo B-R 90, 70 or 50. The rechargeable devices are only available in the top three levels of technology at present. The rest of the CROS devices will pair with any type and level of the Belong technology. Let's take a look at them and the specs. 


The CROS B-R is powered by an integrated Lithium-ion battery which gives over twenty hours of use with one charge. That is more than most people will ever need. The device is similar in size and shape to the Audeo B-R, which you pair it with and it uses the same charging cradle. The device has a push button and uses a slim tube and an instant tip so that it is anchored in the ear. However, you can get a custom tip as well for more comfort. AS I said, the rechargeable device is only available to pair with the top three levels of technology. 


The CROS B-13 has both a push button and volume control; it can be paired with either a Belong RIC or BTE. It is powered by standard size 13 batteries and can be used with a slim tube and instant tip or a traditional ear hook which can be used with hearing aid tubing and an earmould. Again, if you go for the slim tube, you can get a custom tip for better comfort. 

CROS B-312

The CROS B-312 has a push button but no volume control, and it can be paired with either a Belong RIC or BTE. It is powered by normal size 13 batteries and can be used with a slim tube and instant tip or a traditional ear hook which can be used with hearing aid tubing and an earmould. Again, if you go for the slim tube, you can get a custom tip for better comfort. 

CROS B-312 Custom

The CROS B-312 custom has a push button and can come with optional volume control.  It can be paired with any Belong custom hearing aid. It is powered by regular size 312 batteries. 

CROS B-13 Custom

The CROS B-13 custom has a push button and can come with optional volume control.  It can be paired with any Belong custom hearing aid. It is powered by ordinary size 13 batteries. 

Binaural Voice Streaming

This feature is one of the reasons that Phonak hearing aids do so well in noise. The CROS B leverages a feature called Stereozoom, which allows the focus of the microphones on one voice in a crowd and they also offer the Speech in Loud Noise program with StereoZoom. It is available in combination B90 (as an automatic feature), and B70 (as a manual programme feature) performance level hearing aids. For the lower performance levels, CROS B provides Real Ear Sound for the 50 and omnidirectional microphone modes for the 30.

Multiple Programmes

That is another feature that is available on Phonak CROS systems which aren't available elsewhere. You have access to various programmes with a Phonak CROS system. This can be handy if there is a particular situation where you may be having trouble. It means that a singular programme can be fine-tuned for just that situation. 

Streaming Accessories

The CROS B devices are compatible with all of the streaming accessories that Phonak make available. Once a streaming device is detected, the CROS device shuts off, and the streamed audio is heard directly in the hearing aid on the better ear. Once the streaming audio is stopped, the CROS B automatically begins to stream audio from the worst side. That's a pretty smart feature; other manufacturers don't offer. 

Widex Bi-CROS and CROS Solutions

Widex CROS rangeWidex first introduced the Fashion CROS several years ago, it then followed up with the Fusion CROS device a little later. The Widex CROS has been very well received. Again, I have used the devices with Patients and me, and more importantly, the Patients have been pleased. Widex don't offer the range of types of CROS that Phonak does, but in fairness, no hearing aid brand provides the range of CROS devices that Phonak does. 

The latest CROS devices from Widex are from the Unique hearing aid range, however, at the time of writing this, Widex has just introduced a new hearing aid platform called the Evoke range. I believe that they will follow up this year with new Evoke based CROS devices. 

All levels of technology

The Widex CROS systems can be paired with any wireless hearing aid from all of their levels of technology. In general though and to keep it simple, generally they are paired with either Fashion or Fusion devices by most professionals. 

The Best Features Available

The feature set available on a Widex CROS is dependent on the level of hearing technology you pair the device with. The higher the level of tech, the better the feature set is. 

Just One Programme

Unfortunately, when you use a Widex CROS, it locks the other hearing aid to only one automatic programme. The automatic programmes from Widex are excellent. However, it does limit the fine-tuning possibilities for a specific situation. 

Streaming Accessories

The Widex CROS is not as intelligent as the Phonak CROS, to use any streaming device you need to turn the CROS transmitter off. Only then will you be able to use an external Widex streamer. 

In synopsis, while the Widex CROS system may look weaker than the Phonak system, in my experience it performs well, and people get on pretty well with it. 

Signia Bi-CROS and CROS Solutions

Signia introduced a CROS/BiCROS system a couple of years ago, with the introduction of the new NX platform, they now offer two CROS/BiCROS solutions for people with an unaidable hearing loss in one ear. They now offer the CROS Pure 312 and the CROS SIlk, both of which are compatible with their Nx hearing aid range. 

CROS Pure 312

Pure 312 and CROS Pure 312

Signia say the CROS Pure 312  offers a natural hearing experience for CROS wearers with the convenience of direct streaming. The CROS Pure 312 is an excellent solution for anyone with an unaidable hearing loss in one ear. Because the Nx range is direct streaming hearing aids, which means they are Made For iPhone. The CROS Pure 312 offers high quality sound and Bluetooth connectivity. The Nx range also delivers the most natural sounding own voice experience. 

The CROS Pure 312 is the first CROS accessory that supports direct streaming of music and phone calls to your hearing aid without the need for an intermediary device. It is also fully compatible with Signia’s myControl App for convenient remote control and more.

The new CROS Pure 312 Nx is compatible with the following hearing devices:

  • Pure 312 Nx
  • Pure 13 Nx
  • Pure Charge&Go Nx
  • Motion 13 Nx
  • Motion 13P Nx


Silk Nx with CROS Silk

The CROS Silk Nx is probably the most discreet CROS device for people with unaidable hearing loss in one ear. The Silk is an interesting device, it is a discreet instant fit in the ear hearing aid. Now, they have designed a Silk CROS solution. The new CROS Silk receives sound on that side and transmits it to a hearing aid on the other side.

You can enjoy a more natural hearing experience thanks to CROS Silk’s incredibly small design, its placement in the ear and exceptional sound quality.  Using the soft silicone Click Sleeves, CROS Silk can be fitted to many sizes of ear instantly. The CROS Silk can also be used with the touchControl App from Signia allowing you to adjust volume and the balance between the sound from your left and right with just a few taps on your smartphone.

The new CROS Silk Nx is compatible with the following hearing devices:

  • Silk Nx
  • Insio Nx

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