Here's the full spec and products of the Oticon Dual taken from Oticon.com:

With Dual, great sound never looked better.

When you’re active and outgoing, you need a flexible hearing aid that offers the best sound quality in a wide variety of listening situations.

Conventional hearing aids force you to choose: Great looks or great performance. But why make that choice at all? With its high-tech elegance and the benefits of natural sound quality, Oticon Dual is designed to please inside and out.

You can get near natural hearing!

While standard devices work independently, a pair of Oticon Duals works together and present sounds in a balanced and natural way. We call this Spatial Sound.

Spatial Sound is to hearing devices what high-definition digital imaging is to TVs. Extra “audio pixels” provide so much detail that you can locate and identify sounds without having to think twice about it. Your reactions will be faster and more instinctive.

With Dual your life will no longer be ruled by your hearing loss. You will be in charge once more.

But don’t just listen to us – listen to Dual!

Dual Benefits

Dual captures a wider range of sounds than any other traditional devices on the market - particularly in the high frequencies. Speech will sound clearer and music far richer. You’ll also have a much better idea of where you are in relation to people and objects in your environment.

With Spatial Sound you can:

• enjoy dining out in busy restaurants
• communicate clearly and with confidence at meetings
• instinctively look the right way if a car is approaching from behind or someone starts to speak

Experience Spatial Sound

It’s not about being old - it’s about being smart
Oticon ConnectLine helps you make the most of today’s technologies. A smart optional device, called the Streamer ,picks up the sound from your mobile phone, landline phone, TV or mp3 player, and sends it straight into both ears.

There is a Dual just for you
From size and colour to performance, accessories and settings, a pair of Duals can be completely customized to fit your personal preferences and level of experience with hearing devices. Among the benefits are:

• a great design that’s almost invisible behind the ear
• lots of trendy colours to match your hair or skin tone

The RITE Style

Rather than putting the speaker in the hearing aid, Oticon Dual places it snugly in your ear. The “Receiver-in-the-Ear” concept makes Oticon Dual look virtually invisible - and sound exceptionally clear. The speaker is built into either a soft dome or micro-mould.

Where style choices are concerned, there are two types of Oticon Dual, four different styles – and a multitude of colours!

Making direct hearing aids comparisons are difficult because of the wide variety of styles and features sold on the market today.  Nevertheless, here are a few pointers of what to keep in mind when you compare hearing aids:

Sound Quality

Inferior sound quality causes health problems like severe headache and fatigue.  Moreover, while hearing aid technologies today are becoming quite sophisticated, hearing aids cannot exactly reproduce sounds as we actually hear them.  As such, it is important to check a device’s sound quality.  Is there too much background noise?  How about the sound when listening to music?  Do sounds sound natural?  This requires that you visit an audiologist to get adequate hearing aids comparison.  An audiologist can advise and help you adjust and fine-tune devices so as to determine how well various hearing aids work for you. 

Style and Size

While making hearing aids comparisons, it is important to determining which type – behind the ear, inside the ear, partially inside the ear canal or inside the ear canal – is most comfortable for you, both in terms of fit and wearability.  People’s preferences differ so it is important to try on each type yourself.  Moreover, if you are uncomfortable being seen wearing a hearing aid – as many people are – the latest device such as the Lyric, which fits deep inside the ear canal, may be best.  What is the point of spending thousands of dollars on a hearing aid that you will not wear? 

Form

There are two basic forms of hearing aids:  analog and digital.  Analog devices are the least expensive but mainly just make sounds louder.  Digital devices cost more.  They basically convert sound into computer bits and use chips to manipulate and make the sound more intelligible and natural for the user.  Almost all hearing aids today are digital, so go with digital unless cost is the determining factor in your comparison of hearing aids. 

Hearing Aids Cost

A very important factor in hearing aids comparison is affordability as digital hearing aids, which typically cost several thousand dollars, are not typically covered by insurance.  Decide if all the impressive features are needed.  Do you need multiple channels, water resistant hearing aids, voice reminders, and Bluetooth?  More features generally mean higher prices. 

Battery & Power

Hearing aid devices today are now almost all powered by batteries to ensure flexibility and mobility.  The batteries are typically zinc air batteries which activate when zinc mixes with air when a tab is peeled off the battery.  The batteries come in different sizes that are standardized, colour coded and widely available.  In comparing hearing aids, power consumption is an issue.  Some hearing aids require more power, which means that they require larger batteries and has a shorter life-span. 

Warranty & Contract

Different companies offer different contracts and terms of warranty regarding the time span covered and parts included in the terms. Knowing all this information is necessary for a proper hearing aids comparison.  Most state laws require a minimum trial period.  Make sure you use it before you buy so you can return the hearing aid if it does not work for you.

Additional Adjustments

Finally, there are hearing aid devices in which manual adjustments can be made to adjust almost each and every feature and others that are not very configurable.  It is important to take this into account when making proper hearing aids comparisons. 

Lastly, do not expect miracles and have overly high expectations.  Most people need time with hearing aids need to retrain their brains to hear.