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Digital or Analogue?
Hearing aids work with the help of two basic types of technology
Analogue hearing instruments can amplify the continuous sound wave by simply making it larger. There are two sub-categories of analogue hearing instruments: conventional and programmable. These hearing instruments differ in the amount and degree of adjustments the Hearing Aid Dispenser can perform on the hearing device.
With conventional analogue the Hearing Aid Dispenser can only make limited adjustments.Conventional analogue hearing instruments use physical components such as a microphone, an amplifier, a receiver, filters and resistors that are designed to alter the acoustic signal (such as speech) by changing the signal electronically. The signal is then transformed back into a sound wave which is delivered to the ear canal. Conventional hearing instruments have a fixed frequency response, thus amplifying incoming signals and background noise equally.
A programmable analogue hearing device allows the dispenser to adjust the amplifier more precisely to match your hearing loss. Programmable analogue hearing devices, when compared to their conventional equivalent, provide greater fitting flexibility. This means that the dispenser can easily change the way a programmable analogue hearing device operates through the use of an office computer. Sometimes the added flexibility of a programmable hearing instrument is an important feature.
Digital hearing instruments use a microprocessor (computer) chip as the central component. A microphone is also used but amplification, shaping and other signal modifications are achieved by representing the signal as a series of numbers. The numbers can be changed mathematically, more quickly and precisely than an electronic analogue signal, so the power of the hearing instrument is greatly enhanced.
Digital hearing instruments take the continuous sound wave and break it up into binary code. This is called digitising the signal and all digital hearing instruments do this.
Beyond just digitising the sound prior to amplification, there are differences in exactly how various digital hearing devices amplify or process sound. The more sophisticated digital hearing instruments are able to amplify the softest sounds of speech while at the same time subtracting out certain types of unwanted noises.
Digital signal processing allows hearing instrument designers to write computer programs, called algorithms that can be customised to each individual’s hearing loss. In addition, digital hearing instruments enable important features such as dual microphones and low battery warning signals to be placed into a small in-the-ear device.
It is this potential that makes digital hearing devices so promising for so many hearing losses. Selecting the type of hearing instrument that is right for your hearing loss and unique listening needs requires the guidance of a professional well-versed in all of variations of hearing instrument technology.
Digital hearing aids can be programmed to reduce background noise. For enhanced TV / music/ loop / additional programs can be ordered.
New digital hearing instruments can self-adjust for volume and frequency response (base, mid-range and treble), taking into account the individual’s hearing loss as well as difficult hearing environments. Digital hearing instruments self-adjust millions of times per second, which means the audio signal can be tailored with far greater flexibility, speed and precision.
Hearing Instrument Development
15 years ago, all hearing instruments fell into the 'conventional analogue' category. These hearing instruments provided minimal ability for the dispenser to adjust them based on problems the patient was experiencing.
In order to give the Hearing Aid Dispenser greater adjustment capabilities and to provide more advanced signal processing, programmable analogue instruments were developed 10 years ago. These instruments provided greater patient satisfaction. However, they still could not manipulate sound to provide the most advanced signal processing.
Digital hearing instruments were introduced to the market in 1996. Digital signal processing allows manufacturers to create and execute elaborate signal processing schemes which increase the patient's comfort and speech understanding.
