Digital Hearing Aids: Current “State-of-the-Art”
Digital hearing aids market for the first time in 1987 with the introduction of two manufacturers of hearing aids with digital signal processing (DSP) by the end of the 1980s. While the high technology of their time, these headphones had little success and soon was abandoned because of its large size and high battery drain.
Nearly a decade later, two manufacturers, once again, introduced digital hearing aids. At this time, technology has improved so that these headphones can be produced in a range of popular styles, from behind the ear (BTE) to the completely-in-the-canal (CIC). Despite its higher costs, which were well received by doctors and consumers. This initial success, combined with the promise of highly advanced signal processing, ensures that digital hearing aid technology has come of age.
So how far have we come? What is the current “state of the art” technology in digital hearing aids? Digital hearing aids are actually higher than their analog counterparts? To determine whether digital hearing aids are better for patients, it is important to focus on the processing and superior features of these instruments. Digital hearing aids can not be classified as a separate entity from analog hearing aids. “Digital” simply indicates that the analog waveform becomes a string of numbers for processing, and unfortunately, there is nothing inherently magical about this process. A linear-saturation output, digital hearing aid can easily be incorporated to provide sound quality and speech recognition than many analog hearing aids. Therefore, not only because it is superior digital is digital, DSP, but it allows manufacturers to create hearing aids with improved processing characteristics.
The digital advantage
Fortunately, both for dispensing audiologists and patients, there are features and advanced signal processing systems available in current digital hearing aids that have significant advantages over those in analog instruments. Digital potential benefits include those related to:
Gain processing. One of the major benefits associated with the gain flexible processing systems is the potential for increasing audibility of the sounds of interest without discomfort from the sounds of high intensity. While this is more general, a gain of compression rather than digital processing of itself, the large increase in the flexibility and control over the compression provided by DSP processing – such as input signal specific to the dependence of the band, a greater number of channels, and kneepoints less compression thresholds – can lead to improved audibility with less clinical effort. Expansion, unlike compression, has also been introduced in digital hearing aids. This treatment can lead to greater satisfaction of the listener by reducing the intensity of low-level environment and the sounds of the microphone noise that otherwise may have been annoying to the user.
Reducing digital votes (DFR). The most advanced systems to reduce feedback to control information, while the listener is using the headset. Moderate comments are then reduced or eliminated by using a system of cancellation or filtering notch. DFR can benefit users who experience occasional reactions, such as that associated with the movement of the jaw and proximity to objects.
Digital Noise Reduction (DNR). This treatment is designed to reduce the gain, either at low frequencies or bands, the steady-state signals (noise) are detected. Although the results of research supporting the effectiveness of DNR are mixed, they do indicate that the DNR can work to reduce the inconvenience and possibly improve speech recognition in the presence of non-fluctuating noise. DNR is sometimes advocated as an adjunct to treatment of directional microphones. While directional microphones can reduce levels of background noise, regardless of content temporary, limited to reduce noise from behind or on the sides of the user.
Improved digital voice (DSE). These systems serve to increase the relative intensity of some segments of speech. DSE current processing identifies and increases the intervention, either on a temporary basis or, more recently, the spectral content. DSE in the headset is still relatively new and their effectiveness is due largely unknown.
Directional microphones and DSP. The capacity for directional earphones improve the effectiveness of signal to noise whenever the listener is now well established. In some cases, however, the combination of DSP with directional microphones can act to further improve this benefit. In some headphones, DSP is used to calibrate the microphones, control over the shape of the directional pattern, and automatically switch between omni-directional modes, and through expansion, further reducing the noise generated circuits directional microphones.
Digital hearing aids such as signal generators. Since digital hearing aids have a DSP in his heart, that are able to generate – as well as a process – the sound. Current digital hearing aids use this ability to carry out growth and the volume threshold for testing in order to obtain specific information for an individual patient’s ears, in combination with a hearing aid. Sound levels also can be verified through the headset, once it is appropriate. This technology has the potential both to improve the precision of hearing aids and accessories potentially streamline the installation process by reducing the need for some external equipment.
Current digital hearing aids are certainly exciting future and the possibilities are endless. Before long, digital hearing aids will replace their analog counterparts altogether. However, we must bring this technology to patients in an informative and educational way. Like many other high-tech devices, high expectations often accompany digital hearing aids. Appropriate advice on patients’ expectations are still more – not less – important as the technology continues to advance.