Digital Hearing Aid Design: The State-Of-The-Art Solution for Hearing Loss

During the last five years, there has been an explosion of digital hearing aids on the market. To date, there are twenty-two manufacturers for digital hearing aids. The digital hearing aid was first introduced before the end of the 1980s. Back then, hearing aids used digital signal processing or DSP, which became the basic framework for the recent digital hearing aid. The evolution of digital hearing aid design made it possible for digital hearing aids to be incorporated with the several types of hearing aids such as behind-the-ear (BTE) and completely-in-the-canal (CIC) styles.

The digital hearing aid design simply constitutes the conversion of analogue waveform into a string of numbers for processing. Additionally, digital hearing aid design in the term of using digital signal processing allows several manufacturers to proving hearing loss solutions with enhanced processing and features.

Compared with the traditional analog hearing aid, the amount of processing that can be done through the digital hearing aid design is impressive. The aids have a combination of several features such as: two to fourteen frequency bands bundled with crossover frequencies that could be adjusted, a single microphone, dual microphones allowing directional listening, reduction in the background noise, speech enhancement, reduction in feedback, protection from loud sounds, and the automatic gain control or AGC. Through the digital hearing aid design, the processing of sounds binaurally, filtering in the ear canal, reverberation lessening and supplying of direct digital input from a digital telephone and other devices were given the possibility.

The digital hearing aid design also suggests the possibility of customizing the hearing aid algorithms or features without changing the hearing aid itself.

The Elements of the Digital Hearing Aid Design

The digital hearing aid design consists of primary elements that are used for a DSP-based digital hearing aid. Typically, the design includes three semiconductor die that are stacked on top of each other. Additionally, the semiconductors contain modules such as: EEPROM or non-volatile memory, digital device and the analog device. Recently, the mentioned modules can be integrated into one or two semiconductor die. Also included in the digital hearing aid design is the battery usage of the hearing aid. The typical digital hearing aid would operate at 0.9V though there are some that implement the use of power management to monitor battery voltage. This method from other digital hearing aid designs alert the user whenever the battery is getting reasonably low and automatically shuts the aid down when the voltage is too low.
Analog hearing aids consume about 0.7 mA to 1.0 mA while digital aids consume 0.5 mA to 0.7 mA. Basing on the power consumption of the digital hearing aid, analog hearing aids also consume approximately equal amounts of power.