As the saying goes, “Necessity is the mother of all inventions”, the need to communicate better and to live a better life has acted as a driving force for technological advancements. With the advancement of technology, hearing aids are making great modifications which were just a dream in the past few decades. Previously the analog listening devices amplified every single sound which is often very annoying for the user. The advanced digital hearing aids can distinguish between speech and noise and provides a clear speech by reducing background noise. Today, these digital devices can provide a wide range of features that will improve your quality of life.
Although both the Analog and the Digital hearing aids have the same components - microphone, amplifier and receiver, the latter is packed with many advanced technological features. The first important step towards digitization of listening devices is the development of the technology of sound signals being converted to digital signals. It provides greater room for flexibility and thus, the digital hearing aids of this day comes bundled in greater number of features. In these devices, the sounds that it receives are separated into a sequence of sections. Each of the sections are then processed digitally and are then converted back into sound signals that can actually be ‘heard’ by the user. To better understand the technology used in modern day digital hearing aids, let us have a glance at its history.
The history of the digitization of sound goes back to World War II, when there was a need for developing a secure telephone link between Washington and London. The main aim of this project, known as the Project X, is to develop a method to digitize speech signals. It was done by securely encrypting the sound signals being transferred over the telephone lines, and this encryption was done by representing these signals as a sequence of binary digits, that is, 0s and 1s. Similar is the technology of today’s digital hearing aids.
To understand the use of modern technology in this generation’s digital hearing aids, let us have a look at a brief about channels and bands. The hearing aid channel, which is chiefly used in digital hearing aids, is characterized by filtering the sound by breaking the total speech frequency range into several smaller segments and then filtering each segment individually. The more the channels, the more is the flexibility to control the different sound frequency ranges by the device.
To understand channels better, let us discuss what bands used in different digital hearing aids are, and how are they different from these channels. Let us take a simple example of the overhead water tank. Water from the tank are being distributed to various lines or channels, which are then regulated by respective taps fitted at the end of each channel. These taps can be paralleled with bands in digital hearing aids, which control the flow of water (or sound frequency range). We adjust the taps according to our needs. Similarly, the channels are controlled or regulated by bands. In other words, the different sound frequencies received by digital hearing aids can be controlled by regulating the bands as per the type and degree of hearing loss of the user. Before channels turned out, the hearing devices used to amplify all the sounds the same, as seen in Analog ones.
The development of digital hearing aids followed the usual trial and error methods, and today it is still developing with new features coming to the forefront. It can be paralleled with the development of computer generations over the past few decades. In listening devices as well, Vacuum Tubes were used previously, and now nano chips or microprocessors are being used that not only save a great amount of space, but also makes room for a vast memory and storage. This is the reason why digital hearing aids have the capacity to store numerous programs and the user can switch between them according to his/her needs and surroundings. Also, these microprocessors can detect whether the sound is a speech or a noise and makes certain modifications accordingly to deliver a clear sound. Nowadays, digital hearing aids come with advanced features like feedback cancellation, noise reduction, precise amplification, bluetooth, FM and other wireless connectivities, and many more.
To conclude, digital hearing aids is a major technological breakthrough of the modern day. Although the first digital hearing aids were just modified versions of the Analog ones, the present day devices are so advanced that it can make the user completely forget about his/her hearing impairment.