Digital Hearing Aid Technology has considerably shrunk the size of Hearing Aids and they are equipped with lot of user-friendly functions. This post gives all details about the types of Digital Hearing Aids, Components of Hearing Aid, it’s working principle, advantages and disadvantages.
What is Digital Hearing Aid
An electronic device that the user wears in or behind his/her ear is referred as Hearing Aid. It aids the user to hear sounds louder with clarity which makes communication effective.
Fig. 1 – Introduction to Digital Hearing Aid
Digital Hearing Aid digitizes the sound, unlike the analog hearing aid which only amplifies the sound received. It is a device which cuts the received sound waves into small parts before amplifying it. This will improve the quality of the sound.
Fig. 2 – Image of Hearing Aid
Types of Digital Hearing Aids
The goal is to find a Hearing Aid that is both comfortable and enhances the ability to hear and communicate. They vary in size, features, price and style. They come in 3 different styles.
- Behind-the-Ear (BTE) Hearing Aid
- In-the-Ear (ITE) Hearing Aid
- Canal Hearing Aid
Behind-the-Ear (BTE) Hearing Aid
These Hearing Aids come with a plastic case worn behind the ear and are connected to a plastic earmold that goes inside the ear. These are recommended for people with mild hearing loss.
These Hearing Aids fit entirely inside the outer ear. The case holding is made out of hard plastic. These are recommended for people with mild to severe hearing loss.
These Hearing Aids come in two styles.
- In-the-Canal (ITC)
- Completely-in-Canal (CIC)
This type of Hearing Aid is made to fit the shape of one’s ear Canal. This is the smallest of all styles and hidden in the ear Canal. These are recommended for adults with mild to moderately severe hearing loss and not for young children.
Completely-in-Canal (CIC) Hearing Aid
This type of Canal aids are difficult for people to remove and adjust as they are very small in size. As they are small, there is less space available for batteries and hence the limited power and volume.
Components of Digital Hearing Aid
It mainly consists the following parts:
- Mini-Chip or Digital Signal Processor
Fig. 3 – Components of Digital Hearing Aid
It is the power source of the device. The batteries may be disposable or rechargeable.
It is responsible for capturing sounds from the environment and transmits to the Amplifier. There are two types of Microphones used in Hearing Aids. They are:
- Directional Microphones
- Omnidirectional Microphones
These types of Microphones pick up sounds which are in front of the User i.e. only in a single direction.
These types of Microphones pick up sounds from all the directions.
It accepts signals from Microphone and amplifies or increases the magnitude of the signal. The degree of amplification depends upon the device and the user using it. It is directly proportional to hearing loss. More the hearing loss, greater amplification is required and vice versa.
Receiver is nothing but Transducer that accepts signals from amplifier and converts it back to sound signal.
Mini-Chip or Digital Signal Processor
It accounts for processing of signals according to the user specifications.
How does Digital Hearing Aid Work
To understand the working principle, let us consider Fig. 4 below. Sound Waves from the environment are captured by the Microphones which are present on the device. The sound waves get converted in to numerical codes (Binary Codes) before they are transmitted to the Amplifier. The Amplifier accepts the signals transmitted from Microphones and increases the amplitude of the signal based on the information present in the codes. The Microchip or the Digital Signal Processor (DSP) processes the signal in accordance with the User’s needs. This Digital Signal is converted back to Sound signal by the Receiver or Transducer. This Sound Signal reaches the inner ear of the User.
Fig. 4 – Different Stages of Conversion of Signals
They can be programmed as per a person’s hearing loss. If a person has a hearing loss in both the ears, then, he will need two hearing aids to be delivered more natural sound to the brain. It can be customized based on Audio test performed before prescribing the Hearing Aid. The test results indicate the degree of hear loss and help the Audiologist program and design the aid according to the user’s needs.
Advantages of Digital Hearing Aid
The Advantages include:
- They have the capability of amplifying the sounds of certain areas that we need and not amplify the other areas that we don’t.
- There are unlimited ways in which the digital signal can be manipulated.
- Noise reduction technology is implemented in all hearing aids. They vary in the amount of noise reduction.
- They can be wirelessly interfaced with all Bluetooth devices, such as music players, TV, cell phones etc.
- Some hearing aids come with rechargeable batteries. Maintenance is easier as it eliminates the need for changing the battery.
- Improved pick up of sound coming from the front with the reduction of sound coming from behind.
- Designed and focused for sounds coming from a single direction and Multi direction.
- For a person with two Hearing Aids, aids are made to function together so that changes made on one ear are automatically reflected on the other.
- It can store pre-programmed settings for different environments and needs.
- Some Hearing Aids come with the remote control so that features can be adjusted without the touch of the device.
- Direct audio input allows one to plug into audio from a music device, television or a computer with a cord.
Disadvantages of Digital Hearing Aid
The disadvantages include:
- They don’t restore normal hearing. It can only amplify and make the sound more audible.
- It takes an individual some amount of time to get adjusted to an external device inside the ear.
- There could be feedback problems because of the short distance between the Microphone and the Receiver.
- Since the Hearing Aids are worn inside the ear, they are more susceptible to ear wax and can cause damage. Cleaning them every day is a must.
- The CIC aids are difficult to manage for some people as they are very small.
- Because of the placement of devices, they are more prone to repair.
- The more significant problem with the Canal style Hearing Aid fit is the feel of blockage or talking in a bucket.
- BTE Hearing Aids come with earbuds or ear molds. To preserve the acoustic, earbuds must be remade every two to four years.