Hearing Loss Treatment

It would seem that hearing is a second-rate sense when compared to vision in our visually oriented modern society. People with hearing loss delay hearing loss treatment because they are unaware of the fact that receiving early treatment for hearing loss has the potential to literally transform their lives.

Hearing Aids

Research by the National Council on the Aging on more than 2,000 people with hearing loss as well as their significant others demonstrated that hearing aids clearly are associated with impressive improvements in the social, emotional, psychological, and physical well-being of people with hearing loss in all hearing loss categories from mild to severe. Specifically, hearing aid usage is positively related to the following quality of life issues. Hearing loss treatment was shown to improve:

• Earning power
• Communication in relationships
• Intimacy and warmth in family relationships Ease in communication
• Emotional stability
• Sense of control over life events
• Perception of mental functioning
• Physical health

How Hearing Aids Work

While the processing of modern hearing aids is complex, and computer programming is required to make some of the adjustments, the basic components that make them work has not changed. The basic function of a hearing aid is as follows:

• Sound waves enter through the microphone, which converts acoustic signals into electrical signals.
• The amplifier increases the strength of the electrical signal.
• From the amplifier, the signal is then transformed back to an acoustic signal by the receiver (a miniature loud speaker).
• From the receiver the signal is channeled intro the ear canal, either through a small tube or through an ear mold.
• A battery is required to power the hearing aid and enable the amplification process.

Many hearing aids also have user controls (e.g. toggle switch, volume control wheel, push button, or remote control) that enable the wearer to adjust a variety of hearing aid parameters, including:

• Turning the hearing aid "on" or "off"
• Changing the volume
• Switching to the telecoil
• Switching between omni- and directional-microphone settings
• Switching to a different pre-programmed memory

Brief Guide to Modern Hearing Aid Technology

In addition to the basic features of hearing aids discussed earlier, there are many other features available in modern hearing aids-some of them are for convenience and ease of use, others are designed to improve speech understanding or listening comfort.

Adaptive Feedback Cancellation:

Acoustic feedback (whistling from the hearing aid) can be annoying, embarrassing, and in some cases, prevent the hearing aid wearer from using the correct amount of gain. Many of today's hearing aids have an automatic feature that quickly detects acoustic feedback and cancels it. This feature is designed to manage transitory feedback (e.g., caused by placing one's hand or a telephone next to the ear), and is not a solution to a poorly fitted ear mold or hearing aid. Although feedback can be managed it can never be eliminated completely no matter the hearing aid.

Automatic Gain Control:

AGC or compression is used to put a "ceiling" on loud sounds. Compression allows for soft, medium, and loud sounds to be programmed individually without any sound being too loud. The AGC also allows for most individuals to not worry about adjusting the volume on the hearing aid as the hearing aid will automatically adjust volumes in different environments, similar to a normal hearing ear.

Digital Noise Reduction:

With digital hearing aids, it is possible for the hearing aid to analyze an incoming signal and differentiate speech from a noise signal. If the dominant signal is noise , there is a reduction in gain while still helping to preserve audibility of speech. Note, however, that what a typical hearing aid user might consider to be "noise," (background talkers at a party) might not be considered "noise" by the hearing aid.

Digital Signal Processing:

Until recently, the majority of hearing aids utilized analog signal processing. This has changed rapidly the past few years, and today, nearly all hearing aids sold in the U.S. utilize digital signal processing. The advantage of digital processing is that less space is required, allowing manufacturers to include many more "programmable features" in a small package. Through the use of digital signal processing, the hearing aid can conduct an analysis of an incoming signal, and make a reasonable classification of the content-speech versus broad-band noise versus acoustic feedback (whistling) versus music, for example. This classification can then be used to trigger automatic activation of other special features.

Directional Microphone Technology:

Using special microphones or phase cancellation signal processing, it is possible to configure a hearing aid so that sounds from the side, and especially the back of the hearing aid user are amplified less than sounds originating from the front. It can serve as a type of noise reduction if the user is correctly positioned. Directional technology is available on all hearing aid styles except CICs (because of size constraints). Importantly, directional technology does not improve localization of sounds. Research has shown that many hearing aid users prefer directional technology for listening in noise.

Some hearing aids automatically switch to a directional mode when noise is detected. Adaptive directional hearing aids automatically tracks a dominant single noise source (e.g., a car passing by someone on a sidewalk), attempting to provide maximum reduction in gain toward the location of the source.

Multiple Channels:

The majority of today's hearing aids have multiple channels. Each channel represents a portion of the frequency range important for understanding speech. One advantage of multiple channels is that features such as gain and compression can be programmed differently to reflect changes in the patient's hearing across frequencies. Multiple channels also are useful for implementing other features such as digital noise reduction and feedback cancellation.

Multiple Memories:

A memory is a location to store hearing aid settings that are designed for a particular listening situation. It is common for hearing aids to have two or three memories. For example, in a hearing aid with three memories, it is common that memory one will be for listening in quiet, memory two will be for listening in noise, and memory three will be for telephone. On the other hand, many hearing aid users find that a single memory works in a variety of listening situations, and only use one memory. Changing memories is accomplished by using a button on the hearing aid or with a remote control device. In most digital hearing aids, it happens automatically.

Telecoils:

With this special circuit, electromagnetic signals can be picked up from the handset of the telephone and amplified in a manner similar to the amplifying function of the hearing aid. Many hearing aid wearers report benefit with this circuit. Telecoils are not available in some smaller custom-made models due to space limitations. Often, hearing aids with multiple memories will devote one memory to the telecoil. In these instruments, the telecoil can be accessed through a push button on the hearing aid or by the use of a remote control.