18ECO124T - HUMAN ASSIST DEVICES UNIT 2 & 3

DSP based is unit 2 12m and it has been repeated in both sets

For unit 3, I have taken one question from each set

12M:

Mention briefly about the DSP Based hearing aids with a neat block diagrams

Since the introduction of the first commercial digital hearing aid in 1996, the possibilities of Digital Signal Processing (DSP) have increasingly been exploited in hearing aids
DSP allows for the implementation of signal processing schemes that have no counterpart in the analog domain

Binaural hearing aid:

Hearing:

Hearing is considered as the most important senses of humans because it connects us to the world.
So hearing loss can have a significant effect on our life, from our work to our connections and enthusiastic prosperity.
A hearing aid is an electro-acoustic gadget, which is intended to increase sound, with the point of making speech more comprehensible.
The fundamental task of the hearing aid is to selectively amplify sound signals to such an extent that the handled sound matches one's audiogram.

Hearing aid design:

The area of hearing aid design of most interest to educators relates to how hearing aids address background noise
Background noise consists of any deleterious sound that interferes with the ability to hear and understand the signal of interest
Most background noises include heating, ventilation and air conditioning systems, fluorescent lights, noise from outdoors..etc…

Analog hearing aid:

Analog hearing aids give straightforward enhancement of the sound grabbed by the microphone and reproduced louder by the receiver or loud speaker.
They have a microchip which enables the device to have settings customized for various listening situations, for example, in a quiet place like in a library, or in a noisy place like in a hotel, or in an expansive region like a soccer field.
The client can easily select these modes when his listening condition changes.

Digital hearing aid:

Digital hearing aids take the sound waves from the microphone and change them to advanced digital binary code by the utilization of digital signal processing (DSP) strategies.
This computerized data would then be able to be controlled in numerous sophisticated ways by the microchip inside the amplifier, before being transformed back into ordinary analog signals and conveyed to the speakers.
The distinctive aspects relating to digital hearing aid systems incorporate auditory compensation, feedback cancellation, noise reduction, speech enhancement

Explain in detail about the sensor technology adapted for the vision impaired with a neat diagram.

The World Health Organization (WHO) reported there are 285 million visually-impaired people worldwide
Among these individuals, there are 39 million who are totally blind
Visual assistive technology is divided into three categories: vision enhancement, vision substitution and vision replacement

The visual replacement category is more complex than the other two categories
However vision enhancement and vision substitution are similar in concept; the difference is that in vision enhancement, the camera input is processed and then the results will be visually displayed
Vision substitution is similar to vision enhancement, yet the result constitutes non-visual display
The main focus is the vision substitution category including its three subcategories: Electronic Travel Aid (ETAs), Electronic Orientation Aid (EOAs) and Position Locator Devices (PLDs)

Electronic travel aids (ETAs)

These are devices that gather information about the surrounding environment and transfer it to the user through sensor cameras, sonar or laser scanners
The rules of ETAs:

Electronic orientation aids (EOAs)

Position locator devices (PLD)

These are devices that determine the precise position that provide critical services for visually-impaired people including

Containing GPS features

Explain briefly about the permanent vision restoration and non-permanent vision restoration.

Main experimental and clinical theories attempted to date for vision rehabilitation after occipital stroke:

(A) Occupational theory includes both substitution and compensation strategies
These therapies may improve quality of life but do not restore lost vision
(B) Visual restoration approaches may be accomplished through home computer-based vision training
The effectiveness of the therapy may depend on timing post stroke, specific training task used and patient compliance
(C) visual training could potentially be enhanced with non-invasive electric brain stimulation
(D) visual training could also potentially be paired with pharmacotherapy to promote greater recovery

Normal vision:

To understand the mechanisms of vision recovery, we first need to look at how ‘normal vision’ works, a complex process
In addition to the healthy functioning of the optics and the retina in the eye, a well-functioning brain is critical
One can think of the eye as a microphone that transforms light rays into electrical impulses
These are then sent via the optic nerve to the brain, where the signals are analyzed and interpreted, creating the subjective sense of a visual experience
Vision is thus not only a product of the eyes, but above all, the result of complex information processing in the brain
Therefore, when the retina is damaged, we should also look at the brain and its untapped capabilities and ask whether the reduced information flow can be improved by means of neuroplasticity to amplify the signals
To use an analogy:

If you walk down the stairs into a dark basement which is illuminated only by a weak light bulb, you cannot see anything until the dark adaptation takes place.
In a similar manner, if less information from the eye reaches the brain, the brain amplifier must adapt to maximize the reduced amount of information.
This circumstance is taken into account; not only the function of the eye must be optimized, but also that of the brain.
The goal is therefore, not only to regulate eye pressure or retinal cell survival, which is what ophthalmologists do with eye drops, or surgery, but also to optimize the brain to maximize the use of residual visual inputs

Thus, while traditional ophthalmology aims to slow down or even prevent the aggravation of the problem, the new holistic, clinical approach of vision therapy is to strengthen residual vision by optimizing the function of the remaining cells and brain networks to strengthen their maximum potential

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