Client: Herb Harmison
Faculty Advisor: Edwin C. Jones Jr.
Team Members:
Hassan Javed Qureshi
Hamdan A K A Al-Mehrezi
Trong Ha Do
Nathan Cory Veen
February 25, 2003
Introductory Materials
Abstract
Advancements in circuit design and electrical devices, like microphones, have molded modern hearing aids to become smaller and better attuned to an individual’s needs. Along with these advancements has come a hefty price to pay for hearing aids. Figure 1 below shows a variety of hearing aids available today.
Figure 1: Expensive hearing aids available today
Many people cannot afford the high cost of these devices and will struggle through life trying to hear the noises around them. Many people also shy away from hearing aids because society today views them as a major fault unlike eyeglasses. Producing an effective, acceptable, and inexpensive hearing aid is the goal of this design team. The hearing aid device will resemble that of a CD player, MP3 player, or a cell phone with a wire connect earpiece and microphone, devices that are accepted in our society today. The approach will be to first design the necessary circuit, then to test the circuit and implement a design to coincide with standards in today’s society, and finally demonstrate our alternative lower cost hearing aid. The hearing aid device will help many who struggle with hearing loss because they cannot afford the cost of advanced hearing aid devices.
Acknowledgement
Herb Harmison, the client for this senior design project, has and will continue to be contributing to this project through technical advice and general feedback. Professor Edwin Jones Jr. is the faculty advisor for this project and will be providing technical advice and general feedback.
Problem Statement
The general problem is to develop a hearing aid device that will be affordable and designed to be acceptable in today’s society. Due to the inexpensive nature of our device and the difference in hearing ability, the hearing aid will have to be able to adjust to each user. Incorporating controls for volume levels, frequency ranges, and the effective range of the microphone into the main unit will provide this flexibility. Finding quality, yet cheap and fashionable, headphones and microphones with an acceptable frequency response will require research and testing. A battery source to run the unit must also be incorporated into the main unit that will be long lasting but not make the main unit uncomfortable to wear due to the weight of the battery.
The general solution and approach to developing a low cost hearing aid device will be to first understand how the ears function and work. Determining the capabilities of the ear and the best operating levels for the ear will set the foundation for determining what components will be used in the hearing aid device. Once these factors are determined, the hearing aid device can be built to meet amplification specifications, the frequency ranges, and the microphone range. Incorporating a fashionable headphone and microphone design will mean developing ways to attach these parts to materials that are worn everyday, like connecting the headphones to an individual’s eyeglasses. To keep the unit at a comfortable weight, small batteries will be used as the power source. To test for acceptability, one group member has a friend and another has a grandmother that has noticeable hearing loss. These individuals would be great for testing the hearing aid.
Operating Environment
The hearing aid device will be able to function in numerous conditions. The optimal area for use will be inside because elements like wind, people talking, and traffic noise will not be picked up by the microphone(s). The unit will still work outside but could be affected by various noises. The unit will work in dusty conditions and in extreme cold and hot climates, like that of Iowa. The device should not be thrown or dropped; doing so could loosen connections and components inside.
Intended User(s) and Intended Use(s)
The intended user for the low cost hearing aid will be for both men and women of any age. The majority of users will be over the age of 50 that have experienced noticeable hearing loss. The headphones could possibly be able to connect to a person’s eyeglasses for more convenience when wearing. The user will need to be able to read directions for controlling the volume, frequency ranges, and microphone levels.
The hearing aid device’s intended use is to aid those with noticeable hearing loss in several environments. These environments include daily conversations inside or outside, watching movies at the theater or television at home, or listening to a message or speech. In general this device will improve the performance of an individuals hearing.
Assumptions and Limitations
The following is a list of assumptions:
· Wires will connect the headphones and microphones to the main unit.
· The user will be able to adjust volume, frequency, and microphone intensity.
· The hearing aid will have stereo sound.
· Primarily elderly people that wear eyeglasses will use the device.
· The microphones could be attached or free standing, depending on situation.
The following is a list of limitations:
· The main unit should weigh around 5 oz. (client requirement)
· The hearing aid device should cost in the range of $100 - $200. (client requirement)
· Use analog technology because digital technology could be too expensive.
· The main unit will be around 5 x 2 x 1 inches in size.
· The decision to use one or two microphones in the circuit design to create the stereo output.
Expected End Product and Other Deliverables
The expected end product will include the main unit where the circuit, controls, and battery will be located. Headphones and microphones will connect to this main unit via wires. The headphones will be designed to attach to eyeglasses for easier wearing and the microphones will be able to attach to clothing. Figure 2 below provides schematic of the basic end product.
Figure 2: The basic components of the hearing aid design
The team members will conduct a test to help the user set the levels of the volume and the different frequency ranges. A user’s manual will also be delivered with the end product, which will contain the products specifications, instructions, and technical support information.
Proposed Approach and Statement of Work
Proposed Approach
This section will cover all the issues of our approach towards the project. It involves requirements, different considerations, management issues and the proposed milestones.
Functional requirements
The main goal of this project is to build a hearing aid with the newest technology, keeping within the limit of the budget. The end product will perform the following functions:
· It should amplify the normal sound to a certain level, which would be audible for the user. The audible sound depends upon the user requirements and differs from user to user.
· It must include an on- off switch. The purpose of this switch is to switch on and off the aid, depending on the user’s requirement.
· Adjustments can be made to the volume. If sounds are soft, the user can "turn up" the volume control. If sounds are loud, the user may "turn down" the volume control.
· It will consist of adjustable controls mounted onto the main case of the hearing aid device for controlling the amplification (i.e., general loudness) and frequency/tonality response (i.e., amount of bass, mid-range or treble emphasis). It is recommended that a health care professional should be consulted when setting these controls for the first time because improper use could case serious damage to a users hearing. The user has the option to purchase and use an auxiliary tone generator, which would allow that user to set these controls. However, these settings will not be as precise and as accurate as seeing a professional.
Constraint considerations
The following are some of the constraints that will be faced in this project:
· Size limitations: Construct a moderate size aid (5 x 2 x 1 inches), keeping in view the client’s requirements and fashion market.
· Weight: Product would be light in weight (5 oz.) for the convenience of the client.
· Easy to Use: The audiologist will adjust part of the circuit and the other half will be by the user. This makes it really easy to use.
· Stereo: This feature is the main requirement of the client. It will help the user to hear the sounds from open environment, as real as they could be.
· Fashion and technology: This project will be the combination of latest technology and fashion.
· Precautions: The hearing aid may not be able to work if exposed to the rain or snow.
Technology considerations
The use of analog technology will probably be the basis for the circuitry. This technology is more appropriate according to the needs of the client. Conventional hearing aids use this technology of linear circuits.
Conventional hearing aids are the basic type of hearing instruments. A conventional (or traditional) hearing aid is different from a programmable analog aid because a computer program does not easily adjust the sound of the instrument. A conventional aid is different from a digital aid because it has an analog circuit.
Technical approach considerations
The approach towards accomplishing the goals in this project is divided into the following categories:
· Research and surveys: This is the necessary part of every project as it gives the insight view of different components and their functions. Acquiring the best components while staying within the limit of the budget will be the goal.
· Collection of materials: Following are some of the components that are needed in this project:
1. Headphones
2. Amplifiers
3. Battery
4. Microphones
Collecting them from different vendors is the part of this project.
· Prototyping and simulation: Build the project according to the prototype, as this is the most appropriate approach to do any project. Then simulate different parts turn be turn.
· Testing: At the end, simulate the whole project and check its performance. This is the final part of the project.
Testing requirements considerations
Several family members and friends will be asked to test the hearing aid device upon the completion. The test will be based on the functionality of the controls, the quality of hearing, the design, and on how comfortable the user is in wearing the device.
Testing of each component will be conducted in order to give the best output.
Testing of headphones: Different headphones from different vendors will be tested. The one that gives the best performance will be selected.
Testing of microphones: The most suitable microphone according to the requirements of the client will be used and tested.
Testing of amplifiers: The amplifier plays the main role in the whole circuitry and therefore is the main part of the project. The required amplifier will be tested with the help of some device.
Testing of battery: The long-life battery will be used after testing.
Testing of the whole project: After completion of the project, it will be tested under different circumstances. It will be tested thoroughly keeping in mind if it fulfills all the requirements of the client and gives the best result.
Security Considerations
There are no security concerns that an outside competitor will gain knowledge of this project because the circuit is not overwhelmingly difficult and has been produced in similar forms for various needs. There are no security considerations related to the operation of the end product.
Intellectual Property considerations
Many of the devices that will be used in this design will be that of intellectual property. The headphones, microphones, and many circuit components are produced already by companies and will need to be used according to their specifications. This will impact the project because less design work will be incorporated, but more testing and research will be performed to find the most compatible components.
Commercialization considerations
The hearing aid design will have a nice comfortable shape that is lightweight (5 oz.). The hearing aid will have good quality sound from affordable headphones and microphones at an affordable price
Possible risk and risk management
There could be harmful effects to a person’s hearing if the product is not set at an appropriate volume level. The design will have cutoff volume that will not allow the sound to reach a level that could harm the users hearing more. Another risk would be the loss of a team member. In the event of this possibility, the remaining team members would make up for the lost member by distributing the lost members work evenly and would meet as a group one more time than regular a week to discuss what the loss members work would have been for that week. The final problem risk is that the design of the hearing aid doesn’t work. In the event of this possibility, the team will work hard first to determine where in the design the error occurs, then conduct research to understand the error, and finally develop a design that corrects the error
Project proposed milestones and evaluation criteria
The milestones presented below will be evaluated based on the percent completed of each task. For each individual task to be called a success a value of 90% complete has been chosen. This means that a percent of 90% complete of the overall project will produce a success. The following are the milestones for this project along with a percentage that represents how much each task is out of the total project.
· Project definition: The main components of this task are defining the problem, uses and users, assumptions and limitations, functional requirements, and constraint considerations. This task is 5% of the total. Completing 4.5% of this task will be viewed as a success.
· Technology considerations and selection: The main components of this task are identification of analog and digital technologies, identification of stereo and mono technologies, selection of components, and technology research. This task is 20% of the total. Completing 18% will be viewed as a success.
· End-product design: The main components of this task are identification of design requirements, design process, and documentation of design. This task is 17% of the total. Completing 15.3% will be viewed as a success.