Appendix (PRP): Skills Checklist Project Name (tentative): Microphone and sound processing for Industrial Design hearing

aid concept Checklist Completed by (name):

Thomas Adcock

For each discipline, indicate which skills or knowledge will be needed by students working on the associated project, and rank the skills in order of importance (1=highest priority). You may use the same number multiple times to indicate equal rank. Mechanical Engineering

1 3D CAD Aerodynamics

1 MATLAB programming CFD

Machining (basic) Biomaterials

Stress analysis (2D) 2 Vibrations

Statics/dynamic analysis (2D) Combustion engines

Thermodynamics GD&T (geometric dimensioning & tolerancing)

Fluid dynamics (CV) Linear controls

2 LabView (data acquisition, etc.) Composites

Statistics DFM

Robotics (motion control)

FEA Composites

Heat transfer Other:

Modeling of electromechanical & fluid systems Other:

Fatigue & static failure criteria (DME) Other:

3 Specifying machine elements

Reviewed by (ME faculty):

Industrial & Systems Engineering

Statistical analysis of data – regression Shop floor IE – methods, time study

Materials science Programming (C++)

Materials processing – machining lab

Facilities planning – layout, material handling DOE

Production systems design – lean, process improvement

Systems design – product/process design

2 Ergonomics – interface of people & equipment (procedures, training, maintenance)

Data analysis, data mining

1 Math modeling – linear programming), simulation Manufacturing engr.

Project management DFx -- Manuf., environment, sustainability

Engineering economy – ROI Other:

Quality tools – SPC Other:

Production control – scheduling Other:

Reviewed by (ISE faculty):

Electrical Engineering

1 Circuit design: AC/DC converters, regulators, amplifier ckts, analog filter design, FPGA Logic design, sensor bias/support circuitry

1 Digital filter design and implementation, DSP

1 Power systems: selection, analysis, power budget determination

2 Microcontroller selection/application

1 System analysis: frequency analysis (Fourier, Laplace), stability, PID controllers, modulation schemes, VCO’s & mixers, ADC selection

Wireless protocol, component selection

1 Circuit build, test, debug (scopes, DMM, function generators)

Antenna selection (simple design)

Board layout Communication system front end design

2 MATLAB 2 Algorithm design/simulation

PSpice Embedded software design/ implementation

Programming: C, Assembly Other:

Electromagnetics (shielding, interference) Other:

Other:

Reviewed by (EE faculty):

Computer Engineering

1 Digital design (including HDL and FPGA) Wireless networks

2 Software for microcontrollers (including Linux and Windows)

Robotics (guidance, navigation, vision, machine learning, and control)

Device programming: Assembly language, C Concurrent and embedded software

Programming: Java, C++ 2 Embedded and real-time systems

Analog design Digital image processing

Networking and network protocols Computer vision

Scientific computing (including C and MATLAB) Network security

1 Signal processing Other:

Interfacing transducers and actuators to microcontrollers

Other:

Other:

Reviewed by (CE faculty):

Chemical Engineering

Energy and material balances on chemical systems Electrochemistry

Fluid dynamics and Heat transfer Inorganic chemistry

Thermodynamics (traditional and chemical) Environmental science and sustainability

Mass transfer and separation process design: distillation, multistage absorption and stripping, batch and fixed-bed adsorption, liquid-liquid extraction, crystallization, membrane separations.

Advanced material science, polymer science

Chemical reactor design: chemical kinetics, equilibrium, and catalysts.

Surface tension and interfacial phenomena

Engineering lab skills: rheology (in Newtonian and non-Newtonian systems), pressure, temperature, concentration. Pilot lab systems; delivery system assembly including pumps, valves and pressure sensors.

MATLAB and EXCEL: solve complex chemical engineering mathematics problems

Advanced chemistry knowledge: general, physical, and organic

Micro- and nano-scale phenomena and process design

Basic chemistry-based material science

Basic engineering economics Other:

Basic Process Control Other:

Other:

Reviewed by (ChemE faculty):

Design Concept Solutions: Current hearing aids listed by Siemens use directional microphones to reduce ambient noise with the option of adaptive cancellation through an unspecified method. Since the major aspect of this project is the sound processing and noise cancellation the 2 solutions included deal with this aspect are included. Both of these will also to amplify the sound once it is processed. Beam Forming to filter sound:

Beam forming uses the array of microphones to fix the location of a signal in order to provide the microphone array with directional response. The advantage is that it is somewhat simple to implement and provides proven increase in speech intelligibility. (Berghe 1)

This design would use a microphone array placed on more than one hearing aids to receive sound and process it to remove noise from regions of non interest to the user. The microphones will need to be placed as far away from each other as possible in order to maximize the effectiveness of the device. This distance is on the order of the wavelength of the sound being targeted (Berghe 1). The easiest way to implement this filtering method would be with either multiple hearing aids or an auxiliary microphone placed elsewhere on the user. Since the distance to target speech is 10-14cm it is impractical to have both microphones on the same device (Berghe 1).

This design would not need to use directional microphones because the directionality comes from the microphone placement rather than just from the microphones themselves. Of multiple hearing aids or a remote microphone is used there will need to be additional efforts to transfer the sound data between each part. The non-adaptive nature of this method also allows for the use of a microcontroller or DSP chip that is not as powerful as ones needed in adaptive methods. To amplify specific frequencies another DSP chip may be used once the sound is filtered. Advantage: Known to work, does not require directional microphones. Disadvantage: Requires large distance between microphones, requires connections between devices if multiple ones are used. Adaptive noise cancellation using multiple microphones: This method builds upon the traditional method of using directional microphones to target specific areas in receiving sound. It uses 2 directional microphones pointed opposite directions go obtain a target signal (front microphone) and a noise signal (rear microphone) and then uses known algorithms to adaptively filter speech out of the noise signal. The two signals are then processed to remove the “noise” from the desired speech. This method does not need the connections between devices because it can be implemented on a single hearing aid. It does however require more processing power from the DSP chip and may reduce battery life. Since several more powerful DSP chips can also do equalization, the adjustment of amplification levels at different frequencies can be combined on the same DSP chip as the noise cancellation. This is useful because the entire setup will eventually fit in one hearing aid instead of being spread between 2. Schematic of system layout from “An Adaptive noise canceller for hearing aids using two nearby microphones”:

Advantage: Can be implemented within single hearing aid Disadvantage: Complexity and possible increase in computation required, requires expensive directional microphones.

Stakeholders: ● Senior Design Student Team

● Senior Design Selection Committee (faculty approving projects)

● Industrial Design Student Team (Contact is Paula Garcia)

● Campus Audiologist (Lawrence Scott)

● Hard of Hearing End User (Eddie McBride)

● Hearing End User

● Potential product producer if end product goes to market

Engineering analysis: Areas that may require investigation:

● How microphone picks up sound

○ Signal quality

■ Signal Noise Ratio of microphone

■ Total Harmonic Distortion of microphone and amplifier

○ Angular effects

■ Effect of angle on microphone response to sound

○ Frequency effects

■ Effect of frequency on microphone response

○ Voltage of output

● If and How the form factor allows for location of sound sources and to what degree.

○ Microphone placement on hearing aid

○ effect of placement on ability to locate sound sources (is it pinpoint or a general

direction)

● Can this information be used to reduce background noise and by how much and by what means

○ can sound from a target region have sounds from a non target region filtered out

○ what is the most effective way of doing this

○ is it practical to do in real time in a hearing aid

○ will it require too much processing power for a hearing aid

● Adjusting sound for user specific loss characteristics

○ audiologist will need to be consulted on how this specific task is done

○ will need to apply the changes to the processed signal before output

● How can hardware be built to implement these sound processing algorithms

○ Can hardware be designed in the time given

○ Will the hardware be oversized or final sized or virtual (running test mic setups in to a

computer and doing processing there)

○ Will hardware increase cost by an unreasonable amount

○ Can hardware be built for the amount typical for an MSD project

Engineering Questions: Does miniature hardware exist to implement noise cancellation? The device relys on noise cancellation in order to improve upon current devices. Current devices by Seimens offer adaptive cancellation as an option. In order for the desigh concept hearing aid to be sucessful it must implement these technologies. The main concern in terms of feasibility is whether or not these technologies are acheivible. Hearing aid manufacturers are very non descript about the propriatary workings of their devices meaning in order to solve this problem hardware must be sourced from elsewhere. A search for components that will fit both the space restrictions and perform the desired task are crutial. Commercially available hardware was found that fulfils the key functions required to meet the goal of receivin, filtering and amplifying sound. Examples are the VLSI model VS8052 digital signal processing chip and the DPA 4080 miniature directional microphone. (See details on following pages) Does the hardware consume an unreasonable amount of power? This question related to battery life. With current barrery technology the amount of electrical energy that can be stored is a valid concern. From benchmarking the capacities of currnet batteries are estimated, and then compared to the rated worst case power consumption for the processor. This will hopefully show that the processing does not require an unreasonable amount of power for use in this application. The main assumption here is that the processor is the main useer of power. With the selected processing chip having onboard amplification for the output as well as one of the microphones, the only additional major draw would be to preamplify one of the microphones. Due to the high impedence of the input to the processor, this is not assumed to consume a substantial amount of power. Based on this the battery life was estimated at just over 2 days with continuous 24 hour a day use. While this is short of the goal of 1 week, the new charging system being developed by the other group wil midigate this inconvinience. (See details on following pages) Does the Hardware have an unreasonable cost? For MSD projects budget is an important concern. For this particular project an internal grant will be applied for in order to increase the budget for this particularly expensive area. This does not mean that budget shoud not be taken in to account. One of the end goals is a product and lower cost is a benefit. For this analysis the main parts are estimated in cost. This includes the processor, the microphones and the development kits required. An example of a processor that was chosen for this analysis was the VLSI VS8053. This is a reletively small 7x7x1.4mm processing chip that has a reasonable cost of around $15 US and also has an available development board for around $150 USD. Additionally the Texas Instruments audio developer kit was suggested and wioll cost around $500. Finally the microphones need to be both miniature and directional. Examples of such microphones are the DPA4080BM, although there are may others. Thes have a cost of around $550 each. The sound producing element (referred to as the reciever) could be reused form a scrapped obscelete hearing aid for testing. Testing equipment for overall gain is available on campus through NTID. The amplification for the second microphone is a simple analog circuit and is not anticipated to cost a significant amount. What results can adaptive noise cancellation bring in a hearing aid environment? This question is answered through researching results of tests done on the subject. This will give an idea of what to expect as results for this project. The main difference between the implementation in the article and this project is hardware. After the article was written hardware capabilities have increased dramatically, meaning a separate computer is no longer needed to implement noise cancellation. The results are also encouraging, showing an improvement in the ratio of the desired signal to noise. (See details on following pages)

Digital Signal Processing chip: For this project the approach of a digital processor was chosen. This is based on most modern hearing aids being digital. For the overall receiving and amplification, the block diagram below outlines the process.

Several of these functions can be combined on toa single digital signal processing chip. An example of

this is the VSLI VS 8053. Below is a revised block diagram showing which functions can be incorperated

on th the chip.

VS 8053

A to D

A to D

Noise Cancellation

Adjustment for Specific Loss D to A Amplification

Mic. 1

Mic. 2

User Input (Volume)

User input (Cancellation)

Output Receiver

A to D

A to D

Noise Cancellation

Adjustment for Specific Loss

D to A Amplification

Mic. 1

Mic. 2

User Input (Volume)

User input (Cancellation)

Output Receiver

http://www.vlsi.fi/fileadmin/datasheets/vlsi/vs8053.pdf

Below is a block diagram of the selected example processor. This shows how specific functions are

brought on board the chip.

Manufacturer claims chip is capable of doing equalization, adaptive noise cancellation and has the

needed Analog to Digital converters built in. There is also memory on the chip to hold additional

programming if necessary. The user input for volume may be handled by the chip or by an external

amplifier depending on how much amplification is required.

Noise Cancellation

Adjustment for Specific Loss

Amplification Mic. 1

Mic. 2

User Input (Volume)

User input (Cancellation)

Output Receiver

Preamp 1

Preamp 2 optional

Chip only has amplification for a single mic input. Amplifiers can be used to boost the war mic signal to required levels.

Block diagram from VLSI. Chip is ~$15 and developer board kit is ~$150

Chip operates from -30C to 85C Microcontroller?

VLSI model VS8052

Power Consumption Calculations:

Power use provided in specifications sheet to allow for battery and power calculations. Battery of

600mAh

Assume full consumption 24 hours a day (worst case)

The highest non sine test number is used as a worst case.

[600*10^-2 Ah]/[12*10^-3 A] = 50hours = 2.1days

While this is shorter than is desired, the battery system developed by the other team will make

recharging easier, offsetting the difference. This estimate also assumes 24 hour use at full consumption,

so is a worst case scenario.

For “sine test”, this uses capabilities of compressed audio decoding, these will not be used for first run in

this project, but as battery technology improves, this will become more feasible.

[600*10^-2 Ah]/[37*10^-3 A] = 16.2 hours

The main assumption made here is that the main processor is the main consumer of electrical power

since it contains an amplifier capable of driving sound producing devices. The only power consumption

due to amplification that is not handles by the chip is the preamplifier for one of the microphones. This

is estimated to be small due to the low current consumed by the chip input.

Microphone:

The microphone for this device needs to both be small, and directional while maintaining high sound

quality. Microphones convert sound input in to an electrical signal. Usually this signal is low and needs

to be amplified. The sound processing chip has a built in amplifier for one microphone, yet the level of

the second microphone will need to be amplified before entering the chip.

This microphone outputs 20mV/Pa of sound pressure. One Pascal is about 94dB, indicating that the

voltage output from this microphone will be small and need amplification. The desired line in voltage

from the processor spec sheet is 2500mV. The amplitude for the built in amplifier must be less than

140mV, corresponding to 7Pa (140mV / 22mV/Pa = 7Pa =111dB) or 111dB, an extremely high volume

usually found at rock concerts and well above the typical requirement for hearing aids. Based on this,

the built in amplifier should work well with this microphone, but one of the microphones will need pre-

amplification.

dB=10*log10(P/Pref) with the reference pressure being the threshold for hearing (0.00002Pa) and

corresponding to 0dB.

dB Scale Information:

http://www.acoustics.salford.ac.uk/acoustics_info/decibels/

dB to Pa Converter:

http://www.sengpielaudio.com/calculator-soundlevel.htm

Microphone Specifications:

http://pdf.tradelink.dk/dpa/produktark/Produktark_4080-

BM.pdf?xml=http%3a%2f%2fwww.dpamicrophones.com%2fen%2fproducts.aspx%3fc%3dItem%26categ

ory%3d129%26item%3d24061%26xml%3d1

DPA Miniature cardioid or super cardioid microphone

0.2” diameter

With wiring and connector 12g, spec not given for only mic

Microphone performance curve gives directional and frequency effects on response to allow for

implementation of modeling. This particular microphone is strongly directional, allowing for it to receive

sound in a narrow field of direction. Links to microphone and control chip on EDGE

Adaptive noise cancellation:

Excerpt from research article:

These results demonstrate the capability of adaptive noise cancelling technologies. This setup used 2

opposed directional microphones, but ran the processing on a separate computer. Words were

improved 2.4-6.7dB. Every 3dB corresponds to a halving of amplitude. The important aspect on the

above chart is the Signal to Noise Ratio or SNR which is a dB scaled ratio of the signal to the noise.

Images from:

www.whcenter.org http://lh6.googleusercontent.com/public/_uU-t43i_X6hJK_CXbWArFvjAyAQ4h5v9bwmOZa1UZfTrnGDBSFyknL5WfUUnW-5ljG2tEiOgp_yeCcqtESTabcgEA8ygdO0bPVn8KnFR55uLu8f-kDGu5jE8tup5vvSEP7TKq0ZQS68L6YJr1txhGTTJOl_Yy0q3QoArIucDzCkeCz3f-MeRWEJ3zSrnFrrOlvYM551c0f1SNJ0fbqiWk9kzQ http://lh4.googleusercontent.com/public/ZSExU3QM65vt1MLrXz5hzrplxngnQrOOBJt37y3WeIzrAcNp661qSltCCIlYJx5Q_eDOgA5IGN17HkrkhDihH1lLxK30_IE-rtTu7IrSnTPUeCVPZ7tBl5MIiPrwAFSgblaIzoAs9Tuqjh3px9I6VlQ0m44ceUsnaKFSjwiYTdVwP1r50nmb www.jabra.com

Traditional Hearing

Aid I Phone 5

BOSE QC 15 Noise

Cancelling Headphones

Jabra

WAVE

Bluetooth

headset

Noise Cancelling

Passive (directional

microphones) or

adaptive. Yes Yes Yes

Number of Microphones 2 3 Unknown Unknown

Battery Life 1-4 weeks 8 hours 35 hours 6 hours

Cost

Several Thousand

dollars depending

on model $649 $299 $56.99

Weight Varies 112g 192.8g 13g

Battery Capacity 35-600mAh 1400mAh ? ?

Benchmarking Matrix

Pairwise Comparison: Place an

"R" if the row is more important.

Place a "C" if the column is more

important.

Example: bicycle redesign

Fits

in f

orm

Is p

rogr

amm

able

(u

ser)

Is p

rogr

amm

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(au

dio

logi

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Imp

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Fun

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ns

in in

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envi

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men

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rece

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so

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roce

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Has

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atte

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Ro

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ota

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ota

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Rel

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Imp

ort

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Fits in form C C C C C C C 0 0 0 0% 3

Is programmable (user) R R R C C R 4 1 5 18% 2

Is programmable (audiologist) C C C C C 0 1 1 4% 3

Improves clarity C C C R 1 2 3 11% 2

Functions in installed environment C C C 0 3 3 11% 2

receives sound R R 2 5 7 25% 1

amplifies/processes sound R 1 5 6 21% 1

Has sufficient battery Life 0 3 3 11% 2

Column Total 0 1 1 2 3 5 5 3 28 100%

Engineering Metrics Customer Perception

Customer Requirements Cu

stom

er W

eigh

ts

Volu

me

(m^3)

Mas

s (k

g)

Red

uct

ion in N

ois

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B)

Gai

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dB

)

Min

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Sound D

etec

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dB

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Volu

me

Adju

stm

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um

ber

of

Ste

ps)

Hea

t O

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)

Bat

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Lif

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Res

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Oper

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Num

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of

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Fits in form x x

Is programmable (user) x

Is Comfortable x x x

Improves clarity x x

Functions in installed environmnt x x

recieves sound x x

amplifies/processes sound x x x x x

Has sufficient battery Life x

Technical Targets

Res

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Volu

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Hea

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10-2

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2.4

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Microphone and sound processing for Industrial Design hearing aid concept MSDI: 2012_2 MSDII: 2012_3 Project Description: For over 50 years the behind the ear hearing aid has changed very little in terms of design. This is the most popular form of hearing aid for severely hard of hearing users due to the power allowed by its larger size. A group of industrial design students lead by Paula Garcia has created a concept for a new form of hearing aid. This was in an effort to both innovate in terms of design, and to create a form that would avoid the stigma of the current behind the ear design. The result is a new form of above the ear hearing aid. Their research also indicated that clarity of sound was one of the areas that left the most desired in terms of improvement. With these in mind, the goal of this project is to create the microphone setup and sound processing circuitry and algorithms for the new hearing aid. One of the main differences from current hearing aids is microphone placement. This new microphone placement will change the way in which the device can receive sound, requiring new processing. The particular deliverables for this project are a microphone setup integrated in to the industrial design concept form and an external sound processing setup that utilizes components that will in future projects me miniaturized. These will receive the sound from the environment, process it to reduce noise and correct for the user’s specific hearing loss, and output an amplified signal to drive the receiver that produces the sound. Current Tentative MSD Team: Vincent Amuso (Faculty Consultant, signal processing), Mark Kempski

(Tentative Faculty Consultant), Industrial Design Student Team led by Paula Garcia (Stakeholder)

Feasibility: In terms of size, the overall dimensions are similar to current devices, adaptive noise cancellation is an available technology and hardware exists to implement it, project scope avoids miniaturization and integration in this stage of the project.