MSD P13038 Hearing Aid Design Detailed Design Review February 8, 2012

MSD P13038 Hearing Aid Design

Detailed Design ReviewFebruary 8, 2012

Team Members 2.1.13

Alissa Anderson Team Manager

Conor Murphy System Integration Engineer

Ronald Dries Lead Electrical

Kelly Murosky Lead Mechanical

Nanxi Yu EDGE Master

Paula Garcia Secretary

Eric Lew Budget Master

Marbella Vidals Customer Relations

Sarah Brownell Guide

Agenda 2.1.13Project Overview (5 minutes) - Welcome

Mechanical Design Review (30 minutes) - Enclosure review (function, assembly) - Assembly Review- Hot Topic: Assembly Feedback

Electrical Design (40 minutes) - Electrical Feasibility - Circuit Schematic Review- Printed Circuit Board (PCB) Review- Hot Topic: Schematic Review

Software Design (40 minutes) - Software Flowchart Review- Programming In Circuit- Processing Algorithm- Hot Topic: Programming in Circuit

Project Plan (5 minutes) - Critical Path- Budget review

Mechanical

Functional Decomposition (ME) 1.11.13

amplify sound

process sound

capture sound

modify sound

filter sound

adjust by frequency

supply power

store energy

transform energy

output energy

accept energy

interface with user

accept ear

fits comfortably

protects user

resists water and shock

controls volume

manages heat

program device

accepts data

stores data

user input

recognizes input

stores input

adjusts system to input

raise sound level

track power level

modify function to data

output sound

Key Needs: (2) Fits most adult ears ages 15-25 years(3) Device does not draw negative attention (4) Device supports an active lifestyle (7) Device is rechargeable by computer USB

Product Concept 1.2.13

Interface with standard ear tube and ear molds

battery enclosure

round enclosure

transfer module

Round Enclosure (No Transfer Module) 2.1.13

outlet for wires to BTE enclosure

5 way button

up = volume updown = volume

downright = profile up

left = profile downin = power on/off

micro USB opening - to interface with transfer module

pin to interface with transfer module for

stability

pin to interface with transfer module for

stability

holes for microphone sound

capture

CAD Proto 1- Rotation Feature 2.1.13

Top Closed

Top Open

Front Closed

Front Open

Outer blue “ring” rotates about the main enclosure allowing user to hide the micro-USB hole. Rotation is controlled by grey wire stem.

Proto 2 Changes:(1) Update microphone hole locations(2) Improve ring assembly

How to attach Transfer Module 2.1.13

(1) rotate blue ring down

(2) expose micro usb port

(3) add transfer module. module will be secured by

female micro USB (not shown) and stability pins

stability pins

(4) wear and enjoy!

Battery Enclosure 2.1.13

micro USB (power charging)

Batteries slide out of enclosure when they need to be

replaced

wires to round enclosure

Proto 2 Changes:(1) Battery Clips(2) PCB Standoffs

Proto-2 Change List 2.6.13Planned Changes as of February 7, 2012

(1) add PCB standoffs to bottom round enclosure and battery case(2) add standoff location for 5-way switch (3) increase size of transfer module and improve transfer module / enclosure interface(4) update tube interface and solidify ear mold attachment plan(5) Add battery clips

A

B

C

DE

F

G

H

User Renderings 1.2.13

Material Selection 2.6.13

Sabic’s Cycolac acrylonitrile-butadiene-styrene (ABS) thermoplastic resinGrade MG94Superior flow, injection molding ABS Good impact resistanceBest for thin-wall applicationsMedical biocompatibilityGamma and ethylene oxide (EtO) sterilization propertiesFDA and ISO 10993 compliantChemical resistanceFlame-retardancy that meets regulatory and safety standardsHandles temperatures up to 110 CBroad range of colors

Material Properties 2.6.13

Test Plans (ME) 1 of 2 2.1.13

Spec #

Source SpecificationDirection

Units of measure

Marginal Ideal Test Plan

S8CN11, CN12

Maximum temperature at outside surface of device

min oFbody temp

+ 10body temp

Temperature sensor on final product to measure operating

temperatures

S10

CN4, CN6, CN10, CN11

Weight of earpiece min g <15 <12weigh final product

using scale

S18 CN9Attaches to a standard ear

tube and ear moldyes/no

yes/no yes yesTest product with standard ear tub and ear molds

S19 CN14Manufactured cost

(estimated)min $ <2000 <1000

Mathematical Analysis

Test Plans (ME) 2 of 2 2.1.13Spec

#Source Specification

Direction

Units of measure


S9CN2, CN4, CN11

Range of adult ear size accommodated

max percentile25th to

75th5th to 95th

Heuristic Analysis Dimensional

Analysis to prove the final product

S14 CN3

Percent of surveyed people who identify a picture of the device as something other than a hearing aid.

max percent >60 >80 Heuristic Analysis

S15 CN3

Percent of surveyed hard of hearing people who prefer the form of the new device to standard behind the ear

hearing aids


S16 CN3

Percent of surveyed hearing people who would

use the device for Bluetooth or music listening


S17 CN11Percent of surveyed people

who feel the device is comfortable to wear


Key Risks (ME) 2.1.13ID Risk Item Effect Cause

Likelihood

Severity

Importance

Action to Minimize Risk Owner

8

Parts break during system integration

Prototype (or final product) cannot be assembled; schedule pushed back

Failure to work carefully with parts; poor material choice; failure of EE and ME teams to communicate with part sizes

2 3 6

Work carefully with finished parts; During alpha and beta prototypes, work with a variety of materials and companies to find best quality; order multiple prototypes and electrical components to replace broken parts

Conor

9Parts do not assemble

Prototype (or final product) cannot be assembled; schedule pushed back

Failure to review CAD and complete full tolerance analysis; failure of EE and ME teams to communicate with part sizes

2 3 6

Complete full tolerance analysis and CAD review prior to ordering final 3D print

Kelly

22

Unable to create Button Interface that meets space constraints and is water resistant

Cannot interface part electrically; miss waterproof customer need

Poor switch device choice

2 3 6Prototype with button; research more options for waterproofing connection

Ali Anderson, Nanxi Yu

26Rapid Prototyping tolerances

Design will not be with in specifications; parts will not assembly

3D printing company cannot support required tolerances

2 3 6Seek advice from experts. Research companies and obtain quotes.

Kelly Murosky

EE

Functional Decomposition (EE) 1.11.13

amplify sound

process sound

capture sound

modify sound

filter sound

adjust by frequency

supply power

store energy

transform energy

output energy

accept energy

interface with user

accept ear

fits comfortably

protects user

resists water and shockcontrols volume

manages heat

program device

accepts data

stores data

user input

recognizes input

stores input


raise sound level

track power level


output sound

Key Needs: (1) Device amplifies sound(7) Device charges via USB port

Round PCB (EE/CE) 2.1.13

Battery Layout (EE/CE) 2.1.13

MSD 1 Unit Test Plans (EE/CE) 2.1.13Test

EE/CE

Test Description Expected Outcome Equipment Needed

Microphone Unit Test

EE

This test will test the functionality of the microphone. We will setup a microphone and connect its ouputs to an oscilloscope. Then observe the output as we talked into it

We will see what the output of the microphone is and be able to determine if the level of output from the micophone is too high for the ADC on the DSC. Also we will get a better understanding of how the microphone works. Also determine how the outputs of the two mics is different

OscilloscopeMicrophone

Speaker Unit Test

EE

This will test the functionality of the speaker. A speaker will be setup and we will connect its input to a signal generator. We will then be able to observe how the speaker works

The expected outcome of this test is to determine that the speaker functions, and what kind of amplitude is required to make the speaker function.

Waveform GeneratorOscilloscopeSpeaker

Bandpass filter and Pre-Amplification Test

EE

This will test the functionality of the bandpass RC filter and the pre-amplification instrumentation amplifier. We will test the system by applying signals of varying frequency and amplitude, and measuring the output signals produced.

The expected output of the test should be a reduction in amplitude of frequencies outside of our desired range of 200Hz-800Hz, with the amplitude of the output signal before amplification being less than one-half of the input signal. We should also see desired frequencies amplified to a level in which they can be evaluated by the ADCs of the DSC.

Breadboard, Oscilloscope, Waveform Generator, Instrumentation Amplifier, Resistors and capacitors of desired values

Battery Charger Unit Test

EE

The battery charger will be wired up on a breadboard like it will be in the final circuit. We will then apply the correct input voltage to the battery charger circuit and attempt to charge the batteries that we purchased.

This will show us that the battery charger functions properly. This test will be performed by measuring the batteries during charging to see if they are actually charging, then discharging the batteries in a way similar to the device's operation. We can also experiment with the battery charging circuit to make it as optimized as possible.

Battery Charger ICBatteriesBreadboardMultimeter


EE/CE


Battery Charger/ Battery connected to DSC

EE/CEConnect the battery charger circuit/batteries to a breakout board for the DSC

This test will make sure that the DSC can be powered by the batteries, and show that there aren't any problems with the battery charging battery system when connected with the DSC

BatteriesBattery Charger CircuitFreescale DSC Eval BoardMultimeter

Test the 5-Way Tactile Switch

EE/CE

This test will prove the functionality of the switch. The switch will be wired up on a breadboard. Then it will be probed as the different directions are pressed to determine the output of the switch.

We will have a clear understanding of how exactly the switch works after this test. As well as we will know if the switch is active high or active low which will be needed for when we use the switch to detect button presses

5-Way Tactile SwitchMultimeter

Integration Testing Evaluation boards

EE/CE

Connect the microphone, speaker, and switch to the DSC connect the microphone input, and the output of the DSC to an oscilloscope.

This will take the functioning units that we previously tested and begin to test them as a whole. The point of this is to use the microphone to input actual speech to the DSC and observe how the processing algorithm works for actual speech. Changes/tweaks will be made to optimize the output.

OscilloscopeMicrophoneSpeakerFreescale DSC Eval Board5-way Tactile Switch

PCB Testing 1

EE/CE

First protoype PCB's will be connected together and tested to show correct operation of components, Also test programming of DSC

The batteries power the circuit as required, the usb charging functions, the DSC can be programmed and runs the same as when using the eval board.

Initial PCB'sOscilloscopeMultimeter

Round Circuit Schematic 2.1.13

Round PCB Schematic 2.1.13

Battery Circuit Schematic 2.1.13

Back PCB with Planes Shown 2.1.13

Back PCB without Planes Shown 2.1.13

Top Layer of Back Piece PCB 2.1.13

Bottom Layer of Back Piece PCB 2.1.13

Key Risks (EE) 2.1.13ID Risk Item Effect Cause

Likelihood

Severity

Importance

Action to Minimize RiskOwner

27PCB Company cannot cut custom edges

Team will be forced to re-design PCBs to accommodate straight edges; changing the board shape may hinder EE ability to properly route traces

Failure to research PCB process prior to creation

3 3 9

Call PCB company and confirm manufacturing abilities. Change companies or adjust board prior to ordering

Eric

28

PCB software is only supported by a single company (PCB Express)

Team is forced to order board from PCB Express; cannot look for alternative price, manufacturing options, etc.

Failure to research PCB process prior to creation

3 1 3Cannot avoid risk based on team decision to use PCB Express.

Eric

29

PCB Express does not assemble boards

Team will be forced to hand-solder surface mount components

Choosing a company that does not support PCB assembly

3 2 6

Call PCB Express and verify if they support assembly; if they do not, team must investigate surface mount support on campus

Eric

30

Freescale chip requires additional hardware to reprogram

Product loses ability to be reprogramed (deliverable)

Miss-reading the Freescale chip documentation

3 3 9Contact Freescale immediately and research reprograming options.

Ron

CE

Functional Decomposition 1.11.13

amplify sound

process sound

capture sound

modify sound

filter sound

adjust by frequency

supply power

store energy

transform energy

output energy

accept energy

interface with user

accept ear

fits comfortably

protects user

resists water and shockcontrols volume

manages heat

program device

accepts data

stores data

user input

recognizes input

stores input


raise sound level

track power level


output sound

Key Needs: (1) Device amplifies sound(7) Device charges via USB port

Mode Change / Standby Flow Chart (CE) 2.6.13

Volume Flow Chart (CE) 2.6.13

Sound Modification Flowchart (CE) 2.6.13

Programming in Circuit (CE) 2.6.13Programming OptionsJTAG/ONCE connector SCI (Serial Communication Interface)i2CMajor issue is how to program the DSC in the circuit (on the PCB)Possible SolutionsDetachable JTAG connectorUSB to SCIRS232 to SCIJTAG/ONCE also allows for debugging of DSC as well as programmingUSB or RS232 to SCI requires additional hardware that will need to be built in a

separate box.JTAG/ONCE connects to USB port of computer then to the hearing aid.

Processing Algorithm (CE) 2.6.13Basic idea behind amplifying sound for this project is to :- Collect samples of human speech- Take the Fourier transform of the samples once a predetermined number has

been reached- Walk through samples in the frequency domain and multiply by the gain- Take the inverse Fourier transform of the modified data to bring it back to the

time domain- Output result through the DAC to the speaker

Sample code from Freescale to perfom an FFT on values in an ADC buffer

res = dfr16RFFT(pRFFT, (FRAC16 *) &AdcBuffer[AdcReadIndex], (dfr16_sInplaceCRFFT *) &FFTInplaceBuf[0]);

The sample code takes in a signal performs the FFT and outputs the highest frequency to the terminal.


EE/CE


Test ADC/ ADC interrupt

CE

Put a simple signal/sinusoid into the Freescale DSC eval board to determine that the ADC is configured correctly and that an interrupt can be generated and handled. Measure the signal before putting it into the ADC to ensure it does not burn anything

The signal will generate an interrupt on the ADC pin and call and interrupt service handler. This will ensure that we can detect ecternal events coming into the system on the ADC port

SignalGeneratorFreescale DSC Eval BoardOscilloscope/Multimeter

Test GPIO/GPIO interrupts

CE

The switch will be wired up to the GPIO ports defined for the different functions that we would like to implement. We will then move the switch to determine that each of the interrupts is generated as we had design them to work.

If we can detect and handle all of the interrupts from the switch then we know that this functionality is working and the ports and pins that we had chosen for each of the functions is working correctly

5-Way Tactile SwitchFreescale DSC Eval Board

Test Volume Adjust

CE

Put a simple signal into the the ADC of the Eval kit, the interrupts have already been tested at this point so this will be testing the interrupt service routine, or the interrupt handler. The volume button will be pressed up and down to simulate the user changing the volume level

The output signal should vary from the input signal according to if the volume is increased or decreased. The input and output of the system will be shown pn an oscilloscope and the output should avry with the volume level selected.

Signal GeneratorOscilloscope5-Way Tactile SwitchFreescale DSC Eval Board


EE/CE


Test Mode Select

CE

Put a simple signal into the the ADC of the Eval kit, the interrupts have already been tested at this point so this will be testing the interrupt service routine, or the interrupt handler. The mode button will be pressed right and left to simulate the user changing the mode

The outpust signal should vary depending on what mode the user is currently in/switched too. The modes will vary the non volume adjusted gains of the hearing aid, so the signal should vary much like the volume is being adjusted, just with the volume level set to 0.

Signal GeneratorOscilloscope5-Way Tactile SwitchFreescale DSC Eval Board

Test Standby CEPress the tactile switch in to put the hearing aid into a standby/power down mode.

The hearing aid should go into a powered down state and no processing should be done at this point. TO return back into a processing state the switch must be pressed again.

5-Way Tactile SwitchFreescale DSC Eval Board

Initial Sound Processing Test

CE

Put a simple signal into the ADC of the eval kit, measure the input signal and output signal on an oscilloscope to visualize how the sound is being manipulated by the DSC

The output signal should be amplified by a value determined by the gain we would like to have for the system. This will give an indication of how exactly the processing is working on a simple test signal. We can then experiment with the sound processing to tweak it or add to it. With the simple signal it should be easier to implement and see the result of the processing.

OscilloscopeSignal GeneratorFreescale DSC Eval Board

MSD 2 Product Test Plans (EE/CE) 2.1.13Spec

#Source Specification Direction

Units of measure


S1 CN1Lowest level of sound

detectedmin dB <60 <30

Place microphone and speaker into Audiologist Test equipment run low sound scenario and see

hearing aid response

S2 CN1 Frequencies amplified max Hz 300-700085-

8000

Place microphone and speaker into Audiologist Test equipment

and look at response of the hearing aid to the input

S3CN1, CN6

Maximum amplification

target dB 85-95 90Place Mic and Speaker into test equipment, set gain to max and observe output response graph

S4 CN5Levels of volume

adjustmentmax levels 5 20

Â Put simple sinusoid into hearing, probe input and output.

See how output changes with different volume levels

S5 CN7Time to charge

earpiecemin minutes <60 <30

Record the time to charge product

S7 CN7Connects to standard

USB 2.0 computer port

target yes/no yes/no yes

Plug hearing aid into USB 2.0 port. Measure voltage/current

from battery charger to determine if batteries are

charging

S12 CN8Earpiece battery life

at maximum amplification

max hours >16 >48Run product at max power andÂ

record the battery life

Proposed Budget 1.11.13

Item Qty Cost ea. Total

Evaluation Boards 7 $200 $1400

Microphones 5 $0 $0

Microprocessor 3 $5 $15

Amplifier components 1 $70 $70

Speaker 5 $0 $0

USB Interface 1 $20 $20

Rechargeable Battery 10 $15 $150

PCB 4 $100 $400

Acoustic Test Stand 1 $500 $500

3D Printing Costs 7 $75 $525

Customer Survey Incentive

1 $50 $50

Miscellaneous X X $1000

TOTAL $4130

Timeline: Critical Dates 2.1.13

Date Event DRI

Jan 29 order proto 1 enclosure Ali

February 15 Printed Circuit Board (PCB) 1.0 Ordered Conor

February 18 order proto 2 enclosure Ali

March 10 order final PCB Conor

March 18 Order final enclosures for integration Ali

April 1 Start integration and debug ALL

April 26 WORKING PROTOTYPE DUE ALL

May 4 Imagine RIT ALL

May 10 Final MSD Review (Week 10) ALL

Updated Team Risks 2.1.13ID Risk Item Effect Cause L S I Action to Minimize Risk Owner

13

Loss of team member (ex: last minute coop)

Team loses knowledge and creates more work for other team members.

Cause may be due to graduation requirements / personal class choices / personal emergency

2 3 6

Cross train between positions. Team manager should be aware of everyones' projects and responsibilities (in the event that one team member leaves, the team manager can help divide the extra work and reassign responsibilities) by checking edge for on a weekly basis to ensure each member updates their documentation. Prior to exit, exiting member should review with the team and transfer all knowledge (if possible).

Alissa Anderson

14

Project exceeds budget allowance ($5000)

Team can no longer financially continue with project

Team member other then "budget master" made unapproved purchase; parts are more expensive than anticipated; emergency purchases are more expensive due to overnight shipping

1 3 3Track expenses and purchase items; Budget Master makes and records all purchases

Eric Lew

15

Team member overloaded with work outside of MSD

Team loses support from stressed team member

(external to MSD) 2 3 6

team members should be constantly aware and proactive about academic schedules to foresee high stress work weeks. team members should vocalize stress / busy weeks to team and team manager so that their responsbile MSD responsibilities can be reassigned or other team members can assist

Alissa Anderson, Kelly Murosky, Ronald Dries, Conor Murphy, Paula Gracia,Nanxi Yu, Eric Lew, Marbella Vidals

Backup

MatLab 1.11.13Code Overview: amplifies sound and reduces noise for a patient with “ski-slope” hearing loss

Frequency Shaper:

Breaks hearing loss into piecewise functions and calculates the required gain for each section

Applies Fourier Transform on the input signal, and multiplies transformed signal by the required gain function

The Inverse Fourier Transform of the signal converts signal back to the time domain.

Amplitude Shaper:

Output signal is inputted into an amplitude shaper to remove noise and confirms signal is in acceptable (not harmful) range.

Types of Ear Molds 1.9.13

Oticon Intiga Hearing aid with “dome” style earmold

Oticon DigiFocus II Hearing aid with “custom” style earmold

Motorola HK200 Bluetooth Headset, “dome” style earmold

Customer Needs 1.11.13Customer Need Rank Description

CN1 9 The device amplifies sound

CN2 9 The device fits most adult ears ages 15-25years

CN3 9 The device does not draw attention to the user as a hard of hearing individual

CN4 9The device supports an active lifestyle (stays on the ear during everyday activities and light activities)

CN5 9 The device includes a way for the user to adjust the volume while on the ear

CN6 9 The device is safe to use

CN7 9 The device is rechargeable by computer USB port

CN8 3 The power in the earpiece should lasts at least 48 non-continuous hours

CN9 3 The device interfaces with a standard tube and ear mold

CN10 3 The weight of the device is similar to existing earpieces

CN11 3 The device is comfortable to wear

CN12 3 The device does not generate excessive heat during use or charging

CN13 1The device includes an additional method for toggling between functions (for later use to switch between programs or turn on Bluetooth, etc.)

CN14 1 The device has a cost similar to current devices when in production

CN15 0 Optional: The device communicates with a cell phone or music player by Bluetooth

CN16 0 Optional: The device has noise cancellation capabilities

Specifications 1.11.13Spec # Source Specification Direction Units of measure Marginal Ideal Notes DRI

S1 CN1 Lowest level of sound detected min dB <60 <30 lowest range of normal hearing EE

S2 CN1 Frequencies amplified max Hz 300-7000 85-8000marginal values are those used in

radio, 85 is lowest male voiceEE

S3 CN1, CN6 Maximum amplification target dB 85-95 90 max considered safe EE

S4 CN5 Levels of volume adjustment max levels 5 20 adjusted in steps or continuous EE

S5 CN7 Time to charge earpiece min minutes <60 <30 EE

S7 CN7 Connects to standard USB 2.0 computer port target yes/no yes/no yes EE

S8 CN11, CN12Maximum temperature at outside surface of

devicemin oF body temp + 10 body temp MEEE

S9CN2, CN4,

CN11Range of adult ear size accommodated max percentile 25th to 75th

10th to 90th

ISE

S10CN4, CN6,

CN10, CN11Weight of earpiece min g <15 <12

marginal values will depend on ergonomic info

ISE

S12 CN8 Earpiece battery life at maximum amplification max hours >16 >48 EE

S14 CN3Percent of serveyed people who identify a

picture of the device as something other than a hearing aid.

max percent >60 >80team should conduct surveys (at

imagine RIT? thoughts?)ID

S15 CN3Percent of surveyed hard of hearing people who prefer the form of the new device to standard

behind the ear hearing aidsmax percent >50 >75 team should conduct surveys ID

S16 CN3Percent of surveyed hearing people who would use the device for Bluetooth or music listening

max percent >50 >70 team should conduct surveys ID

S17 CN11Percent of surveyed people who feel the device

is comfortable to wearmax percent >60 >80 team should conduct surveys ID

S18 CN9 Attaches to a standard ear tube and ear mold yes/no yes/no yes yes maybe should interview

audiologist for final decisionID

S19 CN14 Manufactured cost (estimated) min $ <2000 <1000not as important in first round of

prototyping, but should be considered

ISE

Proto 2 Change List 2.1.13

Documents

MSD P13038 Hearing Aid Design Detailed Design Review February 8, 2012