did you know #1 . . . did you know #2 · did you know #1 . . . about 85% of hearing health care...

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2/4/2014 1 HEARING AID FEATURES ACROSS MANUFACTURERS: WHAT REALLY WORKS AND CLINICAL IMPLICATIONS Todd A. Ricketts, PhD Associate Professor and Director of Graduate Studies Department of Hearing and Speech Sciences Director, Dan Maddox Memorial Hearing Aid Research Laboratory Vanderbilt University Medical Center Nashville, TN Financial Disclosures Financial support for this presentation was provided by the MSHA I have the following financially relevant relationships in the service and/or product communicated, compared, evaluated and/or reviewed in this presentation. Some of the data presented was supported by investigator initiated research grants provided by the Dan Maddox Foundation, Phonak AG, GN Resound, Siemens, Starkey, Oticon, Widex, Persona Medical, Frye Electronics, the Department of Veterans Affairs, and the US National Institute of Disabilities and Rehabilitative Research (NIDRR - DOE) Did You Know #1 . . . About 85% of hearing health care providers have a “favorite” manufacturer (Johnson & Ricketts, 2011) Did You Know #2 . . . Hearing health care providers who have a favorite manufacturer, fit that product to about 80% of their patients. Did You Know #3 . . . Regardless of what company of the “Big Six” they picked, they all reported they picked the company because it had the best technology THEY CAN’T ALL BE RIGHT! How to try to ensure satisfied patients? Examine the Patient’s communication and listening needs and based on the evidence select and adjust features and processing to best address those needs. Counsel regarding use and benefit from technologies to make sure the patients expectations are met. Satisfaction = Expectations Met! 6

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2/4/2014

1

HEARING AID FEATURES

ACROSS MANUFACTURERS:

WHAT REALLY WORKS AND

CLINICAL IMPLICATIONS

Todd A. Ricketts, PhD

Associate Professor and Director of Graduate Studies

Department of Hearing and Speech Sciences

Director, Dan Maddox Memorial Hearing Aid Research Laboratory

Vanderbilt University Medical Center

Nashville, TN

Financial Disclosures

• Financial support for this presentation was provided by

the MSHA

• I have the following financially relevant relationships in the

service and/or product communicated, compared,

evaluated and/or reviewed in this presentation.

• Some of the data presented was supported by investigator initiated

research grants provided by the Dan Maddox Foundation, Phonak

AG, GN Resound, Siemens, Starkey, Oticon, Widex, Persona

Medical, Frye Electronics, the Department of Veterans Affairs, and

the US National Institute of Disabilities and Rehabilitative Research

(NIDRR - DOE)

Did You Know #1 . . .

About 85% of hearing health

care providers have a “favorite”

manufacturer (Johnson &

Ricketts, 2011)

Did You Know #2 . . .

Hearing health care providers

who have a favorite

manufacturer, fit that product to

about 80% of their patients.

Did You Know #3 . . .

Regardless of what company of

the “Big Six” they picked, they

all reported they picked the

company because it had the

best technology

THEY CAN’T

ALL BE RIGHT!

How to try to ensure satisfied patients?

• Examine the Patient’s communication and

listening needs and based on the evidence

select and adjust features and processing to

best address those needs.

• Counsel regarding use and benefit from

technologies to make sure the patients

expectations are met.

• Satisfaction = Expectations Met!

6

2/4/2014

2

Why is Evidence Based Research

Particularly Important in Modern

Hearing Aids?

• 16 Participants compared two devices that were acoustically

identical, except one was described as “ new ” and the other as “

conventional ” . Participants completed a speech-in-noise test,

sound quality ratings, and rated overall personal preference for

both hearing aids.

• Significantly better mean speech-in-noise performance (70.9%

versus 66.8%), and sound quality ratings for the “new” hearing

aid

• 75% expressed an overall preference for the “ new ” hearing aid

- double-blind methodology is optimal.

Piers Dawes , Rachel Hopkins & Kevin J. Munro. Placebo effects in hearing-aid trials are

reliable. International Journal of Audiology 2013; 52: 472–477

What we’re going to do . . .

•Review X different hearing aid features. •Selected based on features for which either the manufacturer or the specific patient, or the listening environment is likely to matter significantly based on the data (or all three).

•Limit our discussion of patient benefit primarily to adults.

•Review some of our recent research and pull in some studies from the recent literature.

•Provide a few clinical tips and techniques along the way.

•What is the true patient benefit in the real

world (our best guess if limited studies

available)?

•A = Real and valid benefit, F = No benefit expected

even theoretically.

•If benefit is present, would it apply to a wide

range of patients?

•A = Nearly all patients; F = you may stumble across a

couple of patients that benefit during your career.

•Would you expect the same benefit from the

products from different manufacturers?

Finally, we’ll grade each feature in 3

different areas…

Interpreting the grades for the third category

• Small or No Difference (SD): Few patients would notice

a difference for that feature among products from

different manufacturers.

• Medium Difference (MD): Many patients would notice a

difference for that feature among products from

different manufacturers.

• Large Difference (LD): Most patients would notice a

difference for that feature among products from

different manufacturers. Or differences are so large that

the feature is aimed at different populations based on

the specific design.

The X features we’ll discuss •Sophisticated Gain Processing

•Complex amplitude compression, sliding gain windows, etc.

•Directional Technology

•Advanced Microphone Array Technologies

•Adaptive Directional, Lobe Steering, Bilateral Beamforming

•Digital Noise Reduction

•Modulation based gain reduction, Fast filtering, adaptive Weiner filtering, etc.

•Digital Feedback Suppression

•Tinnitus Masking

•Bilateral Shared Information

•Remote microphone/FM

•Extended High Frequencies

•Frequency Lowering •Frequency compression, frequency transposition, frequency duplication and lowering

•Trainable Algorithms

•Learning VC, Acclimatization Managers

•Wireless Routing Applications (not sound sharing)

•Rechargeable, advanced remote controls and other cool features?

4

Take Home Points for The 8 Features That Didn’t Make

the Cut •Sophisticated Gain Processing

•Modern versions work pretty well and generally fairly equally when looking at group data. Individual differences are present and generally complicated.

•Some emerging data in the youngest kids

•Digital Noise Reduction

•Improved comfort and preference, still hoping for more

•Tinnitus Masking •We know a lot about it when not in hearing aids, new versions are too new to know if there are other advantages other than packaged in a hearing aid.

•Bilateral Shared Information •Emerging spatialization advantages.

•Remote microphone/FM •They work, lots of questions.

•Extended High Frequencies •Slight benefit and preference in listeners with flatter high frequency loss, hard to provide enough gain.

•Frequency Lowering •On average works in kids – no average benefit in adults

•Newest outcomes less than hoped!

•Trainable Algorithms/ Acclimatization Managers

•May lead to better satisfaction, but starting from a validated and verified prescriptive gain is still critical.

2/4/2014

3

Directional Technology:

How Does It Work?

• The signal from two omnidirectional microphones (or two ports leading to a single microphone diaphragm) is altered to cause attenuation of signals from certain azimuths

• Usually signals from sides or behind are attenuated

• Signal alterations can be made to provide attenuation (polar pattern nulls) for a variety of azimuths.

Directional Technology:

How Does It Work? •The majority of directional hearing aids today are both automatic

and adaptive:

• Automatic: Based on the analysis from the signal

classification system, the hearing aid will automatically

switch to directional or omnidirectional depending on the

listening environment.

• Adaptive: Based on the analysis from the signal

classification system, the polar plot will change in an effort

to maximize the speech signal and minimize the

background noise. This is only possible in twin microphone

directional systems

• The most complex systems do not use discreet

omnidirectional and directional states, but instead slide

from lower to higher directivity depending on assumed

acoustic environment.

Directional Technology:

Potential Benefit?

•Patient must position himself correctly and the directional microphone must be functioning correctly.

•Directional microphones should improve the signal-to-noise ratio by 2-3 dB (20-35%) for many difficult listening situations.

•The actual benefit will depend on distance from the talker, room reverberation, and other factors.

The potential for benefit applies to a wide range of patients:

• Adults with mild-severe hearing loss • (e.g. Pumford et al, 2000; Ricketts, 2000; Ricketts, Lindley & Henry,

2001; Ricketts & Henry, 2002; Ricketts & Hornsby, 2003; Valente et al, 2000)

• Adults with severe-profound hearing loss • (Ricketts & Hornsby, 2006; Ricketts, Henry & Hornsby, 2005)

• Children • (Hawkins & Yacullo, 1984; Ricketts, Galster & Tharpe, 2007; Ricketts

& Picou, 2013)

Directional Technology:

Patient Population?

Other factors that might limit

Directional benefits

• Interaction between visual cues and directional benefit

• Effects of hearing aid coupling type (open versus closed)

• Directional microphone stability over time (quality control)

What About Directional/Beamformer

Benefit with Vision?

• Wu & Bentler (2012)

• Aspell, Picou & Ricketts (2013)

2/4/2014

4

Wu and Bentler (2010) Purpose

• The purpose of the investigation was to examine

directional benefit in environments with low or moderate

reverberation across three common SNRs (+3, +6, +9

and/or +12) for AV presentation modes.

• Selected individuals who struggled in noise (Quick-SIN +8

dB SNR or poorer)

Aspell, Picou & Ricketts (in press)

Results

• Large directional benefits seen in all conditions

• 21-30% (Average: 24.46%)

Hard Medium Easy0

10

20

30

40

50

Signal-to-Noise Ratio

Dir

ecti

on

al B

enef

it (

rau)

Low Reverberation

Moderate Reverberation

Results

• Variable degree of benefit obtained by each participants,

but still large effects

• Also in agreement with Wu & Bentler, 2012 who

demonstrated significant benefit in reverberation.

0

10

20

30

40

50

60

+3 +6 +9 +12

Ben

efi

t Sco

res (ra

u)

Signal-to-Noise Ratio (SNR)

Indivudal Benefit Scores in

Sound Booth

Ss1

Ss2

Ss3

Ss4

Ss5

Ss6

Ss7

Ss8

Ss9

Ss10

Ss11

Ss12

Ss13

-10

0

10

20

30

40

50

60

+3 +6 +9 +12

Ben

efi

t Sco

res (ra

u)

Signal-to-Noise Ratio (SNR)

Indivudal Benefit Scores in

Reverberation

Ss1

Ss2

Ss3

Ss4

Ss5

Ss6

Ss7

Ss8

Ss9

Ss10

Ss11

Ss12

Ss13

What About Coupling?

• Will a directional microphone work in an open fitting?

24

Dir

ectivity I

ndex (

dB

)

2/4/2014

5

Findings from Valente and Mispagel

(2008) comparing OC omnidirectional to

OC directional

-2

-1

0

1

2

3

4

5

6

Listening Conditions

Me

an

RT

S (

dB

)

unaided

omnidirectional

directional

benefit

Unaided Omni Direct Benefit

SO IS THERE POORER PERFORMANCE

IN NOISE FOR DIRECTIONAL OC?

26

N = 280 Participants

(VA RR&D Study)

New Preliminary Data!

• The Effects of Hearing Aid Coupling and Signal

Source Location on Benefit From Different

Microphone Types

Harland, Picou, Hornsby, Tharpe,

& Ricketts (in preparation)

Purpose

• To evaluate the potential interaction between coupling

configuration (open versus closed), signal source location

(on-axis versus off-axis), and microphone type

(omnidirectional, directional, FM plus environmental

microphone) on the speech recognition in noise abilities of

pre-teens and teenagers with hearing loss (10 completed

to date).

Test Environment

• Average reverberation

time (60 dB decay)

within the moderate

range (500-800 ms)

5.1 meters

FM Transmitter

Signal

Source

180°

Signal

Source

1 meter

1 meter

5.9

met

ers

Results – On Axis Listening

-10.0-9.0-8.0-7.0-6.0-5.0-4.0-3.0-2.0-1.00.01.02.03.04.0

OMNI 0° FIXED DIR 0° FM+OM 0°

BK

B-S

IN S

co

re (

dB

)

Microphone Mode

Average SNR-50 Scores Across Conditions

(Speech Front)

Open

Closed

2/4/2014

6

Clinical Implications

• The open fitting reduces speech recognition in noise

performance for all microphone types by about 1 dB (10

percentage points).

• For patients who struggle the most with speech

recognition in noise, fitting with closed coupling may be

preferred to optimize benefit.

Current Conclusions – Directional

Microphones when facing the talker

• In the hearing aids it works in - it works pretty well, even

with vision.

• Do the directional microphones used in hearing aids

general operate as expected, or are their quality control

and/or failure in the field issues we should be concerned

about?

Quality Control

• Maximum directivity (average DI or AI-DI) across instruments varies from about 1.5 dB to about 5.7 dB

• Dirt and damage will affect the average instrument over time affecting directivity and the benefit our patients

Clinical experience suggest nearly all manufacturers continue to have at least some issues with quality control.

• Perhaps as high as 5-10%!

• This happens both with new and repaired instruments.

Effect of Time –

Newer Data From a VA Study • Clinically assessed FBR on all instruments before

fittings and after every two month trial.

• For ITE instruments this was a single trial of

approximately two months.

• For BTE instruments, were refitted on more than one

patient for multiple (up to four) two month trials.

• Pilot work used to define average FBR for each type of

instrument.

• A frequency averaged FBR of 6 dB less than average was

considered a fail.

34

Directional Failure Rate for New

and Fitted Instruments

A need for verification?

36

The Bottom Line: Clinical assessment of directional

properties using a repeatable method is critical for

QUALITY CONTROL!

-15

-10

-5

0

5

10

15

20

010

2030

40

50

60

70

80

90

100

110

120

130

140

150160

170180

190200

210

220

230

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250

260

270

280

290

300

310

320

330340

350

500

1000

2000

4000

2/4/2014

7

Clinical Verification is Critical!

• Consider prior to or at the fitting and at every hearing aid

check up.

• A few options….

• Does it function at all?

• Directional Listening Test

• Does it function in an expected manner?

• Front-to-back ratio (FBR/FSR)

• Specialized Directional tests using hearing aid test equipment

SPECIALIZED TEST BOX

MEASURES OF

DIRECTIVITY

Is Just Front and Back Enough?

Fonix 8000

Advanced features still must be disabled!

The same compression, DNR and automatic

switching issues as with FBR.

Specialized Directional Measure

• Some real ear or test box measures use two signals active at

the same time (e.g. Audioscan) and can circumvent some of

the FBR and polar plot issues such as compression

• DNR issues can also be alleviated by introducing speech as

well

• Therefore it may be preferable if available as a quick clinical test.

40

Verifit Directivity Measure:

Interleaved Signal From “Front”

and “Back” Loudspeaker

Frequency (KHz)

= Main input signal (512 pure tones 7.8Hz apart)

= Secondary input signal (512 pure tones 7.8 Hz apart)= Secondary input signal (512 pure tones 7.8 Hz apart)

An Example of a Test Box Directivity

Measure

42

Good Function in an OC Is Bigger Always Better? No!

2/4/2014

8

Another Example of a Test Box

Directivity Measure: Not So Great

43

Unfortunately, there are some strange

interactions and some considerations!

• Feedback suppression interaction

• Should I use FBR or test box

directivity measures for comparison

across models?

• No – Just quality control!

45

Why not compare across models with

FBR or Test Box Measures?

-40

-20

0

0

30

60

90

120

150

180

210

240

270

300

330

Cardioid Hypercardioid

Theoretical polar

plots – so this is an

oversell.

Compression

interactions as well.

Bilateral Lobe Steering:

How Does it Work? • Lobe steering is NOT an adaptive directional microphone

• The bilateral “direction of focus” is changed through one of

a number of possible methods:

• Bilateral directional control

• Signal sharing

• Decisions about direction of focus are made by:

• Automatic algorithms

• Based on assumed speech of interest direction – so mistakes are

possible

• Manual Control

• Requires user intervention

Some electroacoustic data

from Wu & Bentler

Brand A

Brand B

Speech @ 0; Steady State Noise @ 180

2/4/2014

9

Brand A

Brand B

Speech @ 180; Noise @ 0 Speech @ 90; Noise @ 270

Brand A

Brand B

Some Behavioral Data (HINT sentences from behind in steady noise from front)

0

2

4

6

8

10

12

vs. Omni vs. Dir

Ben

efi

t (d

B -

HIN

T)

Mueller, et al, 2011 Wu and Bentler, 2010

Additional Support (Kuk and Keenan, 2012)

Current Conclusions (Lab):

Bilateral Directional Steering

• For very specific listening situations - it works pretty well.

• Remaining Questions?

• Automatic Switching Accuracy?

• Manual Switching?

• Best and worst environments? Car versus a restaurant

Bilateral beamforming:

How does it work?

• The signals from all four microphones across both hearing aids are used together to form an array with higher directivity.

• Potential problems:

• Need to avoid a monaural signal or binaural cues will be distorted and localization will be destroyed. • Proprietary methods used to preserve binaural cues.

• One method is to only apply the beamformer in the high frequencies which leaves low frequency Interaural timing difference cues intact another attempts to preserve natural ILDs.

2/4/2014

10

Cue Preservation in Slightly (natural)

Directional, Directional and Beamformer?

0 10 20 30 40 50 60 70 80 900

2

4

6

8

10

Azimuth (degrees)

IL

D (

dB

)

Mild

Moderate

Strong

0 10 20 30 40 50 60 70 80 90-0.25

0

0.25

0.5

0.75

1

Azimuth (degrees)

IT

D (

ms)

Mild

Moderate

Strong

Effects of increased

venting on ITD cues

(if audible) and

expected effects.

Potential advantages to a beamformer (N = 18)

Beamformer improves speech recognition about 8-15% in reverberation (compared

to directional) – Picou, Aspell & Ricketts (in press)

(+3, +6, +9, or +12 dB SNR)

Hard Easy0

20

40

60

80

100

Sp

eech

Rec

ogn

itio

n P

erfo

rman

ce (

rau)

Low Reverberation

Hard Easy0

20

40

60

80

100

Sp

eech

Rec

ogn

itio

n P

erfo

rmac

e (r

au)

Moderate Reverberation

Omnidirectional

Directional

Beamformern.s.

n.s.

Are there significant downsides to this

cue-preserving bilateral beamformer

• Higher battery drain

• Gross Localization?

Gross Localization Test Environment

5.5 m

6.5 m

-45ᵒ

-60ᵒ

45ᵒ

60ᵒ

Moderate Reverberation (RT60= 650 ms)

Figure 4

-60 -45 45 600

20

40

60

80

100

120

Speaker Location (degrees)

Lo

caliz

atio

n A

ccura

cy (

%)

Auditory Only

-60 -45 45 600

20

40

60

80

100

120

Speaker Location (degrees)

Lo

caliz

atio

n A

ccura

cy (

%)

Auditory Visual

Moderate

Strong

Moderate

Strong

****

Subjective Preference

• 13 of 18 participants preferred the

beamformer or found it no different than

standard adaptive directional when in noisy

environments (including real “walking” trials).

• Why preferred?

• Most common reasons were “louder” or “easier to hear”

2/4/2014

11

Current Conclusions – Cue-Preserving

Bilateral Beamformer

• Bilateral beamformer has the potential to

provide additional speech recognition

benefits over adaptive directional processing

in moderate reverberation when listener is

facing signal of interest

• Some localization issues, but preference was

not significantly affected

Digital Feedback Suppression:

How Does It Work?

• First, the feedback path is acoustically

modeled in some cases for the individual

patient.

• Ongoing cancellation within the feedback

path is accomplished in a variety of ways

including cancelation and frequency shifting.

Digital Feedback Suppression:

Potential Benefit? • When feedback is minimized or eliminated,

patients are more apt to wear their hearing

aids.

• Acoustic feedback is known to be a stigma

associated with hearing aid use.

• With less feedback, there is a high probability

that more use-gain will be available without

venting alterations.

• The reduction of feedback allows for OC

fittings for greater degrees of hearing loss.

Factors related to assessing feedback

suppression effectiveness

• Magnitude of feedback reduction (e.g.

additional stable gain before feedback,

maximum REIG/REAR before feedback)

• Entrainment

• Some systems are much more susceptible

than others

• Speed in Dynamic FS systems

AGBF for 35 different hearing aid models

(20 were OC) From Ricketts, 2008 (Nov)

0

2

4

6

8

10

12

14

16

18

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35

AG

BF

(d

B)

Model

AGBF (Minimum across 2, 3, & 4 kHz)

10

15

20

25

30

35

40

2000 3000 4000

REI

G (

dB

)

Frequency (Hz)

Brand A Brand B Brand C Brand D

Brand E Brand F Brand G Average

Picking the “right” product can have a big impact

on your success with OC fittings!

Ricketts & Marcrum (2012)

2/4/2014

12

Digital Feedback Suppression

Individual Patient Differences?

• Essentially all patients could potentially

benefit from digital feedback suppression

• Data suggest considerable variability in

effectiveness across individual listeners

Feedback Suppression in Dynamic and

Static Conditions for 14 Participants

Maximum REIG Before Feedback

0

5

10

15

20

25

30

35

40

2000 3000 4000

RE

IG (

dB

)

Frequency (Hz)

Brand A-1 Brand A-2 Brand B Brand C

Distance (phone to ear): Initial point of feedback

and distance for sustained feedback (or touching

ear)

0

5

10

15

20

25

30

35

40

Initial Distance Final Distance

Dis

tan

ce

(m

m)

Distance From Ear For Feedback

Brand A-1 Brand A-2 Brand B Brand C

Note: 7 mm distance is touching the ear. Gain at 75% of AGBF

Duration of Feedback

(Past Initial FB Distance)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Brand A-1 Brand A-2 Brand B Brand C

Du

rati

on

of

Fe

ed

ba

ck

in

Se

co

nd

s

Note: Half Way between Initial and Final Distance. Gain at 75% of AGBF

QUANTIFYING DIGITAL

FEEDBACK SUPPRESSION

IN THE CLINIC

72

2/4/2014

13

Quantifying DFS Clinically with Probe

Microphone #1 • Completion once per model is probably adequate.

• This procedure is easiest using a patient with profound hearing loss in at least one ear.

• AGBF/ Maximum Stable Gain/REAR Before Feedback • Start with maximal venting and a gain configuration and feature

settings that matches a typical hearing loss you fit.

• With FS disabled increase overall gain, while holding the frequency response the same, until you find the point just below feedback.

• Finding feedback in a clinically relevant manner?

• Enable FS and repeat

• Importance of system stability and feedback “quality”!

73

Example: Maximum REAR/ Additional

Gain Before Feedback

74

MGBF DFS/Off

MGBF DFS/On MGBF DFS/On

All Channels to Max

About

8 dB

Quantifying DFS Clinically with Probe

Microphone #2

• Artifacts/distortion/entrainment

• Set up your probe microphone system so that you can listen over the

probe microphone monitor While measuring AGBF or Maximum stable

REAR

• Set gain to the midpoint between MSGBF with FS enabled and

disabled.

• Introduce music (flute concertos can work nicely) and/or pure tones

(pulse on and off with different timing).

• Listen for distortions, new signals

• Consider doing this for all FS settings!

• Max low frequency gain?

75

ISSUES RELATED TO CLINICAL

ASSESSMENT OF FEEDBACK

SUPPRESSION

76

How important are:

1) The FS settings?

2) The specific gain configuration?

3) Other feature settings?

4) Style?

POTENTIAL PROBLEMS FOR

PROBE MICROPHONE

VERIFICATION OF OPEN

FITTINGS

Potential Equalization Problem With

OC Fittings

Sound leaking out of ear is picked up by reference mic

Sound leaking out of ear may be greater than the input to reference mic from loudspeaker

Reference mic thinks it is output from loudspeaker, and so loudspeaker output to ear is then turned down

The result will be less measured hearing aid output (and gain) than is actually present.

Complaint? When I match targets with OC, patients complain that is too sharp/harsh.

78

2/4/2014

14

Test OC products with hearing aid turned off during Probe-mic calibration and the Probe-mic system’s reference mic turned off during verification (stored equalization - some probe microphone manufacturers refer to this as “open” testing). The more gain employed, the bigger the “mistake” will be using concurrent (real time) equalization.

79

A Proven Solution (Lantz et al., 2007)

It is NOT inappropriate to attempt to verify the REAR of open canal style

hearing aids against traditional targets using modern probe microphone

techniques. You just have to use the right technique.

Concurrent vs. Stored equalization

(input = real speech @ 65 dB SPL; hearing aid

gain ~26 dB)

8 dB

Note what happens when you increase gain in the highs! (input = real speech @ 65 dB SPL; hearing aid gain ~34 dB)

16 dB

OC PROBE MICROPHONE

VERIFICATION STEP BY

STEP

Disable Reference Microphone (Frye 7000) Disable Reference Microphone (MedRx

Avant)

Click Open Fit and Select

Calibrate

2/4/2014

15

Disable Reference Microphone (Verefit) Equalize, Level or Calibrate (Depending

on the System)

After

Equalization

the

reference

mic is

disabled

Then Present the Signal and Measure

REAR (Or REAG for calculation of REIG) A Little Head Movement: The Other

Direction

A Little Head Movement: Leaning In

OPEN FITTING FOR

CHILDREN?

2/4/2014

16

Problems with RECD: Is REAR Possible?

• Kim and Ricketts (2013)

• REAR in 22 children aged 4 to 13

• Fitted Both Open (stored equalization) and

Closed (concurrent equalization) using the

Verifit.

• Examined Test – Re-Test Reliability

REAR Test Re-test Standard Deviation

0

0.5

1

1.5

2

2.5

3

3.5

100 1000

Te

st

Re

-te

st

Sta

nd

ard

De

via

tio

n

Frequency (Hz)

OPEN Closed

Conclusions

• No correlation between child’s age and

magnitude of test re-test error.

• Only three children were 4 or 5 yo; however,

REAR appears approximately as reliable in

children 4-13 as in adults, even when fitting OC.

A related issue which applies to all mini-

BTEs including Open: Custom versus

non-custom eartips

• Efficiency issues

• Retention issues

• Durability issues

• Feedback issues

• Is it really still open – subjective versus objective

“open”

• Consistent placement for feedback suppression

94

Wireless Routing:

How Does It Work?

• Signals from external devices (telephone, stereo, TV)

are routed to a single or multiple “middle men”

devices or in some of the newest hearing aids,

directly from smartphone to hearing aid.

Wireless Routing:

How Does It Work?

One large across company

difference is the distance this

signal can be sent; from a few

feet to a few hundred feet. This

affects where the middle

man/men can be placed or if one

is needed at all.

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Wireless Routing:

Potential Benefit? • Improve the SNR for several common listening

situation such as the telephone, television, etc.

• Bilateral signal for devices such as the

telephone

• Convenience for linking to or switching

between multiple external devices

• Smartphone control of the hearing aid

Wireless Routing:

Target Population?

• Applies to a wide range of hearing loss

groups, but best suited for patients who place

a high priority on using external devices.

• Patient also needs to be somewhat “gadget

savvy”

Experiment 1 (Picou and Ricketts, 2011)

• 20 participants with mild-to-moderate SNHL

• Fitted with either open or closed domes

• Listeners seated in a noisy room

• 55 or 65 dB

• Speech recognition tested in several conditions

• Unilateral routing

• Bilateral routing

• Acoustic telephone

• Participants instructed to hold the telephone receiver where they could hear the best

Experiment 1:Results

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0

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Unilateral Signal Bilateral Signal Acoustic Telephone

Open Domes

CS

T S

core (

rau

)

Noise = 55 dBA

Noise = 65 dBA

Experiment 1:Results

-20

-10

0

10

20

30

40

50

60

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80

90

100

110

Unilateral Signal Bilateral Signal Acoustic Telephone

Closed Domes

CST S

core

(ra

u)

Noise = 55 dBA

Noise = 65 dBA

Experiment 2: Rationale (Picou and Ricketts, 2013)

• Experiment 1: Significant advantage for bilateral

wireless routing if using closed eartips. What about

listeners with more hearing loss?

• Typically fitted using more gain and less venting

which is expected to improve the (wireless) signal

to (room) noise ratio.

• May have more difficulty with acoustic telephone

programs due in part to feedback issues.

• What about unilateral t-coil?

• Expected to provide similar speech recognition in

noise performance to unilateral wireless routing.

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Speech Recognition Results

(65 dB SPL room noise)

Speech Recognition Results

(55 dB SPL room noise)

Performance Predictable from SNRs Across

Listening Conditions? Clinical implications

• Acoustic telephone not ideal for listeners with severe

hearing loss

• Unilateral wireless transmission results similar to telecoil

results, but without the positioning constraints

• If you do use wireless routing, bilateral is always better

than unilateral

• But not needed for all listeners, some will prefer to monitor with the

other ear.

FEATURE REPORT CARD

Hearing Aid Feature Real-World

Benefit?

Wide

Applicability?

Benefit

Consistent?

Directional Technology B+ B- MD

Advanced Array Processing

B C LD

Digital Feedback Suppression A- A+ LD

Wireless Technology B A-/C LD

THANK YOU!

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