Future trends In Hearing Aids

7/27/2019 Future trends In Hearing Aids

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Current AND Future

Trends AND Technology

in Fitting Hearing Aids

KUNNAMPALLIL GEJO JOHN,BASLP,MASLP

KUNNAMPALLIL GEJOJOHN,BASLP,MASLP


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Amplification can be prescribed using a formula that linksthe characteristic of a person to the target amplificationcharacteristics. This contrasts with an evaluative approachin which the hearing aid characteristics selected are those

that are empirically observed to best suit the person.Prescriptive formulas can be based on threshold, suprathreshold loudness judgments and the situation in whichthe hearing aids are to be worn.

Future research may focus on determining what thebenefits of hearing aid fitting are and how will each benefitcan be achieved.



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Candidates for

multi-memory hearing aids

Multi-memory hearing aids are not for everyone.Estimates of the proportion of patients who willchoose to use different programs in differentlistening conditions vary from 0% to 81%.

If a person wears hearing aids in only one situation(e.g. listening to television), it is most unlikely thata multi-memory hearing aid will be beneficial. If a

person wears hearing aids in several situations, butthe listening conditions are the same in all thesesituations, it is again unlikely that a multi-memoryhearing aid will be beneficial.



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Consider recommending a multi-memory hearing aid if all threeof the following are true:

The patient plans to wear the hearing aid in at least twosituations where the listening conditions differ.

The patient is willing to switch between programs indifferent environments, and has the physical and mentalcapability to do this. For most multi-memory hearing aids,this will necessitate the patient being willing to carry anduse a remote control.

The patient has a high frequency average loss of greaterthan 55 dB-HL, or, has a baseline insertion gain target at500 Hz of greater than 0 dB (both of these requirements

will be met for the strongest candidates).

Recommending a multi-memory hearing aid



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Prescription issues: present and

future

Which processing strategies work?

The first prescription issue that needs to beaddressed whether a particular type of

amplification should ever be recommended.That is, does this type of amplification haveadvantage for anyone. Despite much researchthe knowledge is limited and the question hasto be addressed again for each new type ofprocessing that appears.



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The second problem is the choice to adequate

evaluation measures. The traditional speech

recognition tests are insensitive for hearing aid

evaluation and may be incapable of demonstratingsome of the advantages to be derived from new

types of hearing aids.

The future progress will require improved

evaluation measures so that the answer to thequestion can be given, whether some type of

processing have any advantage.



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Who can benefit from a particular type of

processing?

Any processing will have disadvantages as well

as advantages. Therefore a prescription issueshow to choose the best types or processing for

each individual. If multiple memories are used,

the choose may be complicated because it may

be desirable to use very different types ofprocessing rather than the variations of

frequency response, in two or more memories.



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A future need is for more research company

different types of processing with a view to

determining how to choose the best type for

particular hearing losses and needs.



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What should be the prescriptive objectives?

Speech intelligibility and loudness variationsare two main objectives of the prescriptiveformula. However, some other factors are alsoimportant such as a natural experience ofenvironmental sounds in music, the ability to

detect and locate sounds and natural feeling ofspatial auditory perception.



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In amplification required to optimize someobjectives may differ from the required to optimaother objectives. It is likely that the bestamplification will be compromise among

optimizing various objectives the assume varyingdegrees of importance for different people and atdifferent times depending on the listenerenvironment and personal preferences.

A major area of research need is to determine whatprescription objectives are important and whatcompromises are likely to be preferred byindividuals under particular circumstances.



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Audibility and speech intelligibility

Audibility has always been a central concept inprescribing amplification; its significance is not

properly appreciated. The relationship ofaudibility to speech intelligibility is exemplifiedin articulation index which is a method forestimating speech intelligibility from audibility.Over the years, the attempts have been made touse the Articulation index in either thedevelopment or evaluation of prescriptive

procedures.



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It is also necessary to account for hearing loss desensitizationwhich may be explained as follows:

If severe hearing losses the articulation index

or predicts better speech intelligibility than isachieved.

If the hearing loss is greatest at the high

frequencies a give SI, at those frequencies willcontribute less to intelligibility than the sameamount of audibility at lower frequencies.



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The general implications of hearing lossdesensitization are that severe hearing losses andsloping high frequency hearing losses require

considerably less high-frequency emphasis thanmight seem logical or indeed is prescribed bysome procedures and that maximizing audibility

over a wide frequency range is not alwaysdesirable.



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However, question remains about the precisenature and size of hearing loss desensitization.For example does the value of a given amount

of audibility at one frequency depend only onhearing level at that frequency or is it alsoinfluenced by the hearing at other frequencies

and to what extent does speech intelligibilitydepend factors other than audibility.



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The significance of audibility for prescribingamplification is much less understood than isgenerally believed and is thus an important

subject for future research.



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Loudness issues:

Some aspects of loudness are vitally importantfor hearing aid prescription. Significant

sounds needs to be made audible but notuncomfortable. Loudness is a majordetermined of preferred gain levels. Therelative loudness of different bands of speechwill influence the total audibility of speech atthe preferred overall loudness level.



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Future research should focus on establishingwhat range of loudness levels, hearing aidwearers prefers rather than assuming that the

normal range is best. The preferred range mayor may not turn out to be predictable frompsychoacoustic measurements.



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Acclimatization to hearing aids:

Acclimatization occurs over several weeks evenfor a moderate change in frequency response. It

depends upon what type of amplification theperson is using. Most of the literature suggeststhat acclimatization effects are small.

With regard to the prescription, one important

question for future research is whetheracclimatization affects the assessment ofamplification measurements/requirements.



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In particular, would people with severe hearinglosses make more use of high frequencyinformation if they had been accustomed to

hearing it better?



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What measurements will be made in future

prescriptions:

Future prescriptive procedures may make useof auditory tests other than those in currentuse speech recognition by listeners withimpaired hearing cannot be fully explained by

audibility, suggesting that other abilities have aratio.



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It is often suggested that frequency resolution shouldbe related to speech recognition, but so far no strongcorrelation has been demonstrated after HTL is

controlled for. Literature demonstrates high correlation between

frequency resolution and HTL. Frequency resolutionmay be a consideration for deciding how many bands

should be used in a multi band hearing aid and indeciding what range it should cover.



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Another measurement which will be used would betemporal resolution. Temporal resolution could be aconsideration for choosing time constants and possible

compression ratios for compression system. Althoughlogical possibilities exist, no definite evidence is presentthat frequency or temporal resolution measures willprove useful for hearing aid prescription.

It is also possible that more analytical types of speechrecognition tests could find a role in future prescriptiveprocedure.



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Such tests could show how the prescription ofspecific phonemes is influenced by variations inaudibility in different frequency bands.

Substantial research would be required to showwhether this approach could lead to a practicalprescriptive procedure and it so develop such a

procedure.



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Tests of sound localization would be anotherfuture development that can be useful in hearingaid prescription especially in the choice of ear

mould type. Such measures could become aregular part of the prescription process.



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Till now hearing aid prescriptions has made littleuse of any formal measures of listeningenvironments, social needs or personal

preferences. To a degree compressioncompensates for changes in listeningenvironments in so far as these involve changing

input levels to hearing aids.



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The advent and multiple memory hearing aidshas drawn attention to the need to considerenvironments, needs any preferences. This

experience may stimulate thinking about howsuch factors could be considered in otheraspects of hearing aid prescription. Methods

need to be developed for assessing these factorsand for research into how they are related toamplification requirements.



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Music and Hearing aids what is in

future?

The most intense components of speech are thelow back vowels e.g. (a) in the father. At thelevel of the listeners ear these sounds even it

shouted, rarely exceed 85 dB SPL and are moretypically 75-82 dB SPL. In contrast the moreintense elements of music measured at the sameear level location are in the order of 100-110 dB

SPL with occasional peaks about 118 dB SPL.This is true not only of rock, but classical musicas well.



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Since most engineers have had speech input inmind when designing hearing aid, it isunderstandable that the peak input limiting

level of hearing aids has been set to about 85dB SPL. Peak clipping or limiting may occur atvarious points in a hearing aid, but if it occurs

before the controlling elements, or the NDconverter, adjusting hearing aids setting will notprove it.



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Hearing aids are normally designed so that thisdoes not happen for the peak levels encounteredin speech but the peak levels encountered in

music may well cause clipping in the early stapesof the hearing aid amplifier. The parameter isnot found on hearing aid specifications sheet.

So in future there is a need to develop theprescription and the technology toaccommodate for music perception.


Manufacturer specific prescription


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Manufacturer specific prescription

procedures: Is there any need of

validation in future: Most programmable and digital hearing aids are fitted

with device specific software. The software is used to

calculate the required amplification and to program theaid to match the prescription.

There is no problem as such to use the proceduresdeveloped by manufacturers. Such procedures are

based on research conducted by or for themanufacturers, in collaboration with independentresearchers.



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The procedures are subjected to expert scrutinythrough the normal publication and reviewprocesses and are validated by independent

research. However, scientific concerns are present, when

the procedures developed by manufacturers arenot open for independent validation. Theproblem for the audiologist is that he cantdecide what amplification is best for the patient.



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Indeed the Audiologist may not know whatamplification is provided. It is therefore difficultto know whether the fitting formula is generally

acceptable or whether it should be varied for aparticular individual.



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One more scientific concern is that somemanufacturers fitting method may not be verybest or may be of unknown validity. The

manufacturers procedure may be less likely tobe published and if so will not to accessible forvalidation studies. So, in future there is a need

for the validation of all the prescriptiveprocedures.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


34/100

Such research needs to examine the validity ofdifferent prescriptive rationales each of whichcould be used as the basis for a number of

specific procedures. In addition each procedureneed to be validated in its final form becauseinevitably sources of error will occur in

calculations, measurements and assumptionsneeded to translate a rationale in to practicalprocedures.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


35/100

A challenge for the future is to assess the validityof prescription concepts such as normalizingloudness, independently of the validity of any

particular procedure

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


36/100

Future possibilities in ratings and

quality judgements

Absolute ratings of speech quality orintelligibility and paired comparison preferencejudgments of speech quality or intelligibility have

often used in research studies over the last 15years but have been used clinically except in veryinformal ways.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


37/100

Hearing aids are increasingly using devices andalgorithms aimed at reducing the effects ofbackground noise. These include directional

microphones, switchable dual microphone,directional microphones, low-frequencycompression circuits and multi channel aids

where the gain in each channel depends on theestimated signal and noise levels within eachchannel.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


38/100

These devise thus affect speech intelligibility andsound quality in different ways, and at presentno validated rules exist for saying which content

requires which processing scheme under whichacoustic conditions. Whenever there are noreliable studies for prescription an increased

emphasis must be placed on empirical evaluationand fine tuning.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


39/100

Therefore in future increased use of moreformal clinical evaluations using pairedcomparison ratings of sound quality or speech

intelligibility is expected. Such comparisons willrequire appropriate stimuli (e.g. continuousdiscourse against a variety of background noises)and knowledge of which types of noises and

signal to noise ratios are most useful forexamining the advantages of differentprocessing schemes in the hearing clinic.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


40/100

Research aimed at acquiring this knowledge willprovide a start on forming prescriptive rules thatmay eventually make the subjective evaluations

unnecessary.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


41/100

Hearing aid software predictive gain

values: how accurate are they?

With the advent of digitally programmable anddigital signal processing hearing aids, theclinician is offered a variety of choices for how

to view hearing aid performance in the softwareprovided by hearing aid manufacturers. On theprogramming screen one can choose to display

how the hearing aid is programmed in a numberof ways depending on the manufacturer

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


42/100

Options found in NOAH programming modules include:

2- cc gain

2- cc output

2 ccSPL

2- cc SPLogram

insertion gain

simulated insertion gain KEMAR gain

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


43/100

amplified long term speech spectrum

real ear SPLogram

Ear simulator gain

simulated real ear SPL

Real-ear aided gain.

None of these on screen representation have

been made with the actual hearing aid; ratherthey represent simulations based on average andexpected performance values.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


44/100

Since the audiologists sees these simulatedvalues while programming and adjusting hearingaid, he or she may be tempted to believe that the

computer screen values are for the specifichearing aid programmed for the specific patientbeing fitted with the device.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


45/100

Unfortunately this is not the case. The 2 cccoupler gain values are what the manufacture isspecifying as the standard for the model, not for

the particular device being programmed. Giventolerances of components such as themicrophone and receiver, the values in hearing

aid could vary as much as plus or minus 5 dBsome frequencies.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP

d d f


46/100

Pediatric hearing aid fitting with

non-linear hearing aids

The basic problem of pediatric population is tofill the missing information than do the olderindividuals whose hearing loss occurred after

they had acquired language. Before fitting ofnon-linear instruments on a child lets examinehow the non linear instrument meets the basic

amplification goals.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


47/100

The hearing aid gain is set so that conversationalspeech is audible and the main output is setbelow the wearers comfort level. When the

listeners try to hear soft speech, they areinstructed to turn down the volume control

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


48/100

A non-linear hearing aid adjusts its gain basedon the input level. In single channel non-linearinstruments the loudest input signal controls

the overall gain of the hearing aid. For example,in a room where an air conditioner generatesloud, low frequency noise, the single channelprocessor will turn and the gain across all

frequencies. This is of course reduces theaudibility of all inputs including high frequencysounds.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


49/100

To allow for independent gain control in thespecific frequency regions, the hearing aid musthave multiple channels. In the condition of air

conditioner a three channel non linear hearingaid would reduce pain in the low frequencychannel without changing the gain in the mid

and high frequency channels. The processingmay allow more gain for soft inputs such as highfrequency speech sounds (e.g. /s/ and /f/).

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


50/100

Another consideration with hearing aids isensuring the audibility of soft sounds. Oneapproach is to lower the compression threshold

of the nonlinear hearing aid. When this is doneonly the gain for the low input sounds isincreased while gain for conversational and loud

speech remains as prescribed for the hearingloss.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP

Compatibility of hearing aids with


51/100

Compatibility of hearing aids withdigital telephones or other electronic

device The electronic devices and mobile phones causes

interference to the hearing aids, audiologist will

need to consider whether the hearing aids they

prescribe are compatible with the other electronic

device that the hearing aid wearer wishes to use

will come into close contact with. Indeed the

audiologist should be considering how otherdevices can be used, alone or in conjunction with

hearing aids to optimize the communicative

efficiency of the patient.KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


52/100

Consequently more and more hearing aids willbecome usable with digital mobile phones.However, it is likely to be a long time and

perhaps will never happen, before all types ofhearing aids can be used with all types ofphones. The audiologist will therefore need to

consider the immunity question in the hearingaid selection and evaluation process

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


53/100

The Bluetooth Hearing Aid

Bluetooth enabled hearing aids use this

wireless technology twofold. Bluetooth

wireless technology allows for

communication between two hearing aids.This helps to get the most natural hearing

enhancement possible. The two hearing aids

"talk" to each other to make instantaneousenhancements to improve hearing.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


54/100

Another exciting function of Bluetooth

enabled hearing aids is wireless connectivity

with other Bluetooth enabled devices such

as cell phones and music players. Thistechnology is a vast improvement over

hearing aids in the past which were often

incompatible with other devices.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


55/100

The Future

Both hearing aid manufacturers and headsetmanufacturers will be moving forward and closertogether as they recognize the need and demandfor universal hearing assistance products. Productsolutions that incorporate the effectiveness of the

wireless headset and the amplification and sound-shaping of hearing aids will provide audiologists

with an affordable, self-programmable solutionthat might very well initiate a change in thebusiness model of Audiology practices.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


56/100

The integration of ALDs and Bluetoothheadsets will offer greatly improved hearingcapabilities for users. The hearing aid becomes a

multi-use device that no longer identifies peopleas hard of hearing, but becomes thecommunication device of the future. This

universally-designed solution will become the"must-have" communication device that keepspeople connected anywhere, anytime.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


57/100

Audiologists will be in a position to offerhearing solutions that are self-programmableand more affordable. The stigma of wearing

hearing aids will fade away as the perceptions oftechnology transform from "hearing aid" to"communication device."

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


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"The convergence of Bluetooth, ALDs andhearing instrument technologies will change theperception of the public about hearing assistance

and will impact product and service deliverychannels.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


59/100

Fashionable hearing aids

Called 'designer' hearing aids. "The ideas on displayinclude a remote control to block out irritating sounds,

a device to enable people to have a clear conversationin a noisy bar, and hearing aids designed as fashionablejewellery or must-have gadgets. Another concept,known as the Goldfish, instantly replays the previous

10 seconds of sound to the wearer in case they havefailed to catch someone's name. It is based on the ideathat goldfish only have 10 seconds of memory. "

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


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ARTICLES:

New Fitting Tools and Processing Strategies

Anna O'Brien, MAud, Lorrie Scheller, MS, and

Tom Scheller, BSEE

A technical review of a new hearing

instrument that uses unified signal

processing designed to reduce spectral

smearing and features a number ofadvanced software-based fitting tools.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


61/100

In recent years, the challenge among hearing

instrument manufacturers has been to create a

hearing system that operates in a manner similar to

the human ear, offering natural sound quality in amultitude of listening situations, functioning

automatically, and adapting instantaneously to

every change in the sound environment. Listening

comfort, feedback control, elimination of occlusionand flexibility to adjust to the wearers needs also

have been primary developmental considerations.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


62/100

Ear, Nose and Throat Clinic at the UniversityHospital in Zurich to develop a new non-linearapproach to hearing loss compensation. The

result is a new-generation device called Symbiowhich features a processing scheme designed towork differently from other products on the

market.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


63/100

Speech in Focus: Using Signal Processing

Hearing loss is probably the most isolating sensoryimpairment people experience. In addition to loss ofaudibility, one of the most critical deficits is increased

susceptibility to noise. This is largely due to the fact thatsensorineural hearing impairment causes abnormally broadauditory filters due to loss of outer hair cell function. Themain social consequence of hearing loss is increaseddifficulty in understanding speechespecially in the

presence of competing noise. This difficulty is most likely

due to a combination of reduced audibility and loss offrequency selectivity.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


64/100

Hearing instruments are effective in increasingthe audibility of sounds; however, they cannotreliably alleviate the effects of reduced frequency

selectivity. This results in the often heardcomment that hearing instruments improvespeech understanding in quiet environments, but

are not very effective when there is backgroundnoise.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


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Graphic illustration of multi channel versus a

unified signal processing approach.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


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Processing schemes with a large number of channelsmay reduce the spectral contrasts in the speech signal.

This spectral smearing has been found to significantlyreduce understanding of speech in both quiet and

noise, and may also reduce sound quality. In fact, vanSchijndel et al. found that distorted coding of spectralcues was the main factor associated with reducedspeech discrimination in noise for hearing impaired

subjects. Distorted coding of spectral cues had greaternegative impact than distorted temporal or distortedintensity cue coding.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


67/100

A unified signal processing approach called CASI(Continuously Adaptive Speech Integrity) is utilized inSymbio. With this approach, flexible input-dependentfilter characteristics are applied to the whole signal,

allowing frequency-dependent compression withoutsplitting the signal into channels. This approach tosignal processing is designed to provide the benefits ofmultichannel amplification (ie, extremely flexible

frequency and compression adjustment), but withoutthe drawbacks and potential degradation of the speechsignal caused by spectral smearing.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


68/100

Schematic of the hearing instrument and external feedback path. The panel onthe left presents the gain path through the hearing instrument, with the Adaptive

Feedback Canceller active. The panel on the right represents the feedback path (eg,

leakage through a vent or around the shell/ear moldKUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


69/100

The Adaptive Feedback Canceller works bycomparing the hearing instrument output withthe input from the hearing instrument

microphone, determining which portion of themicrophone signal is feedback, and subtractingthis from the incoming signal prior to the

amplification block (Figure) .In this way, theincoming signal is cleansed of feedback, and

the desired gain is applied to the signal.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


70/100

Dynamic Frequency Mapping. Traditionally,hearing care professionals have looked at graphsof dBHL vs frequency and/or graphs of input

vs output. To adjust the instrument response,modifications are made to the frequencyresponse or the compression (input/output).

Because these two responses are intrinsicallylinked, a change in one always results in ahidden change in the other.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


71/100

Dynamic Frequency mapping software.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


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73/100

The hearing instrument system has been

developed to combine the advantages of samplesounds with in situ verification of the signal

level, ensuring greater accuracy in fine tuning.

This is meant to provide more accuracy thansystems containing a single calibration signal.

The situational verification tool system is

available for use at any stage of the fitting, but is

also integrated with the Client Interactive

Fitting Assistant to help zero-in on specific

frequency areas that the client finds

unsatisfactor ..KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


74/100

Intuitive software leads the dispenserthrough a set of proposed adjustments that

can then be evaluated by the client, allowing

quick, easy and accurate adjustment of theinstrument response. This is designed to

provide a more controlled and accurate

approach to fine-tuning, increasing theprobability of client satisfaction

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


75/100

Clinical verification of a hearing aid with artificialintelligence

Mark C. Flynn & Thomas Lunner

Artificial intelligence uses parallel processing todetermine simultaneously the best solution fromthe full range of processing options. The decisionmaking is based on which solution provides thebest speech-go-noise ratio (SpNR). Applying AI tohearing aids allows new audiologic solutions to beapplied through complex, problem-solvingalgorithms.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


76/100

Syncro, which was introduced in 2004, is builton a new digital platform that implementsadvanced adaptive directionality, noise

management, and wide dynamic rangecompression. Artificial intelligence is thefoundation of the voice priority processing(VPP) system, which oversees three signal

processing approaches: Multiband adaptivedirectionality, Tri state noise management, andvoice aligned compression.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


77/100

All these systems are designed to work insynergy to optimize the signal progressively,with the priority being to supply the best

possible speech understanding. The unity ofthis signal processing goal, combined withdecision making through parallel processing, is

intended to ensure that correct decisions arebeing made and that all systems are workingtoward improving speech understanding in noise

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


78/100

syncro provided significant benefits over otheradvanced digital hearing instruments, including Adaptoand participants own hearing aids. These benefits

include greatly improved speech understanding scoresin noise and reported improvements in subjects daily

listening environment.

In terms of speech understanding, the difference

between the test and the reference hearing aid weregreater than 2 dB (SBR).

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


79/100

Given that each 1 dB in SNR equals an approximateincrease in speech understanding of 10%, this indicatesthat syncro delivers approximately 20% grater speechunderstanding than the reference instrument.

To put this in perspective, the reference instrument(Adapto) recently demonstrated the best speechunderstanding in quiet and noise in a blind comparison

with two other levels of technology (WDRC digital andanalog). Therefore, one can clearly see the

improvement in speech understanding delivered by ahearing aid built on a new platform incorporatingartificial intelligence.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


80/100

In terms of user preferences, the significant reportedbenefits were in complex listening environments (e.g.speech in traffic or multiple talkers).

It is in such situations that we would expect the parallelprocessing to deliver better speech understanding andgreater comfort than other digital platforms through itsability to select from a vast array of possible choices the

solution that provides the best possible speech-to-noiseratio.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


81/100

These gains in speech understanding did not come atthe expense of other dimensions such as sound qualityand comfort. Therefore, one need not view hearingaids as being either speech-focused or comfort-focused.

The results show that the use of AI can enable ahearing aid to deliver excellent speech understanding in

various environments while at the same time increasing

a users perception of comfort and overall soundquality.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


82/100

Importantly, the results for the speech understanding-in-noise test evaluated one area of contention. That is

whether or not increased vent size (i.e. OpenEarAcoustics), which provides relief from occlusion, may

remove the benefit of directional microphones. study demonstrates clearly that collection vents with an

average faceplate size of 2.2 mm continue to providesignificant directional benefit. Directional benefit

remains possible with Syncro because the hearing aidmicrophone system is specifically designed to work

with Open Ear Acoustics.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


83/100

In terms of directionality, the results provide supportfor the split-directional mode. While the first band (ofthe four) is held in omni directional mode, the resultsdemonstrated that users were able to gain a significantdirectional benefit.

The split-directionality provides a transparent transitionbetween the omni directional and full-directional

modes, which allows the implementation ofdirectionality at lower input levels than would bepossible otherwise.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


84/100

In summary, it is crucial to remember that observeddifferences between the standard digital hearinginstruments and those built on a platform of parallelprocessing on measures of performance in backgroundnoise and complex listening situations.

While standard instruments will use single pieces ofinformation in trying to predict the auditoryenvironment, syncro uses parallel processing to analyzemultiple processing options and select the best solution.

The underlying processing strategy is to maximize thespeech-to-noise ratio at all times and thereby optimizespeech understanding.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


85/100

Hearing Aids for Musicians

Marshall Chasin, AuD

Understanding and managing the four physicaldifferences between speech and music allowsthe hearing care professional to approximate thecorrect electro acoustic parameters and enhance

the enjoyment of listening to music.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


86/100

When comparing music to speech, there are fouressential physical differences that warrantconsideration during a hearing aid (or cochlear

implant) fitting. Understanding these differencesand selecting appropriate hearing aid circuitrywill help to optimize the enjoyment of music for

the hard-of-hearing listener. This applies equallyto those who are musicians as to those who liketo listen to (sometimes loud) music.

KUNNAMPALLIL GEJO

JOHN,BASLP,MASLP


87/100

In most cases, regardless of the music program in thehearing aid, if the front ends is distorting (because ofmusics more intense input), nothing implemented later

in a hearing aid can improve the situation.

Understanding and managing the four physicaldifferences between speech and music will allow thehearing health care professional to approximate the

electro acoustic parameters to provide maximumenjoyment of music for musicians and music-lovers.

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Acoustic Structure of Musicfour primary physical differences betweenspeech and music are:

The long-term spectrum of music vs speech.

Differing overall intensities.

Crest factors.

Phonetic vs. phonemic perceptual requirements.

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One Channel is Best for MusicIn sharp contrast to hearing speech (especially innoise), one channelor, equivalently, many

channels with the same compression ratios andknee pointsappears to be the appropriatechoice for hearing music. This recommendation

derives from clinical work with hundreds ofhard-of-hearing musicians over the past 20years.

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Unlike speech, for most types of music the relative balancebetween the lower frequency fundamental energy and the higherfrequency harmonics is crucial. High fidelity music is related tomany parameters, one of which is the audibility of the higherfrequency harmonics at the correct amplitude.

Poor fidelity can result from the intensity of these harmonicsbeing too low or too high. A multi-channel hearing aid that usesdiffering activation points and differing degrees of compressionfor various channels runs the distinct risk of severely altering this

important low-frequency (fundamental)/high-frequency(harmonic) balance

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. Subsequently a music program within ahearing aid should be one channel orequivalently a multi-channel system where all

compression parameters are set in a similarfashion. It has been suggested that, in some bassheavy situations, a two-channel system may be

useful with the lower frequency channel set at500 Hz with greater attenuation at higher inputlevels (L. Revit, personal communication, 2004).

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The clinical rules of thumb for setting compressionparameters for speech are rather straightforward. Thecompression detectors are set based on the crest factorof speech which is on the order of 12 dB (eg, as

discussed earlier, the peaks are 12 dB more intense thanthe RMS).

For speech, compression systems function to limitoverly intense outputs and to ensure that soft sounds

are heard as soft sounds, medium sounds are heard asmedium sounds, and intense sounds are heard asintense (but not uncomfortable) sounds.

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In short, these systems take the dynamic range ofspeech (30-35 dB) and alter it to correspond with thedynamic range of the hard-of-hearing person. And,there is no inherent reason why a wide dynamic rangecompression (WDRC) system that works well for aclient with speech as input, should not also work wellfor music.

However, the dynamic range of music is typically muchgreater than that of speechtypically being on theorder of 80-100 dB.

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if the hearing aid utilizes a peak detector toactivate the compression circuit, the detector ina music program should be set about 5-8 dB

higher than for speech. This is related to thelarger crest factor of music (18 dB vs. 12 dB forspeech), and care should be taken that these

peaks do not activate the compression circuitprematurely.

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Feedback reduction systems. In most cases, since the spectralintensity of music is greater than that for speech, feedback is notan issue. The gain of the hearing aid for these higher-level inputsis typically less than that for speech.

However, if feedback reduction is required, or the feedbackcircuit cannot be disabled in a music program (as it can be forexample, in the Bernafon ICOS) then those systems thatutilize a gain reduction method (eg, Phonak Perseo or WidexDiva, although the Widex Diva only uses this approach for

the music program) would be the best for music.

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Noise reduction systems. Like feedback reductionsystems, it would be best to disable the noise reductionsystem when listening to music. Typically, the signal tonoise ratio (SNR) is quite favorable when listening to

music, so noise reduction is unnecessary. However, for some hearing aids, the noise reduction

system cannot be disabled, and since the primarybenefit for noise reduction systems seems to be for

improving listening comfort rather than reducing noise,choosing an approach for music that has minimal effectmay be beneficial for a music program.

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Most noise reduction systems in use today use a form ofmodulation detection. The modulation is simply the changingfrom quiet to more intense portions in a wave form. The rate at

which it does this each second is called the modulation rate. Forspeech, it is roughly the number of times that one opens and

closes ones mouth every second and has most of its response inthe 4-6 Hz region.

The modulation depth is the difference in decibels between thequietest and most intense elements. For speech this is typically

30-35 dB . For noise the modulation rate is typically very low(


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DefiningThe Music ProgramIn conclusion, a music program, or a set of optimal electroacoustic parameters for enjoying music would include:

1) A sufficiently high peak input limiting level so more intensecomponents of music are not distorted at the front end of thehearing aid.

2) Either a single channel or a multichannel system in which allchannels are set for similar compression ratios and knee points.

3) A compression system similar to the speech-based

compression system with an RMS detector compression schemeand with a knee point 5-8 dB higher if the hearing aid uses apeak compression detector.

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4) A disabled feedback reduction system, or a feedbackreduction system that uses gain reduction or a moresophisticated form of phase feedback cancellation(either one with short and long attack times or one that

only operates on a restricted range of frequencies suchas over 2000 Hz).

5) If the noise reduction system cannot be disabled, acircuit that distinguishes between low (4-6 Hz) and high

(10-100 Hz) modulation rates may be useful fordifferentiating speech from music, and automaticallyturning on a music program.

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Thank you.

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Future trends In Hearing Aids