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Fitting and Dispensing > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Overview of a proper fitting

A
  1. calibrate verification system
  2. otoscopy and probe mic placement
  3. measure RECD
  4. hearing aid placed over probe mic (inside the ear)
  5. select prescriptive formula/rationale on verification system
  6. run specific types of stimuli and record what the hearing aid is doing in the ear
  7. adjust gain in the manufacturer software
    8.re-run stimuli and keeping adjusting until targets are met
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2
Q

Probe tube calibration for verifit 2

A
  1. select on-ear calibration
  2. select right or left
  3. run calibration
  4. repeat for other side
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3
Q

What are the 6 methods for placing probe tubes?

A
  1. visually assisted positioning
  2. acoustically assisted positioning
  3. average length method
  4. geometric positioning
  5. bump and pull
  6. audioscan probe guide
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4
Q

Real ear dial difference (REDD)

A

-the difference between the intensity setting in the HL on the audiometer dial and the output in the ear canal

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5
Q

Reference equivalent thresholds in SPL (RETSPL)

A

-difference between HL and the output of a 2cc coupler

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6
Q

Real ear coupler difference (RECD)

A

-difference between the 2cc coupler and the dB SPL of the ear canal
-childrens will be larger

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7
Q

How to measure RECD?

A
  1. calibrate the RECD transducer
  2. on verifit, select the coupling that will be used for the on-ear RECD measurement: either foam tip or earmold
  3. position patient in front of verifit and place probe tube
  4. attach RECD transducer to foam tip or earmold and place in ear canal over the probe tube
  5. measure the RECD/WRECD
  6. adjust gain in manufacturer software to meet prescriptive targets
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8
Q

DSL

A

-restoration of normal loudness perception will create better acceptance by the listener
-goal is to amplify speech sounds so that normal inter-frequency loudness relations are maintained
-low frequency vowels will get more loudness weight than high frequency consonants

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9
Q

NAL

A

-equalized loudness across frequency bands results in higher intelligibility
-only making frequencies louder that need it
-goal is to amplify speech sounds so that they are perceived as equally loud

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10
Q

LTASS

A

long term average speech spectrum (the lines inside the green shaded area)

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11
Q

MPO

A

-maximum power output
-remember to mute the other ear thats not being tested

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12
Q

Overview of a proper fitting

A
  1. calibrate verification system
  2. otoscopy and probe mic placement
  3. measure RECD
  4. hearing aid placed over probe mic
  5. select prescriptive formula/rationale on verification system
  6. run specific types of stimuli and record what the hearing aid is doing in the ear
  7. adjust gain in the manufacturer software
  8. re-run stimuli and keep adjusting until targets are met
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13
Q

When do you repeat REM after the initial fitting?

A

-change in acoustic coupling
-change in hearing
-unable to resolve patient complaint

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14
Q

How does the loop system work with telecoils?

A

loop creates a magnetic field and the HA can connect when in that program

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15
Q

What does near-field connectivity mean?

A

-HA to HA
-how the aids talk to each other
-share spatial/noise information

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16
Q

What is far-field connectivity?

A

-HA to other devices like phones and accessories

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17
Q

International Telecommunication Union (ITU)

A

-established 1865
-under the UN now, it creates global technical standards
-divides the world into 5 regions with set frequency allocations

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18
Q

What are the three primary types of wireless protocol?

A

-NFMI (near-field magnetic induction)
-2.4GHz (used for almost all phones)
-900MHz (obsolete at this point, Starkey created it)

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19
Q

NFMI

A

-Siemens introduced this in 2004
-allowed for ear to ear ear level control co-ordination (volume, program) for the first time
-short-range wireless transmission using magnetic induction
-can go through and around objects
-magnetic field is generated on a carrier frequency and digitally modulated. receiver demodulates the signal
-capable of carrying audio and data signals
-transmission rates can vary; each mfg uses a proprietary NFMI signal to perform different actions
-distance usually width of the head
-uses induction where the coils interact
-if take out HA to change programming, will only change that HA (not in range)
-low energy- does not take much from the battery
-each manufacturer has own NFMI and usually changes chip to chip
-the signal degrades quickly and within a meter
-may experience interference with other magnetic sources
-cannot receive outside audio source directly due to short range
-not powerful enough for things like TV, needs intermediary device
-no audio delays

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20
Q

2.4 GHz

A

-far-field transmission- propagates easily through the air with good signal strength
-lots of tech operating in this frequency region
-transmission distance is much further than NFMI
-uses more power
-does not propagate through the human head or around it due to high frequency and short wavelength. this makes HA to HA communication not as easy
-2.4GHz is getting crowded

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21
Q

900 MHz RF

A

-far-field transmission (and near-field)
-in between the 2.4 GHz and NFMI ranges, 900 MHz RF wavelength
-although not approved for sale in other countries, it is not typically a problem for a HA wearer to travel to these countries with their wireless tech
-used by Starkey

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22
Q

Other considerations for wireless signal processing?

A

-bit rate: if low may only perform basic signal processing but if high may have more complex features
-data exchange: unidirectional (one way transmission of info) or bidirectional (two-way transmission)

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23
Q

Unidrectional data exchange

A

One way transmission of information
-have to hold phone to mouth so listener can hear you
-older iPhones, many MFi models

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24
Q

Bidirectional data exchange

A

two-way transmission
-hearing aids can transmit speakers voice to the phone

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25
Q

What is the speed of transmission most impacted by?

A

processing capability/size of the computer chips1

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26
Q

What are the 5 types of Bluetooth?

A

-MFi (made for iPhone)
-Bluetooth LE
-Bluetooth Classic
-Bluetooth 5.0
-Coming soon is Bluetooth LE-Audio

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27
Q

MFi

A

uses Apple patented technology for audio transmission from the phone
only paired to one device at a time
one way phone call until recently

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28
Q

Bluetooth LE

A

low energy used for transmitting data (wireless programming of HA, app control), not audio

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29
Q

Bluetooth Classic

A

available on every Bluetooth audio device for streaming bidirectional phone calls

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30
Q

Bluetooth 5.0

A

allows streaming from two different devices at once (2 headphones) and 4x the range of older bluetooth

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31
Q

Bluetooth LE-Audio

A

low power consumption, less latency

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32
Q

ASHA

A

-audio streaming for hearing aids (2019)
-introduced by google for android systems
-two way (hands free) phone streaming
-hearing aids previously MFi only, now compatible with androids

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33
Q

Auracast

A

-may allow for true public broadcasting to nay number of compatible hearing devices

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34
Q

Do HAs use more or less energy than a phone?

A

less

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35
Q

Starkey Genesis AI

A

-healthable
-integrated sensors and AI
-thrive mobile app with “Edge Mode”
-real-time language translation
-dual -radio wireless platform

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36
Q

Phonak Lumity

A

-uses bluetooth classic to connect to any device
-master HA connects to phone via bluetooth and then uses NMFI to other aid
-RogerDirect- no more audioshoes or receivers
-unitron vivant is the same

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37
Q

Sonova SWORD chip

A

-Sonova Wireless One Radio Digital (SWORD) launched with the original Audeo Direct B model
-2.4 GHz radio chip with low power consumption
-first to be universal
-proprietary audio links for ear-to -ear streaming and binaural audio streaming using bluetooth classic

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38
Q

What does bimodal streaming mean?

A

CI and HA working together

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39
Q

What HAs pair up with Cochlear

A

resound

40
Q

What HAs pair up with AB

A

phonak

41
Q

What do we learn from EAA

A

-output parameters of the HAs
-does not tell us how well its programmed
-is the HA working per ANSI standards
-frequency response
-distortion
-EIN

42
Q

Directional mic testing

A

-measures the SNR between the front and rear mics
-can help to confirm that the directional mics are working and how much separation is created in the presence of noise

43
Q

Directional mic couplers

A

Verifit 1
-same positioning and same couplers used
-EAA and DM use the silver couplers with the HAs over the x
Verifit 2
-different positioning and different couplers than what was used in EAA
-EAA- blue coupler, HA over the X
-DM- silver, coupler binaural (can run both hearing aids at once), mic over the X

44
Q

Directional mic positioning Verifit 2

A

-front mic facing forward, rear mic facing back (toward the opening of the test box lid)
-BTE and RIC can use a stand

45
Q

DM testing

A

-top solid line represents HA mic closest to the front test box speaker
-lighter line represents HA mic closest to rear test box speaker
-separation demonstrates how rear mic has reduced output in the presence of noise

46
Q

Why have a separate DM test

A

-only DM testing in a test box will tell you if they are providing SNR benefit
-very difficult to hear DM problems with a stethoset
-EAA and REM will not detect a problem between mics (it will catch overall output of the HA and possible weakness of the front mic. the back mic could be dead and EAA and REM may miss it)

47
Q

DM considerations

A

-reversed microphones have become significantly less common with advances in HA fabrication and automation-mics do sustain damage over time and become less sensitive
-the separation between the mics can lessen over time, providing less benefit to the patient
-valuable to retest EAA and DM every 3 years
-poor DMs may be contributing to patients difficulty in background noise

48
Q

What is considered a “pass” for DM?

A

-there is no standard, need to use clinical judgement as to what looks reasonable
-some manufacturers demonstrate more mic separation in the test box than others
-minimal to no separation is a fall
-helpful to compare DM separation over time (should stay the same)

49
Q

How does telecoil position matter

A

-to get the strongest response, coil needs to be perpendicular to the loop but this is different for the phone
-many HAs will have the telecoil on its side to try and split the difference

50
Q

How do you test a telecoil

A

-listening check with stethoset can test whether transmission is occurring but difficult to test in situ
-test in test box

51
Q

Telephone magnetic field simulator (TMFS)

A

coil placed under test surface intended to simulate a telephone handset

52
Q

SPL for inductive telephone simulator (SPLITS)

A

coupler SPL when the input is the magnetic field generated by the TMFS

53
Q

HFA-SPLITS

A

average of the SPLITS curve at HFA frequencies

54
Q

Relative simulated equivalent telephone sensitivity (RSETS)

A

HFA SPLITS minus (RTG + 60)
-a positive number indicates greater output when using the telecoil than when using the microphone
-a negative number indicates lesser output when using the telecoil than when using the mic

55
Q

Verifit 1 phone telecoil test

A

-EAA needs to be run first
-put HA into telecoil only setting (in mfr software or push button)
-select “telecoil” under audioscan test options
-start TMFS test- telephone magnetic field simulation
-position HA flat over the T
-press continue
-move the HA around the chamber surface to maximize the AVG-SPLITS value
-once you have the highest value, press continue to run the SPLITS curve
-AN RSETS value will generate if ANSI was run first

56
Q

What does a negative TMFS value mean

A

Weak phone response

57
Q

SPL in a vertical magnetic field (SPLIV)

A

coupler SPL when the HA is positioned as worn in a vertical magnetic field

58
Q

HFA-SPLIV

A

AVG of the SPLIV curve at the HFA frequencies

59
Q

Relative test loop sensitivities (RTLS)

A

-HFA SPLIV minus (RTG +
60)
-positive value indicates greater output when listening in a room loop than when using the mic
-negative value indicates lesser output when listening in a room loop than when using the mic

60
Q

Verifit 1 loop t-coil test

A

-run full EAA test
-put HA into telecoil only setting (in mfr software or push button)
-select telecoil under audioscan test options
-start test loop test
-position HA upright over the T
-press continue and keep HA still. the SPLIV line will run and generate an average SPLIV value
-an RTLS value will generate if ANSI was run first

61
Q

Test loop results

A

-when the RTLS is less than the mic output, patient may report that the loop phone program is too weak and this may also indicate the coil is in a vertical position

62
Q

Verifit 2 phone t-coil test

A

-run full EAA test
-put HA into telecoil only setting
-select telecoil under audioscan test options
-start TMFS test (telephone magnetic field simulation)
-position HA flat over the T on the tele-set (lower left of chamber)
-move the HA around the teleset to maximize the AVG-SPLITS value
-once you have the highest value, press the check to run the SPLITS curve then keep the HA still
-an RSETS value will generate if ANSI was run first

63
Q

What is the RSETS value

A

-how does it compare the mic output
-want it close to 1- shows a great response

64
Q

Verifit 2 loop telecoil test

A

-there is an embedded induction loop around the light grey floor of the test chamber for loop testing
-run full EAA
-put HA into telecoil only
-select telecoil under audioscan test options
-start test loop test
-position HA upright over the X
-press the check and keep HA still, the SPLIV line will run and generate an average SPLIV value
-an RTLS value will generate if ANSI was run first

65
Q

What is the RTLS value

A

-how does it compare to the mic output
-how do the RSETS and RTLS compare to each other

66
Q

Why do we use REM to test phone t-coil

A

-when the tele-set is placed against the ear, it mimics the placement of a phone, providing a more realistic in situ measurement compared to test box
-can verify binaural streaming (duophone)
-can use monitor headphones for clinician
-only availble with verifit 2

67
Q

REM and phone t-coil verification

A

-fit HA to prescriptive targets
-run 65 dB curve as test 1
-add telecoil or auto-t program
-for curve 2, select tele-test 65 under the level drop down menu
-hold tele-test handset against the HA (like holding a cellphone)
-click record
-adjust gain and frequency response of t-coil program in manufacturer software so that curve 1 and curve 2 match

68
Q

Clinical application of t-coil testing

A

-patient complains that phone telecoil program is not working or not very helpful — check user error (placement of phone, is the program automatic or manual)
–could not hear well in looped room — check user error (successfully switching into manual program and out of it, was the room looped, was the presenter speaking into the mic)
-abnormal buzzing or distortion in t-coil program — t-coils can break or be poo quality, may be near another electric source that may be interfering

69
Q

Distortion

A

-EAA includes 3 frequencies of harmonic distortion
-there is no ANSI standard but the HCC uses under 10%
-uses silver coupler

70
Q

What type of HAs can a battery drain test not be done?

A

rechargeable

71
Q

What are the possible causes for battery drain

A

-bad pack of batteries
-mercury free- need more time once sticker is removed
-moisture
-increased streaming or exposure to noise

72
Q

Digital sound processing (DSP)

A

how the hearing aid converts acoustic sound into digitized codes, which then can be processed to improve the speech signal

73
Q

Sampling rate

A

Number of times per second that the hearing aid analyzes incoming sound at regular intervals

74
Q

What are examples of DSP

A

-noise reduction
-wind reduction
-feedback suppression
-frequency lowering
-advanced directionality of mics
-binaural synchronization between aids
-audio streaming/bluetooth

75
Q

What is the goal of noise reduction

A

-only amplify things you want to hear and reduce the things you do not
-NR separates the parts to try to decipher what you want to hear

76
Q

Why can’t hearing aids work as well as noise-cancelling headphones

A

not the same goal- the headphones know what you want to hear compared to what you do not; the HAs have top let sound in while cancelling out

77
Q

Are DSP features less effective with open and closed fittings? Why?

A

Open because it cannot process what is not being amplified and it is harder to block what is free to pass right into the ear

78
Q

Is noise or speech modulated?

A

Speech

79
Q

Three parts of modulation of speech

A
  1. modulation rate
  2. comodulation/synchrony detection (same modulation rate visible across multiple channels
  3. modulation depth (estimation of SNR in each channel)
80
Q

Modulation rate of speech

A

-can be visualized by using a spectrogram (opening and closing mouth while talking is modulation)
-main method of detecting speech
-rate is usually 3-6 Hz which is about the rate of syllabic production
-rate is the outcome of the higher amplitude vowels interspersed with the weaker consonants and pauses of speech

81
Q

Does noise or speech have a faster modulation

A

Noise

82
Q

Comodulation

A

-when a repeatable modulation rate is seen across several frequency channels
-because human vocal cords resonate in this limited way, speech becomes more predictable than other types of sounds/noise
-we speak at multiple frequencies so modulation rate will show up at multiple frequency rates (not noise)

83
Q

Modulation depth

A

-can estimate modulation depth within each signal processing channel
-maxima and minima of the envelope are calculated to figure out the modulation depth
-an estimate of SNR in that channel can be made (difference between average speech level and average noise level)
-works well if it is speech vs. continuous noise in a narrow frequency region
-also assumed that the desirable signal is speech

84
Q

NR strategies

A

-decrease low frequency gain or raise TK (noise more likely to be low pitch, remove impact of upward spread of masking, expansion for quieter levels of noise)
-Wiener filtering- alter gain at each frequency, depending on the SNR at that frequency (will only alter if it thinks there is noise in that spot; HA in a higher tier can do it more discreetly since there is more channels; gain is reduced as the SNR worsens)

85
Q

How is the Wiener filter typically deployed? What issue is it trying to overcome?

A

Typically deployed with the use of a short-term Wiener filter in combination with a speech detector to overcome the issue that an assumption is we know what the power of the signal compared to the power of the signal plus noise and that the values of both are stable

86
Q

Spectral subtraction

A

-the magnitude of the noise spectrum is subtracted from the magnitude of the speech spectrum
-this is a broad-spectrum reduction across many frequencies (this is difference from the Wiener filter)
-speech quality will be affected where the speech and noise overlap (which may degrade the signal), but may still be preferable to the discomfort of noise
-most useful for unchanging, stationary noise

87
Q

Comb filter

A

-the negative side effect of sound filtering and delays
-makes speech sound distorted and unnatural

88
Q

Dynamic Noise Cancellation (Phonak)

A

-spatial noise cancellation that words with directional beamforming

89
Q

Sound relax (Phonak)

A

softens sudden loud sounds

90
Q

Noiseblock (Phonak)

A

Wiener filter, estimates short term SNR estimate in each channel

91
Q

Soft Noise Reduction (Phonak)

A
  • TKs, how the HA amplify the soft sounds like come in
92
Q

NR and listening

A

-does not improve speech perception in noise
-hearing aid wearers prefer to have NR on
-improved sound quality with NR
-better listening in comfort with NR

93
Q

Verification of NR for the verifit 1

A

-place instrument into the box, coupled and positioned as required for EAA
-with NR off, run test 1 with 70 dB selected noise (AC, vacuum, bus ride)
-with NR on, run test 2 with 70dB with same selected noise)
-make sure to stimulate instrument for a minimum of 10-15 seconds before capturing curves

94
Q

Verification of NR with verifit 2 REM

A

-place probe tubes appropriately
-insert HA
-position the patient appropriately in front of the verifit
-test, on ear, NR
-test captures a thick curve before the NR kicks in
-the later, thin, curve shows a comparison after it kicks in
-patient and clinician can watch the HA react in real time
-compare response with and without noise reduction on for the given stimulus
-several stimuli (AC, bus, vacuum)

95
Q
A

Fitting and Dispensing (2 decks)

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