Diagnostics of the cochlear amplifier by means of distortion product otoacoustic emissions [Elektronische Ressource] / Jörg Alexander Müller

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Diagnostics of the cochlear amplifier bymeans of distortion product otoacousticemissionsJ¨org Alexander Mull¨ erLehrstuhl fu¨r Hals-Nasen-Ohrenheilkunde fu¨r Realzeit-ComputersystemeDiagnostics of the cochlear amplifier by means ofdistortion product otoacoustic emissionsJo¨rg Alexander Mu¨llerVollst¨andiger Abdruck der von der Fakult¨at fu¨r Elektrotechnik und Informationstechnik derTechnischen Universit¨at Mun¨ chen zur Erlangung des akademischen Grades einesDoktors der Ingenieurwissenschaften (Dr.-Ing.)genehmigten Dissertation.Vorsitzender: Univ.-Prof. Dr.-Ing. K. DiepoldPru¨fer der Dissertation: 1. apl. Prof. Dr.-Ing., Dr.med.habil. Th. Janssen2. Univ.-Prof. Dr.-Ing. G. F¨arberDie Dissertation wurde am 20.02.2008 bei der Technischen Universit¨at Mu¨nchen eingereichtund durch die Fakult¨at fu¨r Elektrotechnik und Informationstechnik am 06.06.2008 angenom-men.AcknowledgementsThisdissertationevolvedasaresultfrommyworkasacademicassistantatthelaboratoryof experimental audiology at the ear, nose and throat clinic at Klinikum rechts der Isar,Technische Universit¨at Munc¨ hen.

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Diagnostics of the cochlear amplifier by
means of distortion product otoacoustic
emissions
J¨org Alexander Mull¨ erLehrstuhl fu¨r Hals-Nasen-Ohrenheilkunde fu¨r Realzeit-Computersysteme
Diagnostics of the cochlear amplifier by means of
distortion product otoacoustic emissions
Jo¨rg Alexander Mu¨ller
Vollst¨andiger Abdruck der von der Fakult¨at fu¨r Elektrotechnik und Informationstechnik der
Technischen Universit¨at Mun¨ chen zur Erlangung des akademischen Grades eines
Doktors der Ingenieurwissenschaften (Dr.-Ing.)
genehmigten Dissertation.
Vorsitzender: Univ.-Prof. Dr.-Ing. K. Diepold
Pru¨fer der Dissertation: 1. apl. Prof. Dr.-Ing., Dr.med.habil. Th. Janssen
2. Univ.-Prof. Dr.-Ing. G. F¨arber
Die Dissertation wurde am 20.02.2008 bei der Technischen Universit¨at Mu¨nchen eingereicht
und durch die Fakult¨at fu¨r Elektrotechnik und Informationstechnik am 06.06.2008 angenom-
men.Acknowledgements
Thisdissertationevolvedasaresultfrommyworkasacademicassistantatthelaboratory
of experimental audiology at the ear, nose and throat clinic at Klinikum rechts der Isar,
Technische Universit¨at Munc¨ hen. The foundation for a large part of the results was my
collaborationinthefollowingprojects,whichwerefundedbyDeutscheForschungsgemein-
schaft (DFG): ”Entwicklung objektiver Anpassparameter fur¨ mehrkanalige Dynamikkom-
pressionsh¨orger¨ate mittels DPOAE und FAEP” (Ja597/6), ”Fruher¨ kennung der individu-
ellen Lar¨ mvulnerabilit¨at des Ohres durch Messung des olivocochle¨aren Reflexes” (Ja597/7
and Wa1677/2) and ”Quantifizierung und Differenzierung sensorineuraler H¨orst¨orun-
gen mittels Distorsionsprodukten Otoakustischer Emissionen (DPOAE) und Auditorischer
Steady State Antworten (ASSR)” (Ja597/9).
I am particularly indebted to Prof. Dr. Dr. Thomas Janssen who made it possible for me
to work on these interesting projects and who inspired me persistently for the scientific
field of audiology. The scientific framework and the work environment he provided was
excellent. Furthermore,IamgratefultoProf. Dr. GeorgF¨arberforagreeingtoreviewthis
dissertationdespiteitsslightlyunusualtopic. AspecialthanksisduetoDr. HansOswald
who started everything. Beyond that, I would like to thank all persons who participated
in the various studies and who had a tremendous share in the successful realization of the
experiments, i.e. Dr. Wolfgang Wagner from Eberhard-Karls-Universit¨at Tubingen¨ who
initiated the study about noise vulnerability and his co-worker Guido Heppelmann, Dr.
Daniel Gehr who put a lot of work in the organization of the neonate measurements, and
Dr. WolframWeinsheimerwhomadeitpossibletorealizethenoiseexposureexperiments
at Voith AG. Moreover, I thank all the hard-working medical students, who helped in
conducting and organizing the often time-consuming measurements, i.e. Annette Klein,
Susanne Dietrich, Zehra Akkaya, Julia Weinsheimer, and Anemone Luca. Also, I am
grateful to all my colleagues at the laboratory of experimental audiology at Klinikum
rechts der Isar for discussion and helpful input to my work and for a smile once in a while
whichmadeeverythingmucheasier. Particularly,IwouldliketothankThomasRosnerfor
hisfriendshipandforthevaluableandinspiringdiscussionswhiledoingovertime. Beyond
that, I thank Florian Kandzia, Frank B¨ohnke, Maximilian Hoffmann von Waldau, and
AnnaRut¨ tenauerforpleasanthoursintheuniversitycafeteria. Lastbutnotleast,Ithank
my friends and my family who continuously supported me and who helped me in seeing
through good and hard times along my way from the first beginning until bringing this
work to an end. I sincerely thank you very much!
Munich, February 2008Contents
List of Symbols viii
1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Outline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Principles of hearing and hearing testing 5
2.1 Physics and psychoacoustics . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Physiology and pathophysiology . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Pure-tone audiometry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3.1 Hearing threshold determination . . . . . . . . . . . . . . . . . . . . 18
2.3.2 Determination of loudness perception . . . . . . . . . . . . . . . . . 20
2.3.3 General problems using psychoacoustic measurement procedures . . 23
2.4 Impedance audiometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.4.1 Tympano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.4.2 Stapedius reflex measurement . . . . . . . . . . . . . . . . . . . . . 25
2.5 Otoacoustic emissions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.5.1 Classification of otoacoustic emissions . . . . . . . . . . . . . . . . . 26
2.5.2 Generation mechanism of distortion product otoacoustic emissions
(DPOAEs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5.3 Evaluation and clinical applications of DPOAEs . . . . . . . . . . . 31
3 Instrumentation and methods 37
3.1 Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.2 Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.3 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.3.1 Hearing threshold determination . . . . . . . . . . . . . . . . . . . . 41
3.3.2 Categorical loudness scaling (CLS) . . . . . . . . . . . . . . . . . . 43
3.3.3 Distortion product otoacoustic emissions (DPOAEs). . . . . . . . . 44
3.4 Stimulus calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4 Implications for objective hearing aid fitting by means of DPOAEs 52
4.1 Material and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.1.1 Subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.1.2 Stimulus generation . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
vContents
4.1.3 DPOAE measurement procedure . . . . . . . . . . . . . . . . . . . 54
4.1.4 CLS measurement procedure . . . . . . . . . . . . . . . . . . . . . . 55
4.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.2.1 Normative data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.2.2 Hearing loss case examples . . . . . . . . . . . . . . . . . . . . . . . 59
4.2.3 Comparison of DPOAE and CLS I/O and gain functions for pooled
data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5 Differentiation between middle ear and cochlear hearing loss by means of
DPOAEs 69
5.1 Material and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.1.1 Subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.1.2 Stimulus generation and DPOAE measurement procedure . . . . . 70
5.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.2.1 DPOAE test performance . . . . . . . . . . . . . . . . . . . . . . . 71
5.2.2 DPOAE grams and DPOAE I/O functions in neonates, normal
hearing subjects, and cochlear hearing loss patients . . . . . . . . . 72
5.2.3 DPOAE threshold and compression estimates - normal hearing ver-
sus neonatal hearing and cochlear hearing loss . . . . . . . . . . . . 74
5.2.4 Modeling DPOAE I/O functions in sound conductive and cochlear
hearing loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.2.5 Frequency-specific DPOAE behavior in neonates . . . . . . . . . . . 79
5.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6 Improvements in quantifying efferent reflex strength by means of DPOAEs 87
6.1 Material and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.1.1 Subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.1.2 Stimulus generation and DPOAE recording . . . . . . . . . . . . . . 88
6.1.3 DPOAE fine structure measurement procedure . . . . . . . . . . . . 88
6.1.4 CAS DPOAE measurement procedure . . . . . . . . . . . . . . . . 89
6.1.5 Ipsilateral DPOAE adaptation measurement procedure . . . . . . . 90
6.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.2.1 DPOAE fine structure and its intra-individual reproducibility and
inter-individual distribution . . . . . . . . . . . . . . . . . . . . . . 91
6.2.2 Effect of CAS on DPOAEs and its intra-individual reproducibility
and inter-individual distribution . . . . . . . . . . . . . . . . . . . . 93
6.2.3 IpsilateralDPOAEadaptationanditsintlreproducibil-
ity and inter-individual distribution . . . . . . . . . . . . . . . . . . 97
6.2.4 Correlation between DPOAE measures . . . . . . . . . . . . . . . . 100
6.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7 Further efforts to predict individual vulnerability to noise overexposure 105
7.1 Material and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
7.1.1 Subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
viContents
7.1.2 Noise exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.1.3 Pure-tone threshold measurement procedure . . . . . . . . . . . . . 110
7.1.4 Stimulus generation and DPOAE recording . . . . . . . . . . . . . . 110
7.1.5 DPOAE fine structure measurement procedure . . . . . . . . . . . . 111
7.1.6 CAS DPOAE measurement procedure . . . . . . . . . . . . . . . . 114
7.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
7.2.1 Impact of noise exposure on pure-tone threshold data . . . . . . . . 115
7.2.2 Impact of noise exposure on DPOAE fine structure data . . . . . . 118
7.2.3 Relationship between pure-tone threshold and DPOAE fine struc-
ture before and after noise exposure . . . . . . . . . . . . . . . . . . 122
7.2.4 CAS DPOAE data . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.2.5 Relationship between CAS DPOAE, pure-tone threshold, and
DPOAE fine structure . . . . . . . . . . . . . . . . . . . . . . . . . 130
7.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
8 Further efforts to determine the causes for age-related hearing loss 142
8.1 Material and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
8.1.1 Subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
8.1.2 Audiometric tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
8.1.3 Pure-tone threshold fine structure measurement procedure . . . . . 144
8.1.4 Stimulus generation and DPOAE recording . . . . . . . . . . . . . . 145
8.1.5 DPOAE fine structure measurement procedure . . . . . . . . . . . . 146
8.1.6 CAS DPOAE measurement procedure . . . . . . . . . . . . . . . . 146
8.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
8.2.1 Audiometric threshold data . . . . . . . . . . . . . . . . . . . . . . 147
8.2.2 Tympanometry data . . . . . . . . . . . . . . . . . . . . . . . . . . 149
8.2.3 Pure-tone threshold fine structure data . . . . . . . . . . . . . . . . 149
8.2.4 DPOAE fine structure data . . . . . . . . . . . . . . . . . . . . . . 150
8.2.5 CAS DPOAE data . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
8.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
9 Conclusions and outlook 165
Bibliography 169
viiList of Symbols
A/D Analog-to-digital
ALU Arithmetic logic unit
AN Auditory nerve
API Application programming interface
c Sound velocity [m/s]
CA Cochlear amplifier
CAS Contralateral acoustic stimulation
CLS Categorical loudness scaling
CN Cochlear nucleus
Codec Coder/Decoder
CU Categorical unit
D/A Digital-to-analog
dB Decibel
DFG Deutsche Forschungsgemeinschaft
DLL Dynamically linked library
DMA Dynamic memory access
DPOAE Distortion product otoacoustic emission
DRAM Dynamic RAM
DSP Digital signal processor
eCL Estimated compression loss
eHL hearing loss
ECV Ear canal equivalent volume
φ Phase
f Frequency [Hz]
FFT Fast Fourier Transformation
GUI Graphical user interface
HL Hearing level
IAS Ipsilateral acoustic stimulation
IHC Inner hair cell
I/O Input/Output
IVN Inferior vestibular nerve
k Compression of I/O function (= 1/slope)
λ Wave length [m]
l Length [m]
viii