The Hearing Sciences

Description

Covers all the topics required for a thorough understanding of hearing sciences: acoustics, anatomy and physiology of the auditory and vestibular systems, psychoacoustics, and basic instrumentation. Written in a straightforward style, this text is appropriate for undergraduate students. Fundamental concepts from earlier chapters are reinforced as more complex topics are introduced. In short, it is an accessible book that students will rely on throughout their academic careers. Instructors may find the more advanced chapters useful as supplementary material in AuD programs.

Table of contents

· Preface
· Acknowledgments and Dedication
· About the Authors

Section One: Basic Acoustics and Instrumentation

· Chapter 1. Physical Properties of Sound
Energy
Opposing Forces
Units of Measurement
Sound Energy
Compression and Rarefaction
Frequency
Intensity
Limits of Human Frequency Detection
Summary

· Chapter 2. Ratios, Logarithms, and Decibels
Ratios
Exponents
Positive Exponents
Negative Exponents
Zero Exponent
Laws of Exponents
Addition
Subtraction
Multiplication, Division, and Exponents of Exponents
Scientific Notation
Adding and Subtracting Numbers in Scientific Notation
Logarithms Are Based on Exponents
Logarithms of Numbers with Only 1 and 0
Logarithms of Numbers Other Than 1 and 0
Why Are Logs Important?
Antilogs
The Log of X Times Y
Log of (X Divided by Y)
Hints on Using the Calculator
Obtaining the Log of a Number That Is Raised to a Power
The Decibel
Power
Doubling Power
Pressure
Doubling Power Does Not Double Pressure
Doubling the Distance from the Source
Practice at Calculating Sound Pressure Levels
Practice at Calculating Intensity Levels
Relative Powers and Pressures
Adding Decibels
Summary

· Chapter 3. Further Examination of Properties of Sound
Speed of Sound Transmission
Wavelength
Period
Relationship of Period and Wavelength
Sound Transmission Effects
Diffraction and Reflection
Sound Absorption, Transmission Loss, and Reverberation Time
Sound Propogation Through Holes
The Doppler Effect
Sonic Booms and Thunder
Air Density Affects Wavelength
Types of Decibel Scales
Review of dB SPL and dB IL
dB Increase
dB HL and SL
Introduction to the Audiogram
Summary

· Chapter 4. The Sine in Sine Waves and Other Types of Sound Waves
Triangles and Sines
Plotting Sine Waves
Simple Harmonic Motion, the Pendulum and the Circle
Molecular Vibration and the Sine Wave
How We Calculate Relative Amplitude When Phase Is Known
How We Calculate Phase When Time and Frequency Are Known
Complex Sound
Summing Pure Tones That Differ Only in Phase or Amplitude
Summing Pure Tones That Differ in Frequency
Harmonics and Distortion
Air Molecule Vibration Pattern for Complex Sounds
Fourier’s Theoum
Common Types of Tones and Noise
The Click (Transient) Signal
Summary
Answers to Chapter Problems

· Chapter 5. Impedance, Energy Transfer, and Resonance
Impedance
Impedance of a Medium
Energy Transfer
Resonance of Systems
Standing Waves and Resonances of Tubes
Standing Waves
Resonances of a Tube Closed at One End
Resonances of a Tube Closed at Both Ends
Summary

· Chapter 6. Electricity and Analog Systems
Electron Flow
Ohm’s Law
Electrical Circuits
Ionic Flow
Common Analog Components
Microphones
Amplifiers
Filters
Calculating Filter Cutoff Frequencies
Cutoff Frequencies Defined at 3-dB
Down Points
Speakers
Transducers
Volume Controls
Frequency Response Controls
Summary

· Chapter 7. Digital Systems and Digital Signal Processing
Bits and Sampling Rates
How Big Is That?
How Often Should Amplitude Be Measured?
Building an Analogy to Use Later
Additional Digitization Concepts
Analog to Digital Converters
Nyquist Frequency
Aliasing
Antialiasing Filtering
Digital to Analog Converters
Imaging
Anti-Imaging Filters
Overview of What a Digital System Can Do
Fast Fourier Transform Analysis of Auditory Signals
Windowing
Overlapping Windows
Goal of FFT Analysis
FFT Resolution
Example FFT Results
Digital Noise in the FFT Analysis
Calculating Noise per Bin and dB of Bandwidth per Bin
Clinical Correlate: Bins in Audiology
Time Domain Signal Averaging
Clinical Correlate: Digital Hearing Aids
Summary

· Chapter 8. Some Equipment Used in Audiology and Hearing Science
Audiometers
Signal Generators
Sound Booths
Immittance Devices (Middle Ear Analyzers)
Tympanometers
Acoustic Stapedial Reflex Measurement
Otoacoustic Emissions Devices
Spontaneous Otoacoustic Emission Measurement
Transient-Evoked Otoacoustic Emissions Measurement
Distortion-Product Otoacoustic Emissions Measurement
Signal Processing Used in Analysis of All
Types of OAE Measurements
Auditory Evoked Response Measurement Systems
Common Mode Rejection
Time-Domain Signal Averaging and Artifact Rejection
Filtering the Evoked Response
Hearing Aid Analyzers
Real-Ear Measurement Systems
Speech Mapping Technology
Traditional Real-Ear Testing
Power Supplies for Hearing Instruments and
Testing Equipment: Safety Concerns and Electronic Noise
Relative Safety of AC and DC Power Supplies
What Is AC Electricity?
Ground Noise
Grounding Equipment, Fuses, and Circuit Protectors
Floor Noise
Microphones
Types of Microphones
Microphone Directionality
Microphone Care
Sound Level Meters
Calibration
Types of Decibel Scales
Sound Level Meter Response Times
Decibel Range Selection
Earphone Couplers
Frequency Counters
Audiometer Calibrators
Oscilloscopes
Summary

Section Two: Introduction to Speech Acoustics

· Chapter 9. Classification of Speech Sounds
Consonants, Vowels, and Diphthongs
Consonants Are Categorized by Place of
Articulation, Manner of Articulation, and Voicing
Alveolar Sounds
Palatal Sounds
Glottal Sound
Velar Sounds
Linguadental Sounds
Bilabial Sounds
Labiodental Sounds
Clinical Correlate: The Limits of Lip Reading
Vowels Differ in Tongue Height, Placement, Tension and Lip Rounding
Front Vowels
Central Vowels
Back Vowels
Summary

· Chapter 10. Acoustics of Speech
How Speech Sound Waveforms Can Be Viewed
Fundamental Frequency, Harmonics, and Formant Frequencies
Acoustic Characteristics of Vowels
Formant Frequencies Are Created by Resonance of the Vocal Tract
F1 and F2 of Vowels
Intensity of Vowel Sounds
Low Importance of Vowels for Speech Understanding
Acoustic Characteristics of Consonants
Stop Consonant Burst Energy Is Wideband
Voice Onset Time Distinguishes Voiced and Unvoiced Sounds
Formant Frequency Transitions Provide Additional Acoustic Cues
Fricatives Have Longer Duration and High-Frequency Energy
Affricatives Have Characteristics of Both Plosives and Fricatives
Nasals Have Low-Frequency Energy, Nasal Murmur, and Antiresonances
Glides Are Characterized by Vowel Formant Transitions
Intensity of Consonants
Importance of Consonants for Speech Understanding
Clinical Correlate: Shouting Doesn’t Help Most Hearing Impaired
Summary

Section Three: Anatomy and Ph ysiology of the Ear

· Chapter 11. Overview of Anatomy and Physiology of the Ear
Anatomic Terms for Location
Anatomic Views
General Sections of the Ear
Clinical Correlate: Types of Loss
The Temporal Bone
Overview of Physiology
Summary

· Chapter 12. Introduction to the Conductive Mechanisms
The External Ear
The Middle Ear
The Tympanic Membrane
Medial Wall Landmarks
Posterior Wall Landmarks
The Ossicles
Overview of How Middle Ear Ossicular Motion Permits Hearing
Middle Ear Muscles
The Eustachian Tube
Summary

· Chapter 13. Introduction to the Physiology of the Middle Ear
Resonances of the External Ear
Energy Transfer Through the Middle Ear
Impedance Mismatch Between Air and Cochlear Fluids
The Middle Ear as an Impedance-Matching Transformer
Ossicular Lever
Areal Ratio
The Acoustic Reflex
Summary

· Chapter 14. Bone Conduction Hearing
Bone Conduction Mechanisms
Skull Vibration
Intertial Aspects of Bone Conduction
Compressional Aspects of Bone Conduction
Hearing Is Tested by Air- and Bone-Conduction
Bone-Conduction by Air-Conduction and the Occlusion Effect
Clinical Correlate: Diagnosing Conductive
Hearing Loss
Summary

· Chapter 15. Advanced Conductive Anatomy and Physiology
Pinna
Embryologic development
Landmarks
Clinical Correlate: Defects of the Outer Ear May Signal
Middle and Inner Ear Defects
Physiology of the Pinna
External Auditory Meatus
Detailed Anatomy
Clinical Correlate: Otoscopy and Earmold Impressions
Proximity to the Temporomandibular Joint
Clinical Correlates: Temporomandibular Joint Pain and the Effect of TMJ Movement on Earmold Impressions
Proximity of Nerves to the External Auditory Meatus
Skin of the External Auditory Meatus
Cerumen
Clinical Correlate: Cerumen Management
Detailed Physiology of the External Auditory Meatus
Clinical Correlate: Real Ear Measurement
Tympanic Membrane
Slant and Cone Depth
Clinical Correlate: Cone of Light
Detailed Study of the Ossicular Chain
Resonance of the Middle Ear
Mass and Stiffness of the Middle Ear
Affect Sound Transmission Differently at Different Frequencies
Clinical Correlate: Carhart’s Notch
Transmission of Sound Through the Tympanic Membrane Is Affected by Mass and Stiffness
Clinical Correlate: Measuring Middle Ear Resonance
Clinical Correlate: Measuring Middle Ear Pressure
Acoustic Reflex Physiology
Reflex Latency
Clinical Correlate: Measuring Acoustic Reflex
Reflex Adaptation
Reflex Threshold
Clinical Correlate: Measuring Acoustic Reflex Decay
Clinical Correlate: Reflex Threshold Testing May Reveal Type of Hearing Loss
Summary

· Chapter 16. Introduction to the Sensory Mechanics
The Bony Labyrinth
The Membranous Labyrinth
The Vestibular System
The Cochlea
Structures Within the Cochlea
Gross Structures
Fine Details of Features in the Cochlea
Mass and Stiffness Differences Along Basilar Membrane
Review of How the Detailed Features Fit Within the Larger Picture
Cochlear Blood Supply
Innervation of the Cochlea
Summary

· Chapter 17. Advanced Study of the Anatomy of the Cochlea
Hair Cell Height and Number
Stereocilia and Their Tip Links and Side Links
Supporting Cells
Chemical Composition of Endolymph and Perilymph
Comparative Electrical Charges of Fluids in the Cochlea
Potassium Influx Regulates Calcium Coming into Hair Cells
Circulation of Ions
Clinical Correlate: Gap Junctions and Deafness
Neurotransmitter Release
Summary

· Chapter 18. Introduction to Cochlear Physiology
Arrangement of the Cilia Relative to Tectorial Membrane
Mass/Stiffness Gradient of the Basilar Membrane
Review of Divisions and Membranes Within the Cochlea
The In-and-Out Motion of Stapes Footplate Becomes an Up-and-Down Motion of Basilar Membrane, Called the Traveling Wave
The Location of the Maximum Place of Movement on Basilar Membrane Is Determined by the Sound Frequency
The Height of the Traveling Wave Envelope Is Related to Sound Intensity
Ciliary Shearing
Returning to the Concept that the Up-and-Down Basilar Membrane Motion Creates Side-to-Side Shearing of the Hair Cell Cilia
Shearing of Cilia Opens Microchannels in the Cilia and Creates Chemical Changes in the Hair Cell Body
The Active Mechanism Enhances the Motion of the Inner Hair Cell Cilia
Hearing Requires Inner Hair Cell Stimulation
Summary

· Chapter 19. More Hair Cell Physiology
Calcium Channels, Potassium Pumps, and the Active Mechanism
Review of Cellular Chemistry Changes
Prestin Protein Contraction Creates the Active Mechanism
Otoacoustic Emissions Are Sounds That Come From the Cochlea as a Result of the Active Mechanism of the Outer Hair Cells
Tip Links and Insertion Plaques
Clinical Correlate: Use of Otoacoustic Emissions Testing in Neonatal Testing
Clinical Correlate: Temporary Threshold Shift
Summary

· Chapter 20. Overview of Cochlear Potentials and the Auditory Nervous System
Chemical Changes in the Hair Cells and Neurons
The Cochlear Microphonic
The Summating Potential
Action Potentials
Clinical Correlate: VIIIth Nerve Tumors Cause
High-Frequency Hearing Loss
Pattern of Neural Firing Encodes Frequency and Intensity
The Primary Afferent Auditory Pathway
Location of Afferent Neuron Dendrites
Course of the VIIIth Nerve
Cerebellopontine Angle
Nuclei
Primary Auditory Cortex
Clinical Correlate: ABR Testing Measures Synchronous
Neural Discharge
Clinical Correlate: Right Ear Advantage
Introduction to Efferent Neurons
Summary

· Chapter 21. Advanced Study of Cochlear and VIIIth Nerve Potentials
Characteristic Frequency
Cochlear Resting Potentials
Endocochlear Potential
Intracellular Potentials
Cochlear Receptor Potentials
Cochlear Microphonic
Summating Potential
Comparison of the Tuning of the Cochlear Microphonic and the Summating Potential
Clinical Correlate: Ménière’s Disease and Enhanced Summating Potentials
Summary of Cochlear Microphonic and Summating Potential
Action Potentials
Electrical Potentials in Neurons
Refractory Period
Spontaneous Discharge Rates
Threshold of Neural Firing Is Related to Spontaneous Discharge Rate
Firing Rates Influenced by Efferent Innervation
Pure Tones Frequencies and Intensities That Cause a Neuron to Fire Faster Than Spontaneous Rate
Upward Spread of Masking—Masking of One Stimulus by a Second
Neural Tuning Curves
How Neural Tuning Curves are Obtained
Q10 dB Calculations Describe Width of Tuning Curve Tips
Neural Tuning Curve Summary
Summary

· Chapter 22. How Frequency and Intensity Information Is Encoded by VIIIth Nerve Fibers
Rate of Firing of One Neuron Increases as the Stimulus Frequency Approaches Characteristic Frequency
Different Combinations of Frequency and Intensity Can Create the Same Overall Number of Neural Discharges Per Second
Problems with the Theory That Frequency Is Encoded By Rate of Discharge
Pattern of Neural Discharge Encodes Frequency and Intensity *:Return to the Digital System Analogy
Whole Nerve Potentials Versus Single Nerve Potentials to Single Pure Tones
Limits on a Neuron’s Firing “In Phase” with Signals
Clinical Correlate – What the Auditory Brainstem Response Measures and How the Auditory Steady-State Response Differs
Masking of One Sound by a Second Sound
Poststimulus Time Histograms Obtained When Stimulating the Ear with Clicks and the Concept of Preferred Intervals
Period Histograms: Histograms Obtained with Pure-Tone Stimulation
Review of the Response of the VIIIth Nerve to Pure Tones
Response of the VIIIth Nerve to Complex Signals
Additional Information Is Obtained from Early and Late Neural Firing
Summary

· Chapter 23. The Efferent Auditory System
Olivocochlear Bundle
Medial Efferent System
Lateral Efferent System
Crossed and Uncrossed Efferent Fibers
Effect of Activation of the Efferent System
Medial Efferent System Activation
Lateral Efferent System Activation
Other Efferent Pathways
The Acoustic Reflex
Stapedial Reflex Pathway
Effect of Stapedial Reflex Contraction
Role of Tensor Tympani
Acoustic Reflexes Elicited by Nonauditory Stimuli
Summary

· Chapter 24. Peripheral Vestibular Anatomy and Physiology
The Vestibular System Bony and Membranous Labyrinths
Arrangement of the Semicircular Canals
Planes of the Canals of the Right and Left Ears are Aligned
Clinical Correlate: Orienting the Horizontal Semicircular Canal
Anatomy and Physiology of the Semicircular Canals
Structures Within the Ampullae of the Semicircular Canals
Angular Head Motion Directions
Cilia and Kinocilium in the Ampullae
Direction of Endolymph/Cupula Movement That Is Excitatory
The Utricle and Saccule
Hair Cells of the Utricle and Saccule
Vestibular Branch of the VIIIth Nerve
Clinical Correlate: Benign Paroxysmal Positional Vertigo
Clinical Correlate: Vestibular Assessment of Each Branch of the Vestibular Portion of the VIIIth Nerve
Summary

· Chapter 25. Central Vestibular Anatomy and Physiology
Functions of the Balance System
Awareness of Head Position
The Vestibular-Ocular Reflex
Ewald’s First Law
Muscles Controlling Eye Movements
Neural Pathways for Ocular Control
Pathways from Vestibular Nucleus to the Nerves Controlling Eye Movement
Neural Control of Eye Deflection During Head Turn
Limited Range of Eye Deflection
Nystagmus: Repeated Slow Drift, Rapid Saccadic Return Motion
Introduction to Ewald’s Second Law
Summary of the VOR and Introduction to VNG Testing
Velocity Storage
Clinical Correlate: Unilateral Peripheral Lesions Cause
Nystagmus That Beats Toward the Unaffected Ear
Reflexes of the Balance System for Postural Control
Vestibulospinal reflex
Cervicoocular reflex
Cervicospinal and cervicocollic reflexes
Vestibulocervical and vestibulocollic reflexes
Summary of the Functions of Balance and Clinical Implications
Clinical Correlate: Overview of Balance Assessment
Overview of Posturography
Overview of Video- and Electronystagmography
Summary

Section 4: Basic Psychoacoustics

· Chapter 26. Introduction to Psychoacoustics
Threshold for Pure Tones Depends on Frequency
Two Ears Are Better Than One
Under Ideal Circumstances, a Person Can Detect a 1-dB Intensity Change
In General, a 10-dB Increase in Intensity Is About a Doubling of Loudness
Loudness Grows a Bit Differently in the Low Frequencies: An Introduction to Phon Curves
Pitch
When Is a Pure Tone Tonal?
Detecting Change in Pitch
Doubling Frequency Creates a Musical Sameness but Not a Doubling of Pitch
Masking
Upward Spread of Masking
Critical Bands
Temporal Processing
Sounds Are Louder and of Better Pitch if at Least One-Quarter Millisecond Duration
Temporal Order Detection
Gap Detection
Summary and Implications for Speech Perception

· Chapter 27. Classical Psychoacoustic Methodologies
Classic Psychoacoustic Methods
Method of Limits
Effect of Instruction
Response Latency and False Positive Responses
Effect of Using Increasing Versus Decreasing Intensity Runs
Clinical Correlate: How Instruction Affects Patients’ Responses
Clinical Correlate: Nonorganic Loss Detection Using Lack of False Positive Responses and Latency Inconsistencies
Clinical Correlate: Ascending Testing in Nonorganic Loss
Method of Adjustment
Similarity of Results of Method of Adjustment and Method of Limits
Method of Constant Stimuli
Number of Trials and Step Size
Newer Methods
Adaptive Up-Down Methods
Introduction to Forced-Choice Methods
Threhhold Is Generally Not 50% Correct Identification in a Forced-Choice Procedure
Introduction to Signal Detection Theory
Scaling Procedures
Magnitude Estimation
Clinical Correlate: Scaling Procedures Are Used Clinically
Magnitude Production
Fractionation
Cross-Modality Matching
Summary

· Chapter 28. Signal Detection Theory and Advanced Adaptive Approaches
Signal Detection Theory
Understanding “Magnitude of the Sensory Event”
Signal Plus Noise Perception
Criterion Points for Decision-Making and How Hit and Correct
Rejection Percentages Reveal Spacing Between the Noise and
Signal-Plus-Noise Distributions
Altering Subject Criteria in Signal Detection Theory and Receiver
Operating Curves
The Magic of d’
Clinical Correlate: Clinical Tests Have d’ Values
Adaptive Methods to Determine the Signal Level That Is Correctly Detected a Given Percentage of Time
Block Up-Down and Transformed Up-Down Procedures
Interleaving Runs
Parameter Estimation by Sequential Testing
Gridgeman’s Paradox
Preference Testing in Hearing Aid Customization
Paired-Comparisons
Summary

· Chapter 29. Threshold of Hearing, Loudness Perception, and Loudness Adaptation
Absolute Threshold of Hearing
Mimimal Audible Pressure and Field
Binaural and Equated Binaural Thresholds
Effect of Stimulus Duration on Absolute Threshold
Effect of Stimulus Repetition Rate
Difference Threshold for Intensity: DLI
Spectral Profile Analysis
Clinical Correlate: Short-Increment Sensitivity Index
Loudness Perception
Loudness Level
Decibel Scales Revisited
Loudness Scaling
Loudness Adaptation
Clinical Correlate: Tone Decay and Reflex Decay Testing
Temporary Threshold Shift
Summary

· Chapter 30. Calculating Loudness
Physiological Correlates of Loudness and Loudness Growth
The Transfer Function of the Ear
Role of the Active Mechanism
Spread of Activity Along the Basilar Membrane
Calculating Loudness of Pure Tones
Complex Tone Loudness
Summary

· Chapter 31. Basics of Pitch Perception
Pitch Perception
The Limits of Tonal Perception
Pitch Perception Is Intensity Dependent
Pitch Perception Is Duration Dependent
Pitch Scaling
The Mel Scale of Pitch
Octave Scales
Bark Scale Introduced
Just Noticeable Difference of Frequency
Changes in DLF with Frequency
Changes in DLF with Intensity
Perception of Two Tones and of Distortions
Beats and Simple Difference Tones
Summation Tones, Other Difference Tones, and Aural Harmonics
Summary

· Chapter 32. Introduction to Masking
Tone-on-Tone Masking
Critical Bands
Clinical Correlate: The Audiometer’s Masking Noise
Summary

· Chapter 33. More about Masking and Cochlear Frequency Distribution
Masking Pure Tones with White Noise and Narrow-Band Noise: Critical Bands and Critical Ratios
Level per Cycle Calculations
Critical Bands in Hz and dB
A Critical Band Is also Called a Bark
How Critical Bands Vary with Frequency
Fletcher’s Theory of Critical Ratio
Equivalent Rectangular Bandwidths
Other Ways to Evaluate Critical Bands
The Relationship Between DLF, Critical Bands, Critical Ratios, and Equivalent Rectangular Bandwidths
Clinical Correlate: Acoustic Reflexes to Pure Tones and Broadband Noise
Comodulation Release from Masking
Remote Masking
Summary and Some Further Analysis

· Chapter 34. Psychophysical Tuning Curves
Psychophysical Tuning Curves
How PTCs Are Obtained and Interpreted
Correlation to Traveling Wave Locations
Families of PTCs
Tips, Tails, and Q-10’s
Neural Tuning Curves Revisited
The Link Between PTCs and Neural Tuning Curves
Summary and a Confession

· Chapter 35. Temporal Processing
Review of Temporal Integration for Threshold-Level Stimuli
Review of Duration Effects on Pitch Perception
Gap Detection
Gap Detection Ability Is a Function of Frequency
Gap Detection Ability Is Related to the Auditory Filter Bandwidth
Detection of Gaps in White Noise Uses the High-Frequency Cochlear Filters
Clinical Correlate: Auditory Processing Testing of Gap Detection
Temporal Successiveness
Clinical Correlate: Auditory Processing Testing of Temporal Successiveness
Temporal Discrimination
Temporal Discrimination Relates to Distinguishing Voiced from Unvoiced Consonants
Temporal Modulation Transfer Functions
Summary

· Chapter 36. Temporal Masking
Forward Masking – Masker Precedes Probe Signal
Magnitude of the Effect
Physiologic Explanations
Forward Masking Psychophysical Tuning Curves Are Sharper
Backward Masking – Masker Follows the Probe Signal
Magnitude of the Effect
Physiologic Explanation
Summary

· Chapter 37. Binaural Hearing
Binaural Summation
Improved DLI and DLF Ability Binaurally
Clinical Correlate: Monaural versus Binaural Amplification
Binaural Beats
Central Masking
Binaural Fusion
Localization
Temporal Cues to Localization
Intensity Differences
Combined Effect of Intensity and Phase Differences
Central Nervous System Cells Are Responsive to Phase or Intensity Differences
Lateralization
Interaural Time Difference
Interaural Intensity Differences
Clinical Correlate: Stenger Test for Nonorganic Unilateral Hearing Loss
Combined Effects of Intensity and Phase
Why Is Lateralization a Different Phenomenon from Localization?
Masking Level Differences
Clinical Correlate: Binaural Advantage to Hearing Aids
Summary

· Chapter 38. Introduction to Results of Psychoacoustical Assessment of the Hearing-Impaired
The Effect of Hearing Loss on Audibility of Tones and Speech
Effect of Loss Type and Severity
Loss of Sensitivity for Pure Tones Predicts Loss of Speech Perception Ability
Articulation Index Predictions of Speech Understanding Are Imperfect
Cochlear Loss Causes Recruitment
Difference Limens for Intensity
Threshold Temporal Summation Effects
Widened Psychophysical Tuning Curves
Cochlear Dead Regions
Off-Frequency Listening
Audiometric Characteristics of Dead Regions
What Is Perceived When Off-Frequency Listening Occurs?
Psychophysical Tuning Curves for Dead Regions
The Threshold Equalizing Noise Test
Enhanced DLFs Near Dead Regions?
Amplification for Those with Dead Regions
Clinical Correlate: Frequency Compression Hearing Aids and Short-Electrode Cochlear Implants
Gap Detection Thresholds
Results with White Noise Stimuli
Gap Detection Results for Pure Tones Depend on Stimulus Intensity Levels
Gap Detection Should Theoretically Be Better in Hearing-Impaired
Temporal Modulation Detection Ability Is Good if Signal Is Fully Audible
Poorer Pitch Perception Abilities
Summary

· Appendix A. The Math Needed to Succeed in Hearing Science
· Index