Improving Speech Intelligibility in Adults: Clinical Application of Evidence-Based Strategies

First Edition

Connie K. Porcaro

Details: 273 pages, B&W, Softcover, 7" x 10"

ISBN13: 978-1-63550-357-9

© 2023 | Available


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Being intelligible to a listener means getting your message across and improving speech intelligibility is one of the most common goals for clients working with a speech-language pathologist (SLP). Improving Speech Intelligibility in Adults: Clinical Application of Evidence-Based Strategies is a professional resource for practicing SLPs working with adults with communication disorders, such as dysarthria, acquired apraxia of speech, and voice disorders. 

This book incorporates current research findings to support the use of evidence-based strategies in clinical situations. While other books may focus on “drilling” and “practicing” a list of words, sentences, and topics to use with a client to change their behaviors, Improving Speech Intelligibility in Adults uniquely focuses on the speaker and the listener in tandem. The author takes a noteworthy approach in how the listener can change behaviors to assist with understanding. The text presents a comprehensive approach to improving speech intelligibility by including ways to enhance the communication environment during in-person or teletherapy exchanges to enhance understanding between speaker and listener.



“This book … offers a unique perspective not seen in most books on speech sound treatments, suggesting that a communicative partner approach be applied when it can aid in functional communication between speakers and listeners.
… the goal of the book is to equip readers with an ability to bridge the gap between aspects that influence intelligibility according to available research with what works well clinically.
The target audience includes practicing speech language pathologists (SLPs) and those studying speech-language pathology. The book is a professional resource that can be used alongside diagnostic and therapeutic services for adults with acquired communication disorders such as dysarthria, acquired apraxia of speech, and voice disorders.
The book includes a brief summary of each chapter in the preface, which immediately aids in navigating the text. Each chapter also contains a more comprehensive summary reviewing the information as well as at least one case study and a list of references…
This book serves as a guide for expanding SLPs' thinking in areas such as working with communicative partners to make changes in the environment, thus enabling increased functional communication. It succinctly states, "being understood is everything to our clients." The book effectively guides clinicians to use internal evidence (data and observations collected on individual clients) when determining treatment plans for reduced intelligibility. Therefore, its emphasis on using one of the three main areas of evidence-based practice (EBP) in speech-language pathology is valuable to clinicians servicing patients with reduced intelligibility.”

–Melissa Raymond, MS, Biola University, from Doody’s Reviews (July 2023)


Chapter 1. Introduction of Intelligibility and Related Concepts

Key Points 
Definitions of Intelligibility,
Comprehensibility, and Related Measures

Communication Participation

Components of a Communication Exchange

Theories of Communication Feedback
Communication Channels 
Communication Noise

Physical Noise 
Physiological Noise 
Psychological Noise 
Semantic Noise

Shared Experiences Between Communicators

Impaired Communication 
Consideration of Function and Disability 
Related to Intelligibility
Integrating Science and Clinical Practice to Improve Intelligibility

Using Evidence-Based Practice for Clinical Decisions
Exploring Our Role in Bridging Research to Clinical Practice
Utilizing Technology Appropriately for Best Practice

Case Study Introduction 
References Appendix 1–1. References for ICF 
Application to Specific Disorders Related to Reduced Intelligibility

Chapter 2. Impact of Speaker-related Factors on Intelligibility

Key Points 
Speech Subsystems and Effect on Intelligibility
Intelligibility Issues Related to Speakers With Dysarthria


Intelligibility Issues Related to Speakers With Acquired Apraxia of Speech

Respiration, Phonation, and Resonance 
Articulation and Fluency 
Prosody and Rate

Intelligibility Issues Related to Speakers With Voice Disorders

Voice Disorders Related to Neurologic Etiology
Voice Disorders Related to Functional Etiology
Voice Disorders Related to Organic Etiology
Voice Disorders Related to Head and Neck Cancer

Influence of Head and Neck Cancer Treatment on Voice
Electrolaryngeal Speech 
Esophageal Speech 
Tracheoesophageal Speech

Effect of Face Masks and Social Distancing on Intelligibility
Dysarthria Case 
Voice Disorders Case 

Chapter 3. Assessment of Speaker Structures and Functions: Subsystem Evaluation to Determine Contributions to Reduced Intelligibility

Key Points 
Case History Questions 
Standardized Tests and Rating Scales for Speech and Voice Assessment

Patient Reported Outcome Measures 
Published Dysarthria Measures 
Published Adult Apraxia of Speech Measures
Published Voice Disorders Measures

Factors Related to Collecting Recorded Samples

Options for Recording Virtually 
Considerations of Recording With Face Masks

Auditory-Perceptual Evaluation

Evaluation of Respiration

Posture and Body Movement 
Duration Measures 
Breath Group Measures 
Conversational and Reading Measures Related to Respiration

Evaluation of Phonation

Measures of Loudness
Measures of Pitch 
Measures of Quality

Evaluation of Resonance
Evaluation of Articulation

Speech-like Movements and Rates
Speech Sound Inventory 
Connected Speech Sample

Evaluation of Prosody

Dysarthria Case 
Voice Disorder Case 
Appendix 3–1. Communicative 
Effectiveness Survey—Revised (CESR)Appendix 3–2.
The Communication 92 Participation Item Bank—General Short Form

Chapter 4. Factors Related to Meaningful Assessment of Intelligibility

Key Points 
Clinician’s Use and Perceptions of Intelligibility Measures
Intelligibility Assessment

Subjective Intelligibility Measurement Tasks
Objective Intelligibility Measurement Tasks

Influences on Intelligibility Measures

Factors Related to the Speaker

Speech Rate 
Personal Speaker Factors

Factors Related to the Message

Type of Message
Predictability of Message 
Presentation Mode of Message

Factors Related to Listeners

Individual Listener Variability 
Listener Task 
Familiarity with Speaker 
Familiarity with Message Age

Factors Related to the Communicative Environment

Recording Equipment 
Auditory-Only versus Auditory-Visual 
Presentation Mode Listening Conditions

Assessment of Comprehensibility, Efficiency, and Naturalness
Intelligibility Measures Related to Voice Disorders and Head and Neck Cancer
Use of Technology in Intelligibility Assessment

Dysarthria Case 
Voice Disorders Case 
References Appendix 4–1.
Medical Research Council Institute of Hearing Research Audio-Visual Adaptive Sentence Lists
Appendix 4–2. Hearing in Noise Test Sentence Lists
Appendix 4–3. Checklist for Considerations Related to Assessment of Intelligibility

Chapter 5. Speaker Subsystem Management Strategies to Improve Intelligibility

Key Points 
Guiding Frameworks for Management Decisions

International Classification of Function 
Evidence-Based Practice

Subsystem Contribution and Management


Diaphragmatic-Abdominal Breathing 
Increasing Upper Body Tone 
Body Positioning 
Controlling Exhalation 
Generating Appropriate Loudness Levels 
Muscle Strength Training 
Using Optimal Breath Groups Inspiratory Checking


Using Effortful Closure 
Timing Phonation with Exhalation 
Low Impact Voicing 
Utilizing Relaxation Techniques 
Speaking with High Phonatory Effort 
Phonation Resistance Training Exercises (PhoRTE)
Using Holistic Voice Therapy Programs 
Implementing Vocal Hygiene Enhancing Loudness with Prosthetics


Modifying Habitual Speech: Clear and Loud Speech
Deciding on Use of Nonspeech Oral Motor Exercises (NSOME)


Modifying Speech Rate 
Marking Stress Patterns 
Using Intonation

Management Related to Specific Communication Disorders

Adult Apraxia of Speech Head and Neck Cancer

Using Outcome Measures During Management
Dysarthria Case 
Voice Disorder Case References

Chapter 6. Speaker Management Strategies to Improve Intelligibility and Functional Communication

Key Points 
Speaker-Related Strategies

Slowing Speech Rate 
Making Speech Clear

Message-Related Strategies

Using the Most Effective Message Length and Type
Choosing Predictable Messages

Communication-Related Strategies

Gaining Listener Attention Before
SpeakingSetting Ground Rules for Communication 
Providing the Topic for a Conversation 
Signaling Changes in Topic 
Using Gestures to Provide Added Information
Providing Cues with Alphabet Supplementation
Watching for Signs of Listener Comprehension
Scheduling Important Discussions 
Repairing Communication Breakdowns 
Incorporating All Useful Modalities 
Considering the Impact of a Face Mask on Communication

Strategies Specific to Speakers With Voice or Head and Neck Cancer
Intervention Objectives to Be Facilitated by the Clinician
Dysarthria Case 
Voice Disorders Case 
Appendix 6–1. Checklist for Speaker Strategies to Maximize Functional Communication

Chapter 7. Listener Strategies to Improve Intelligibility and Functional Communication

Key Points 
The Importance of Collaborative Efforts 
Factors Related to Listener Inclusion in Management
Listener Variability

Listener Age 
Listener Cognitive Abilities 
Perceived Listener Effort 
Listener Adaptability 
Listener Experience with Speech Disorders
Listener Familiarization

Communication Entrainment 
Listener Barriers and Categories of Strategies
Functional Listener Strategies

Using Active Listening Skills 
Watching for Signals That a Conversation Is Starting
Gaining Topic Knowledge 
Utilizing Visual Information 
Using All Available Information 
Setting Yourself Up to Be the Best Listener You Can Be
Discussing Rules for Interaction With the Speaker
Providing Feedback and Encouragement

Specific Strategies Related to Communicating With Individuals With Voice or Head and Neck Cancer

Listener Strategies for Speakers With Dysphonia
Listener Strategies for Speakers Following Head and Neck Cancer Treatment

Effect of Unsuccessful Communication on Speakers 
Dysarthria Case 
Voice Disorders Case 
References 232
Appendix 7–1. Checklist for Listener 240 Strategies to Maximize Understanding

Chapter 8. Strategies to Alter the Communication Environment for Better Understanding

Key Points 
Identifying Environmental Barriers 
Approaches for Dealing With Communicative Noise

Physiological Noise 
Psychological Noise 
Semantic Noise Physical Noise

Adaptation to Environment 
Environmental Modification

Improving Proximity Between Speakers and Listeners
Reducing or Eliminating Background Noise
Improving Access to Visual Information 
Reducing or Eliminating Distractions 
Using External Aids
Speaking Clearly When Wearing Face Masks
Using the Phone Effectively 
Adjusting Audio Settings for Video Chat Communication

ZOOM Audio Settings 
Smart Phone or Tablet Audio Settings
Skype Audio Settings

Impact of Communicative Environment on Speakers With Head and Neck Cancer
Dysarthria Case 
Voice Disorders Case 
Appendix 8–1. Situational Intelligibility Survey
Appendix 8–2. Checklist to Maximize Communication Potential by Modifying the Environment


Connie K. Porcaro

Connie K. Porcaro, PhD, CCC-SLP, is an Associate Professor in the Department of Communication Sciences and Disorders at Florida Atlantic University (FAU), where she instructs courses covering voice, speech, and swallowing disorders in adults, and lectures annually for future physicians at the FAU Medical School on the topics of adult neurogenic speech and language disorders. Dr. Porcaro is certified by the American Speech-Language-Hearing Association and has worked as a speech-language pathologist for more than 25 years with clients of all ages. Her main area of research is focused on intelligibility in patients with speech and voice disorders and how speakers and listeners can have improved communication. Dr. Porcaro is a frequent presenter at the Annual Convention of the American Speech-Language-Hearing Association and state association conventions as an invited speaker on the topic of intelligibility. She has received grant funding from the FAU Healthy Aging Research Initiative to investigate voice and swallowing changes in healthy elderly individuals, and she has received grant funding from the Parkinson Voice Project to facilitate training for graduate students who provide free-of-cost speech therapy for individuals with Parkinson’s disease.

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