Relating acoustics and human outcome measures in hospitals

302 Pages·2012·2.84 MB·English

RELATING ACOUSTICS AND HUMAN OUTCOME MEASURES IN
HOSPITALS

A Dissertation
Presented to
The Academic Faculty

by

Timothy Yuan-Ting Hsu

In Partial Fulfillment
of the Requirements for the Degree
Doctor of Philosophy in the
School of Mechanical Engineering

Georgia Institute of Technology
May 2012
RELATING ACOUSTICS AND HUMAN OUTCOME MEASURES IN
HOSPITALS

Approved by:

Dr. Erica Ryherd, Advisor Dr. Craig Zimring
School of Mechanical Engineering School of Architecture
Georgia Institute of Technology Georgia Institute of Technology

Dr. Kenneth Cunefare Dr. Kerstin Persson Waye
School of Mechanical Engineering Occupational and Environmental
Georgia Institute of Technology Medicine
Sahlgrenska Academy
Dr. Aldo Ferri University of Gothenburg
School of Mechanical Engineering
Georgia Institute of Technology

Date Approved: March 9, 2012
To my parents,
ACKNOWLEDGEMENTS

This dissertation could not have been completed without the generous support and
help from many people. I genuinely wish to thank Erica Ryherd, my advisor, for the
tremendous support and guidance for the development and completion of his dissertation.
She has been a constant source of inspiration and knowledge without which this
dissertation would not have been possible. I would also like to thank my committee
members, Dr. Kenneth Cunefare, Dr. Aldo Ferri, Dr. Craig Zimring and Dr. Kerstin
Persson Waye. Additionally, I wish to show a special gratitude to the School of
Mechanical Engineering, the Acoustical Society of America, and the Swedish Council for
Working Life and Social Research for providing the opportunity and funding to pursue
this work.
This dissertation has been deeply involved with collaborators from around the
world. Dr. Kerstin Perrson Waye has spearheaded this project in Sweden and has been an
invaluable resource. Additionally, Dr. Jeremy Ackerman and Jerome Abramson (Emory
University) have provided ample support with regards to medical and statistical
questions. Dr. James West, Dr. Colin Barnhill, Dr. Ilene Busch-Vishniac, the acoustics
lab at Johns Hopkins University, and the wonderful staff at the Johns Hopkins Hospital
Weinberg Building have been incredible colleagues to work with and without their
initiative, this Johns Hopkins Hospital project would not have happened. An additional
thanks is needed for DuPont and Natalia Levit for the support in developing the new
absorptive panels we used.
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My lab group at Georgia Tech have been invaluable in this dissertation. A very
special recognition is needed for Jonathan Graham for his incredible hard work. Other lab
mates that have been essential have been: Dr. Selen Okcu, Arun Mahapatra, Michael
Moeller, Joe McKenzie, Nick Reagan, Allison McInteer, and all the other lab mates past
and present. I have enjoyed every moment that I have worked with you.
I also wish to thank Dr. Jerry Ulrich and the Choral Department at the Georgia
Tech School of Music. Without this artistic and musical part of my life over the last
several years, this dissertation would not have come to fruition. I am so proud of our
magnificent musical accomplishments and I am honored to have been a part of the choral
groups. I deeply love all of my choral students and I wish that we will continue to make
great music together.
I must thank all my friends for tolerating my craziness and over-scheduled life.
The road to the dissertation cannot be completed without the presence of these friends.
They have given me support, songs, sanity, laughs, and special stories that I will keep
with me for the rest of my life. Last, but not least, I must thank my parents and sister for
the many years of love and support. They taught me strong values and laid the foundation
that made this work possible. They have truly been an inspiration and have guided me in
every step of the process.

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TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS iv
LIST OF TABLES xi
LIST OF FIGURES xiii
LIST OF EQUATIONS xvii
LIST OF SYMBOLS AND ABBREVIATIONS xviii
SUMMARY xxiii
CHAPTER 1 - INTRODUCTION 1
1.1 Overview 1
1.2 Motivation and Hypotheses 2
1.2.1 Contribution Breakdown 4
1.3 Background Literature/Previous Research 6
1.3.1 Noise in hospitals 6
1.3.2 Patient Effects 9
1.3.3 Review of Physiological Effects 11
1.3.4 Patient response 13
1.3.5 Staff response 28
1.3.6 Non-hospital staff potential outcomes 36
1.3.7 Speech intelligibility in non-hospital settings 38
1.3.8 Visitor response 39
1.4 Discussion 40
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1.5 Patient and Staff Effects Summary 52
1.6 Research Goals and Contributions 52
CHAPTER 2 - ACOUSTIC PRINCIPLES AND DATA ANALYSIS TECHNIQUES 54
2.1 Metrics Derived from Sound Level Meter Measurements 54
2.1.1 Background Noise 55
2.1.2 Fundamental SLM Metrics 56
2.1.3 Time Response 58
2.1.4 Weighting Networks 58
2.1.5 Occurrence Rate 59
2.1.6 DL 60
2
2.2 Impulse Response 62
2.2.1 Measurement Techniques 63
2.2.2 Metrics derived from the impulse response 65
2.3 Noise Metrics 66
2.3.1 Noise Criteria (NC) 66
2.3.2 Balanced Noise Criteria (NCB) 68
2.3.3 Room Criteria (RC) 69
2.3.4 Room Criteria Mark II (RC Mark II) 70
2.4 Speech Intelligibility 71
2.4.1 Articulation Index 71
2.4.2 Speech Intelligibility Index 73
2.5 Audio Recordings 74
2.5.1 Digital and Binaural Recordings 74
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2.6 Psychoacoustic Principles 75
2.6.1 Speech Interference Level 76
2.6.2 Loudness 76
2.6.3 Sharpness 77
2.6.4 Fluctuation Strength 78
2.6.5 Roughness 78
2.6.6 Just Noticeable Difference for Psychoacoustic Metrics 78
2.6.7 Just Noticeable Difference for Reverberation Time 79
2.7 Statistics Principles 80
2.7.1 Correlations 80
2.7.2 Linear Regression 82
2.7.3 Curve Estimation 82
2.7.4 Risk Ratio 83
2.8 Conclusion 84
CHAPTER 3 - METRICS AFFECTING PATIENT OUTCOMES (SWEDEN STUDY)85
3.1 Introduction 85
3.2 Methodology 86
3.2.1 Environment 86
3.2.2 Types of measurements 87
3.2.3 Acoustic Measurements 87
3.2.4 Acoustic measurements 88
3.2.5 Patient physiological measurements 89
3.3 Results 90
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3.3.1 Traditional acoustic metrics 90
3.3.2 Psychoacoustic Metric Results 102
3.3.3 Psychoacoustic Metrics Discussion 109
3.4 Relating acoustic metrics to patient physiology 111
3.4.1 Background Physiological Data 111
3.4.2 Correlations 112
3.4.4 Linear Regression and Curve Estimation 118
3.4.5 Risk Ratio 118
3.4.6 Alarms 126
3.4.7 Speech Intelligibility 131
3.5 Conclusions and Interpretation 132
CHAPTER 4 - METRICS AFFECTING STAFF OUTCOMES (JOHNS HOPKINS
HOSPITAL STUDY) 139
4.1 Introduction 139
4.1.1 Ward Background 140
4.1.2 Panels as developed by DuPont and JHU 142
4.1.3 Previous Xorel® Noise Control Solution 143
4.1.4 Optimized Tyvek Noise Control Solutions 145
4.2 Methodology 147
4.2.1 Installation of Tyvek® Panels in Weinberg 147
4.2.2 Acoustic Methodology 148
4.2.3 Staff questionnaire 152
4.2.4 Limitations in methodology 153
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4.3 RESULTS AND DISCUSSION 154
4.3.1 Phase One: Development of “Optimized” Panels 154
4.3.2 Phase Two: Acoustic results of treated and untreated wards 157
4.3 Staff questionnaire results 178
4.4 DISCUSSION AND CONCLUSIONS 181
CHAPTER 5- CONCLUSION 187
APPENDIX A – CLUSTER PLOT METHODS 195
APPENDIX B – CLUSTER PLOT MATLAB CODE 199
APPENDIX C – DELAYED CORRELATIONS RESULTS 212
APPENDIX D – LINEAR REGRESSION 215
APPENDIX E – CURVE ESTIMATION 221
APPENDIX F – RISK RATIO MATLAB CODE 230
APPENDIX G – JOHNS HOPKINS QUESTIONNAIRE 261
REFERENCES 268
VITA 279

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