AN EVALUATION OF CLASSROOM SPEECH AND NOISE LEVELS IN TERMS OF SPEECH INTELLIGIBILITY IMPLICATIONS

79 Pages·3.128 MB·English

by  BRYNES, JACOB

Sponsoring Committeej Professor Cyrus W. Barnes, Professor
John G. Rockwell and Associate Professor
William J. Farma
AN EVALUATION OF CLASSROOM SPEECH AND NOISE LEVELS IN TERMS
OF SPEECH INTELLIGIBILITY IMPLICATIONS
JACOB BRINES
Submitted in partial fulfillment of the
requirements for the degree of Doctor of
Philosophy in the School of Education of
New York University
1953
>
The student hereby guarantees that no part of the dissertation
: or document which he has submitted for publication has been hereto­
fore published and (or) copyrighted in the United States of America;
except in the case of passages quoted from other published sources;
that he is the sole author and proprietor of said dissertation or
document; that the dissertation or document contains no matter which,
if published, will be libelous or otherwise injurious, or infringe
in any way the copyright of any other party, and that he will defend,
indemnify and hold harmless New York University against all suits
and proceedings which may be brought against all claims which may be
made against New York university by reason of the publication of said
dissertation or document.
PREFACE
This investigation stems from a curiosity as to the
fluctuation of speech Intelligibility in classrooms and a
desire for its improvement, when information is lost in
passing among a classroom’s inhabitants, an educational loss
is likely. A teacher is, therefore, justifiably concerned
about unintelligible speakers, subnormal hearers and in­
terfering classroom noise.
The author wishes to acknowledge the helpful coop­
eration of pupils, teachers and school administrators in
securing acoustic data. Several faculty members at New York
University gave valuable assistance at different stages of
the investigation.
J. B.
ii
CONTENTS
CHAPTER PAGE
I PURPOSE OF THE RESEARCH...................... 1
Speoific Questions.................... 1
Definition of TermB....................• 2
Significance... ....... 3
Delimitations.,.* • • 4
II RELATED CONCEPTS OF SPEECH COMMUNICATION...... 6
III MEASURING SPEECH AS AN INFORMATION CARRIER 13
Artioulation Testing................... 13
Reverberation, Noise and Articulation
Scores................................ 13
Speakers and Articulation Scores........ 15
Hearers and Articulation Soores......... 15
IV AN INDEX OF INTELLIGIBILITY................... 17
Basic Assumptions................. 18
Language......................... 18
Speakers.......................... 19
Hearers........................... 20
Room Reverberation Time............ 20
Noise Masking.20
Speech to Noise Ratio.............. 21
Three Hypotheses Concerning Trends in the
Index. ........................... 22
V DESIGN OF THE RESEARCH....................... 24
Selection of Sohools.................. 25
Measuring Speech and Background Noise
Levels............................... 26
Gathering Additional Data........ ...... . 38
VI THE STATISTICAL INQUIRY.............. 29
Speeoh Levels Versus Noise Levels....... 39
Significance of Correlation Co­
efficient............... ........ 31
Test for Linearity of Regression 31
Regression Equation of Y on X 31
Standard Error of Estimate......... 33
Indications of Unintelligible Speech 32
Grade, Period and School Effects on
Intelligibility........................ 34
Computation for Analysis of Variance. 36
iii
CHAPTER PAGE
Grades. ..................... 39
Schools*............. 41
Differences Among Schools 41
Differences Between Specific
Schools................ 42
Effects of Class Size on Intelligibility.. 44
Analysis.......................... 44
Effeots of Session Duration on
Intelligibility........................ 46
Analysis......................... 46
Teacher Speech......... 47
Mean Levels....................... 48
Relation of Mean Level to Contribution 49
Rearing for Classroom Speech........ 50
VII CONCLUSIONS AND RECOMMENDATIONS.............. 52
Articulation Testing in Education......... 52
Speeoh Intelligibility and Noise Levels... 53
Certain Possible Influences on
Intelligibility........................ 55
Scheduling Implications...... 55
Implications of Certain School
Plant Factors.......••••......... 57
Class Size Implications............. 59
Lesson Duration Implications....... 60
Teacher Speeoh....................... 60
Hearing Loss for Classroom Speech. ..... 62
APPENDIX.................................... 65
BIBLIOGRAPHY................................ 70
TABLES
I Distribution of Sessions by School, Grade and
Period...... ••••..... ••••••••............ 24
II Mean Speech to Noise Ratios (As Pressure
Ratios) of Sessions Distributed Among
Schools, Grades and Periods of Day......... 35
III Two Way Summary of Speeoh to Noise Ratio
Data According to Period and Grade.. 36
IV Two Way Summary of Speech to Noise Ratio
Data According to School and Grade..........• 36
V Analysis of Variance. ••••••••. .......... 38
VI Analysis of Grade Variance by Periods. ...... 40
VII F Test of Variance ...... 41
VIII Differences Between Schools According to
Level of Significance .............. 44
IX Data for Six Smaller Classes. ...... 45
X Data for Six Larger Classes......••••••...... 46
iv
TABLE PAGE
XI Scale of Standard Scores Based on the Mean
Speech Levels of Thirty Teachers......... 48
XII Mean Speech Levels of Thirty Teachers and
Numbers of Samples of Their Speech,........ 49
XIII Teacher Mean Speech Level and Percentage of
Samples per Grade.,...... 50
XIV Frequency Distributions of Mean Speech and
Noise Levels for Forty Sessions with Third
Grade Classes...... 51
XV Average Absorptivity Characteristics for
Children and Adolescents................ 66
XVI Class Size, Classroom Dimensions and
Reverberation Time........ 67
XVII Speech and Noise Level Samples from
Session IN-3-1......................... 69
FIGURES
1. Correlation Between Mean Speech and Mean
Noise Levels for 120 Sessions 30
2. Field Patterns of Classroom Noise from Two
Univent Devices (Measured with Rooms Empty)
in School 2N........................... 68
v
CHAPTER I
PURPOSE OP THE RESEAROH
The purpose of this researoh is to determine, by analys­
ing ola8• room speeoh and noise levels, the anssers to oertain
questions dealing with speeoh intelligibility* These ques­
tions are related to teacher speeoh, hearing loss for speeoh
and methods for improving speeoh intelligibility*
aegglflq Qtteatlon*
1* What speeoh and noise levels existed during oertain
olass sessions, and how are these levels related to the speeoh
Intelligibility present?
3* What do the findings for the first question laply as
to the possibility of improving speeoh intelligibility in
classrooms by
a. Scheduling olass aotlvitles?
b* Planning olassroom looation and design?
o. Controlling the sise of a olassT
d* Controlling the duration of a lesson?
3* How oan a speeoh level soale, as derived by this in­
vestigation, be useful in rating a teacher' s speeoh intell­
igibility?
4, How oan the samples taken of olassroom speeoh and
noise levels provide valid bases for determining hearing loss
for the speeoh found in third grade classrooms?
2-
D.flnltlon of T»m.
Speeoh levels- measures of the energy of desired speech
sounds ms indicated by a sound level meter.
Xoise levels- measures of the energy of undesired sounds
as indioated by a sound level meter,
Speeoh intelligibility- the effiolenoy of speeoh as a
means of communication, Speeoh intelligibility is measured
quantitatively by the articulation test scores aohleved dur­
ing articulation testing, 8uoh testing employs speakers who
read from syllable, nord or sentenoe lists to a group of lis­
teners, The peroentage of items oorreotly transcribed by the
latter is oalled the articulation score; this score is ac­
cepted as a measure of the intelligibility of speech,1
Hearing loss for speeoh- that reduction in an articula­
tion soore which is oaused by a hearing disability.
Session- a customary olass meeting whioh represents
thirty to sixty minutes of speeoh-oentered activity,
fitPlWWHMT
This researoh assumes speeoh intelligibility to be a
vital Ingredient in classroom eduoation. It further believes
that a study of this speeoh characteristic should be made
under valid environmental conditions. Therefore, the present
investigation is based on an acoustic survey of thirty elemen­
tary classes taken during regular meetings. The main logio
1* J, P, Egan, "Articulation Testing Methods II", Office of
aolentlflc Research and Development. Report
(lovember1944}, p. 1.
-3-
of the inquiry follows.
Articulation soores define the efficiency of speeoh as a
means of communication* Soores largely depend on the differ­
ence in loudness between speech and background noise. This
difference in loudness provides, therefore, an index of speeoh
intelligibility* Aooustio measurements taken during regular
meetings of classes show oertain quantitative trends in the
index* These trends are statistically analysed to determine
whether they are the result of oertain olass, time of day or
school plant factors* The purpose of this analysis is to
reoommend validated methods for improving speeoh intelligi­
bility in olassrooms* Validation is accomplished by findings
which demonstrate effects on the intelligibility index because
of class, time of day or school plant factors*
Speakers try to offset noise interference by louder
speech* This research analyzes the levels of speeoh produced
for different levels of background noise* The purpose is to
determine whether olassroom speakers maintain a constant in­
telligibility index despite higher noise levels. If suoh be
the case, then reductions in classroom noise do not promise
improvements in speeoh intelllgbillty.
Acoustic measurements of teacher speech during olass
meetings produoe a scale based on the mean speeoh levels of
thirty teachers* The uBe of this scale in rating a teacher'•
olassroom intelligibility is desoribed*
Measures derived from the levels enoountered during the
third grade sessions provide a basis for measuring the hearing
loss for speeoh in third grade classes. The advantage of ar­
ticulation testing over audiometrio testing is discussed*
Delimitations
This study is Halted by the precision of the sound meas-
uring instrument! and the teohnique of sound aeasureaent ahioh
sere used* Suoh tools sere seleoted as feasible for a single
investigator to measure sound levels during regular olass
sessions*
This research liaits itself to a speeoh intelligibility
viewpoint in oonsiderlng its speeoh and noise level data.8
The emotional or nervous tension implications will be disre­
garded. The investigation would otherwise be extended beyond
reasonable limits.3
The findings are limited in predictive value to the typee
of sessions encountered. Trying for an unbiased selection of
schools and olass aotivlties, wide distributions were found in
the location and design of the school plants as well as in the
kinds of lessons observed. It is likely that large deviations
from the studied speeoh levels, noise levels or olassroom de­
signs may be found. An external source of loud noise, suoh
as a busy railroad or factory, may be very near the school.
1. General Radio Company. The Boise Primer, p. 15.
L. L. Beranek. Aooustio Meaeuramenta, p. 890.
3. K. D. Kryter, "The Effects of Noise on Man". Journal of
SB2£2& ggflJl.Bg Disorders. Monograph Supplemeni T,
p. 83.
3. . p. 31.