Effects of Feedback and Exposure on Speech Intelligibility Judgments

1
Effects of Feedback and Exposure on Speech
Intelligibility Judgments Lee W. Ellis,
Ph.D. Svetlana Beltyukova, Ph.D.
ABSTRACT

• Procedures
• The 55 participants were randomly assigned to
  five groups, each with 11 participants.
  Participants in Group A received a pre-test,
  familiarization training, and a delayed post-test
  (i.e., post-testing occurred 1 week after
  training). Participants in Group B received a
  pre-test, response feedback training, and a
  delayed post-test. Participants in Group C, the
  control group, received a pre-test, no training,
  and a delayed post-test. Participants in Group D
  received familiarization training, an immediate
  post-test (i.e., post-testing immediately
  followed training), and a delayed post-test.
  Participants in Group E received response
  feedback training, an immediate post-test, and a
  delayed post-test.
• Pre-testing, which occurred for Groups A, B, and
  C, consisted of an initial baseline testing
  session where participants provided word
  identification responses to digitally recorded
  speech samples from 8 children who were oral
  communicators with severe-to-profound hearing
  impairments. The 8 samples consisted of the first
  50 words of a narrative production (story
  telling) elicited from each child the 8 samples
  were selected from a larger pool of samples in
  order to represent a range of intelligibility
  levels. Participants were told that they would be
  listening to children telling stories and that
  they would hear each recording 3 times they were
  instructed to write down all the words they
  understood. Each participant was presented a
  different randomized sequence of the samples.
• Within 1 week of initial testing, participants in
  Groups A and B received training. Participants in
  Group A received familiarization training which
  consisted of listening to 8 training samples 3
  times each while following along with a printed
  transcript of what each child was attempting to
  say. The same children who produced the test
  samples produced the 8 training samples each
  sample consisted of the first 25 words of each
  childs retelling of a different story.
  Participants in Group B received response
  feedback training which involved listening to the
  training samples 3 times each, writing down the
  words that were understood, and receiving
  feedback about which of the words were identified
  correctly. Training sessions for both conditions
  lasted 60 minutes.
• Approximately one week after training conditions
  were completed, all participants in Groups A, B,
  and C were tested again (delayed post-test) under
  conditions identical to those during the
  pre-testing, except that each participant
  responded to a different randomized sequence of
  the samples. Participants transcripts of the
  samples (pre and post training) were scored using
  a scoring key to determine the number of
  correctly identified words. The scoring key
  consisted of transcripts of the 8 samples that
  represented each childs intended words as
  determined by consensus between the speech
  language pathologist who had elicited the
  original samples and the parent of each child.

• Participants in Group D received familiarization
  training and participants in Group E received
  feedback training however, participants in these
  groups did not undergo pre-testing and their
  post-testing occurred immediately after training
  was completed and again one week later (delayed
  post-testing).

• Effects of two methods of training
  (familiarization and feedback) on listeners
  judgments of the intelligibility of speech of
  children with severe to profound hearing
  impairments were examined. Results indicated
  significantly increased intelligibility scores
  across groups and a significant short-term effect
  for feedback training on a word identification
  measure of speech intelligibility.

RESULTS

• Since every group was tested twice, a one-between
  and one-within repeated measures analysis was
  conducted that found all three effects (group,
  testing, testing by group) on word identification
  scores highly significant (See Table 1, Figure 1
  and Table 2). The main effect for the group,
  however, is not very meaningful to interpret in
  this case because it would be averaged across
  different testing times. Only the main effect for
  the testing and testing by group interaction are
  interpreted.

INTRODUCTION

• Several studies have reported that professionals
  who work with deaf and hard of hearing children
  tend to find their speech more understandable
  than do people who are unfamiliar with the speech
  of these children (McGarr, 1983 Monsen, 1983
  Klimacka, 2001). Interestingly, in one study
  (Monsen, 1983) the difference in scores between
  experienced and inexperienced listeners decreased
  somewhat as inexperienced listeners heard more
  examples of hearing impaired speech. Such a
  finding suggests that at least for some
  individuals simply becoming more familiar with
  difficult to understand speech may be an
  important factor in the individual variance noted
  among listeners. Beyond Monsens observation,
  however, there has been little systematic
  investigation of the effect of familiarization,
  or other types of listener training, on
  listeners intelligibility judgments of the
  speech of hearing impaired children.
• The purpose of the present study was to examine
  the effects of two methods of training
  (familiarization and feedback) on listeners
  judgments of the intelligibility of speech of
  children with severe to profound hearing
  impairments. Two different methods were used to
  assess the effects of training (i.e., pre-test
  training delayed post-test and training
  immediate post-test delayed post-test).

• On average, all five groups regardless of the
  type of training improved their word
  identification over time (i.e., from pre to
  immediate post and further to delayed post F 1,
  435 224, plt.0001). Tests of simple main effects
  for the interaction further revealed that Group E
  which received feedback had a significantly
  higher word identification score at immediate
  post-test compared to Groups C, the control group
  (t10.5, plt.05), and B, another group that
  received feedback training (t18.9, plt.0001).
  Group E also outscored Group B at the delayed
  post-test (t11, plt.01). There was no significant
  difference between the average word
  identification scores of Group D (familiarization
  training) at immediate post-test when compared to
  the control group at the pre-test, however.

Figure 1. Graph of the Mean Scores on the Word
Identification Measure As a Function of Training
(Group) and Time of Testing
DISCUSSION

• Overall, results indicate that for the samples
  and listeners in this study, repeated exposure,
  with or without training, leads to improved word
  identification scores. Beyond the effect of
  repeated exposure, listeners judgments of the
  intelligibility of speech appear to increase
  significantly immediately after training in which
  listeners receive feedback regarding the accuracy
  of their word identification responses. Further
  research is currently underway to determine the
  effect of more extensive feedback training on
  word identification scores over time.

METHOD

• Participants
• Fifty-five undergraduate students (M age 20 yr
  SD 4 mos.) from introductory classes in
  communication disorders volunteered to
  participate. None of the listeners reported any
  previous experience listening to, or judging the
  intelligibility of, the speech of children with
  severe-profound hearing impairments. All the
  participants passed screening tests indicating
  speech, language and hearing to be within normal
  limits.