ACOUSTICPHONETIC CHARACTERISTICS OF LENGTHENING IN STUTTERING AND NONSTUTTERING SPEECH

1
ACOUSTIC-PHONETIC CHARACTERISTICS OF LENGTHENING
IN STUTTERING AND NON-STUTTERING SPEECH

• Bóna, Judit PhD
• assistant lecturer
• Eötvös Loránd University, Department of Phonetics
• H-1088 Budapest, Múzeum krt. 4/A, Hungary
• bona_judit_at_freemail.hu

ABSTRACT The aim of this paper is to define the
criteria when lengthening as a disfluency would
be considered as non-typical. Spontaneous speech
of Hungarian adult stutterers was acoustically
analysed and compared to that of control
speakers. Our hypothesis is that there are
differences concerning the durations and
occurrences of lengthened speech sounds between
stutterers and non-stutterers.
2

• HYPOTHESIS
• Our hypothesis is that there are differences
  concerning the speech sound durations and
  occurrences of lengthening in the stutterers and
  non-stutterers speech.
• SUBJECTS, METHOD, MATERIAL
• 3 stutterers (1 serious, 2 mild ones ages
  between 21 and 32) and 3 non-stutterers (ages
  between 21 and 23). 1 female, 2 males in each
  group.
• 5-minute spontaneous speech of all subjects was
  recorded
• Data 173 cases of lengthenings and 380 typically
  pronounced speech sounds
• Analysis Praat 5.0 and SPSS 13.0

• INTRODUCTION
• One of the most characteristic symptoms of
  stuttering is the fitful lengthening of the
  initial speech sounds of the words. The
  occurrence and the phonetic properties of
  lengthening seem to be speaker-dependent.
  However, the lengthening is a phenomenon that can
  be found frequently in non-stuttering speech as
  well.
• In Hungarian spontaneous speech lengthening can
  be spotted mostly with vowels frequently on
  definite articles (a and az). The perception of
  lengthening depends on various factors including
  actual duration of the speech sound.
• However, there is little information about the
  acoustic-phonetic properties of lengthening in
  spontaneous speech of stutterers.

3
Ratio of durations of lengthened sounds compared
to normal ones () Lengthened duration values
divided by average values of duration.
Duration of lengthened speech sounds
st stutterers nst non-stutterers f
females m males
4
THE LENGHTENINGS OF THE SERIOUS STUTTERERS
F (1,115) 12,785 p 0.001
60 of lengthened sounds were accompanied by
turbulent noise (the more serious the stuttering
the more frequently appeared).
5
OCCURRENCES

• Normal subjects
• Frequency 1 to 1.2 lengthenings per 100 words

• Stutterers
• Frequency 4.5 to 42 lengthenings per 100 words

55 of the lengthened sounds occurred on the
first sound of the word.
6
CONCLUSIONS

• The absolute duration of lengthening is longer
  with serious stutterers than with those of mild
  stutterers and non-stutterers. Lengthening is (i)
  frequently longer than 1 sec and (ii) accompanied
  by turbulent noise with serious stutterers.
• The consonants are more frequently lengthened
  than the vowels by the stutterers. The control
  speakers show the tendency to lengthen the
  vowels.
• There is no difference in the durations of
  lengthenings between mild stutterers and the
  control speakers.
• There are differences, however, in the phenomenon
  of lengthenings between mild stutterers and
  non-stutterers concerning
• their frequency,
• the type of the lengthened sounds, and
• the word categories where they occur.
• The form of occurrence of lengthening seems to be
  definitive in early identification of stuttering.