Identification of prosodic nearminimal Pairs in Spontaneous
Speech
Keesha Joseph
Howard University
Center for Spoken Language Understanding (CSLU)
Oregon Health & Science University (OHSU)
Portland, Oregon, USA
josephk@cslu.ogi.edu
August 10, 2010
Agenda
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Background Information
Research Questions
Data and Subjects
Research Activities
Conclusion and Future Work
Questions?
Background Information
 van Santen et al. 2009/2010
 Very structured tasks tested a child’s ability to make
distinctions in focus and stress
 Video Time!!
 Some acoustic features were different in Autism Spectrum
Disorder (ASD) versus Typically Developing (TD) subjects
 Problem:
 Tasks situation is structured and artificial.
 Would we find the same outcome in spontaneous speech?
Background Information
 The tasks used prosodic minimal pairs.
 A prosodic minimal pair is a 2-syllable phrase with the same
phoneme sequence but the stress is on a different part of the
phrase.
 blue COW vs BLUE cow
 A near minimal pair has similar (but not identical) phonetic
content where the phoneme classes are the same but the
phonemes might not be.
 Different Phrases:
 my dad vs my bag
 Same phoneme classes and vowels but different phonemes
 nas_aI_vst_@_vst vs
nas_aI_vst_@_vst
Research Questions
 Can we find minimal pairs in spontaneous speech?
 Can we find near minimal pairs if there are not many
minimal pairs found in spontaneous speech?
 How do we find near minimal and minimal pairs?
 How can we evaluate whether our method of finding
minimal pairs works?
Data and Subjects
 5 kids with Autism Spectrum Disorder and 5 kids with
Typical Development
 Transcripts of ADOS diagnostic interviews were used
as examples of spontaneous speech
 Festival Speech Synthesis software was used to
convert the ADOS interview transcripts to phonetic
transcriptions
Research Activities
 Changed consonants in a string of phonemes to their
respective phoneme class
 (Unvoiced Stops, Voiced Stops, Unvoiced Fricatives,
Voiced Fricatives, Affricates, Liquids, Nasals, Glides)
 This process finds near minimal pairs
 Example: ufr_>_liq_ufr_3r_vst could either be
f_>_9r_T_3r_d (four thirt|y) or
f_>_9r_f_3r_g (for forg|et)
Research Activities
1. Create a script to find phonetic strings the follow a CVC+VC
pattern.
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C = Consonant
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V = Vowel
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C+ = Consonant
2. Create a file for each subject with all possible phonetic strings
that follow a CVC+VC pattern.
3. Sort on phonetic strings to find groups of potential near minimal
pairs.
 These phonetic strings are called potential near minimal pairs
4. Manually searched through potential near minimal pairs to find
actual near minimal pairs.
Research Activities
 Use Praat to listen to sentences of the ADOS to find actual
near minimal pairs.
 Rule out criteria:
 The interviewer was speaking over that potential minimal pair
 The kid was making a lot of noise (i.e. hitting the table while
speaking)
 The kid was whispering or not close enough to the
microphone
 A Potential Near Minimal Pair is an Actual Near Minimal
Pair only if:
 The items of the pair have a contrasting stress pattern.
Consonant Phoneme Class and Vowel
Phoneme Pairs
Actual NMP
Actual NMP
/ Potential
NMP
# of Actual
NMP found
in an hour
Subject
Words
Potential
NMP
OGI-007
1471
518
1.5
4
.77%
2.7
OGI-013
1324
426
2
3
.70%
1.5
OGI-016
2242
667
2.5
1
.15%
.4
OGI-027
2166
789
2
2
.25%
1.0
OGI-033
3427
1531
4
4
.26%
1.0
OGI-042
2305
896
2.5
3
.33%
1.2
OGI-064
1308
1042
1.5
2
.19%
1.3
OGI-065
2115
744
2.5
4
.54%
1.6
OGI-082
1203
397
1.5
3
.76%
2.0
Time(hours)
Research Activities
 We decided to collapse vowels into classes to find more
potential near minimal pairs
 For example my_dad under these vowel classes:
 Height
 nas_diph_vst_low_vst
 Backness
 nas_diph_vst_front_vst
 Length
 nas_long_vst_short_vst
 For comparison, also looked at exact phonemes for minimal
pairs
 m_aI_d_@_d
All Pairs for OGI-082
Type of Pairs
# of Potential Near
Minimal Pairs
Exact
390
Phoneme Class / Individual Vowels (27)
397
Vowel Class: Height (5)
423
Vowel Class: Backness(5)
428
Vowel Class: Length(3)
531
Conclusion and Future Work
 Surprisingly small number of potential NMPs even with
broad phoneme classes.
 This method for finding near minimal pairs is feasible with
well trained annotator.
 The length of time it took to find such pairs decreased with
experience
 Future Work
 Further broadening of phoneme classes.
 Alignment of phonemes to waves for these pairs.
 Run the analysis of van Santen et al. 2010 to see if the results
found in that paper are also in spontaneous speech.
THANKS!
 Emily Tucker Prud’hommeaux
 Jan van Santen
 CSLU Staff and Interns
Thanks for making this an experience I wont forget!
Questions?