Identification of prosodic near- minimal Pairs in Spontaneous Speech Keesha Joseph Howard University Center for Spoken Language Understanding (CSLU) Oregon Health & Science University (OHSU) Portland, Oregon, USA August 10, 2010

 Background Information  Research Questions  Data and Subjects  Research Activities  Conclusion and Future Work  Questions? Agenda

 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  vs Background Information

 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? Research Questions

 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 Data and Subjects

 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.  C = Consonant  V = Vowel  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.

 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. Research Activities

Consonant Phoneme Class and Vowel Phoneme Pairs SubjectWords Potential NMP Time(hours)Actual NMP Actual NMP / Potential NMP # of Actual NMP found in an hour OGI %2.7 OGI %1.5 OGI %.4 OGI %1.0 OGI %1.0 OGI %1.2 OGI %1.3 OGI %1.6 OGI %2.0

 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  Research Activities

Type of Pairs # of Potential Near Minimal Pairs Exact390 Phoneme Class / Individual Vowels (27)397 Vowel Class: Height (5)423 Vowel Class: Backness(5)428 Vowel Class: Length(3)531 All Pairs for OGI-082

 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 to see if the results found in that paper are also in spontaneous speech. Conclusion and Future Work

 Emily Tucker Prud’hommeaux  Jan van Santen  CSLU Staff and Interns Thanks for making this an experience I wont forget! THANKS!

Questions?