Ch2-Speech_Sounds_of_US_English

Ch2-Speech_Sounds_of_US_English - Speech Recognition Speech...

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Unformatted text preview: Speech Recognition Speech Sounds of American English Speech Sounds of American English There are over 40 speech sounds in American English which can be organized by their basic manner of production Manner Class Number Vowel Fricatives Stops Nasals Semivowels Affricates Aspirant 18 8 6 3 4 2 1 Vowels, glides, and consonants differ in degree of constriction Sonorant consonants have no pressure build up at constriction Nasal consonants have no pressure build up at constriction Continuant consonant do not block airflow in oral cavity February 13, 2012 Veton Kpuska 2 Phonemes of American English February 13, 2012 Veton Kpuska 3 Phonetic Alphabets Reference February 13, 2012 Veton Kpuska 4 Vowel Production No significant constriction in the vocal tract Usually produced with periodic excitation Acoustic characteristics depend on the position of the jaw, tongue, and lips February 13, 2012 Veton Kpuska 5 Vowels of American English There are approximately 18 vowels in American English made up of monothongs, diphthongs, and reduced vowels (schwa's) They are often described by the articulatory features: High/Low, Front/Back, Retroflexed, Rounded, and Tense/Lax February 13, 2012 Veton Kpuska 6 Spectrograms of the Cardinal Vowels February 13, 2012 Veton Kpuska 7 Vowel Formant Averages Vowels are often characterized by the lower three formants: High/Low is correlated with the first formant, F1 Front/Back is correlated with the second formant, F2 Retroflexion is marked by a low third formant, F3 February 13, 2012 Veton Kpuska 8 Vowel Durations Each vowel has a different intrinsic duration Schwa's have distinctly shorter durations (50ms) /I, , , / are the shortest monothongs Context can greatly influence vowel duration February 13, 2012 Veton Kpuska 9 Happy Little Vowel Chart "So inaccurate, yet so useful." February 13, 2012 Veton Kpuska 10 Fricative Production Turbulence produced at narrow constriction Constriction position determines acoustic characteristics Can be produced with periodic excitation February 13, 2012 Veton Kpuska 11 Fricatives of American English There are 8 fricatives in American English Four places of articulation: LabioDental (Labial), Interdental (Dental), Alveolar, and PalatoAlveolar (Palatal) They are often described by the features Voiced/Unvoiced, or Strident/NonStrident (constriction behind alveolar ridge) February 13, 2012 Veton Kpuska 12 Spectrograms of Unvoiced Fricatives February 13, 2012 Veton Kpuska 13 Fricative Energy Strident fricatives tend to be stronger than nonstrident fricatives. February 13, 2012 Veton Kpuska 14 Fricative Durations Voiced fricatives tend to be shorter than unvoiced fricatives. February 13, 2012 Veton Kpuska 15 Examples of Fricative Voicing Contrast February 13, 2012 Veton Kpuska 16 Friendly Little Consonant Chart "Somewhat more accurate, yet somewhat less useful." February 13, 2012 Veton Kpuska 17 What is this word? February 13, 2012 Veton Kpuska 18 Stop Production Complete closure in the vocal tract, pressure build up Sudden release of the constriction, turbulence noise Can have periodic excitation during closure February 13, 2012 Veton Kpuska 19 Stops of American English There are 6 stop consonants in American English Three places of articulation: Labial, Alveolar, and Velar Each place of articulation has a voiced and unvoiced stop Unvoiced stops are typically aspirated Voiced stops usually exhibit a "voicebar'' during closure Information about formant transitions and release useful for classification February 13, 2012 Veton Kpuska 20 Spectrograms of Unvoiced Stops February 13, 2012 Veton Kpuska 21 Examples of Stop Voicing Contrast February 13, 2012 Veton Kpuska 22 Singleton Stop Durations February 13, 2012 Veton Kpuska 23 Voicing Cues for Stops February 13, 2012 Veton Kpuska 24 /s/Stop Durations February 13, 2012 Veton Kpuska 25 Examples of Front and Back Velars February 13, 2012 Veton Kpuska 26 What is this word? February 13, 2012 Veton Kpuska 27 Nasal Production Velum lowering results in airflow through nasal cavity Consonants produced with closure in oral cavity Nasal murmurs have similar spectral characteristics February 13, 2012 Veton Kpuska 28 Nasal of American English Three places of articulation: Labial, Alveolar, and Velar Nasal consonants are always attached to a vowel, though can form an entire syllable in unstressed environments ([n], [m], ) // is always postvocalic in English Place identified by neighboring formant transitions February 13, 2012 Veton Kpuska 29 Spectrograms of Nasals February 13, 2012 Veton Kpuska 30 What is this word? February 13, 2012 Veton Kpuska 31 Semivowel Production Constriction in vocal tract, no turbulence Slower articulatory motion than other consonants Laterals form complete closure with tongue tip, airflow via sides of constriction February 13, 2012 Veton Kpuska 32 Semivowels of American English There are 4 semivowels in American English Sometimes referred to as Liquids or Glides Glides are a more extreme articulation of a corresponding vowel Semivowels are always attached to a vowel, though /l/ can form an entire syllable in unstressed environments ([l]) February 13, 2012 Veton Kpuska 33 Similar, though more extreme, formant positions Generally weaker due to narrower constriction Spectrograms of Semivowels February 13, 2012 Veton Kpuska 34 Acoustic Properties of Semivowels /w/ and /l/ are the most confusable semivowels /w/ is characterized by a very low F1, F2 Typically a rapid spectral fallo above F2 /l/ is characterized by a low F1 and F2 Often presence of high frequency energy Postvocalic /l/ characterized by minimal spectral discontinuity, gradual motion of formants /y/ is characterized by very low F1, very high F2 /y/ only occurs in a syllable onset position (i.e., prevocalic) /r/ is characterized by a very low F3 Prevocalic F3 < medial F3 < postvocalic F3 February 13, 2012 Veton Kpuska 35 What is this word? February 13, 2012 Veton Kpuska 36 Affricate Production There are two affricates in American English: Alveolarstop palatalfricative pairs Sudden release of the constriction, turbulence noise Can have periodic excitation during closure February 13, 2012 Veton Kpuska 37 Aspirant Production There is one aspirant in American English: /h/ (e.g., "hat'') Produced by generating turbulence excitation at glottis No constriction in the vocal tract, normal formant excitation Subglottal coupling results in little energy in F1 region Periodic excitation can be present in medial position February 13, 2012 Veton Kpuska 38 Spectrograms of Affricates and Aspirant February 13, 2012 Veton Kpuska 39 What is this word? February 13, 2012 Veton Kpuska 40 Phonotactic Constraints Phonotactics is the study of allowable sound sequences Analyses of wordinitial and final clusters reveal: Can be used to eliminate impossible phoneme sequences: /tk/ can't end a word, and /kt/ can't begin a word, Therefore, */... t k t .../ is an impossible sequence 73 distinct initial clusters (about 10 "foreign'' clusters) 208 distinct final clusters February 13, 2012 Veton Kpuska 41 WordInitial Consonants from MWP Dictionary February 13, 2012 Veton Kpuska 42 The Syllable Syllable structure captures many useful generalizations Phoneme realization often depends on syllabification Many phonological rules depend on syllable structure Syllable structure is predicated on the notion of ranking the speech sounds in terms of their sonority values February 13, 2012 Veton Kpuska 43 Syllables and Sonority Utterances can be divided into syllables The number of syllables equals the number of sonority peaks Within any syllable, there is a segment constituting a sonority peak that is preceded and/or followed by a sequence of segments with progressively decreasing sonority values February 13, 2012 Veton Kpuska 44 The Syllable Template Branches marked by "o" are optional Nucleus must contain a nonobstruent Sonority decreases away from nucleus Affix contains only coronals: Only the last syllable in a word can have an affix /sp/, /st/, and /sk/ are treated as single obstruents Veton Kpuska 45 February 13, 2012 Some Examples February 13, 2012 Veton Kpuska 46 Words Containing /r/ and /l/ February 13, 2012 Veton Kpuska 47 Acoustic Realizations of /r/ February 13, 2012 Veton Kpuska 48 Acoustic Realizations of /l/ February 13, 2012 Veton Kpuska 49 Allophonic Variations at Syllable Boundaries February 13, 2012 Veton Kpuska 50 References 1. 2. "Acoustics of American English Speech A Dynamic Approach", J. Olive, A. Greenwood, and J. Coleman, Springer Verlag 1993. "ArticulatoryAcousticAuditory Relationships", Kenneth Stevens, in The Handbook of Phonetic Sciences, Ed. William Hardcastle and John Laver, Blackwell Publishers, 1997. February 13, 2012 Veton Kpuska 51 ...
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This note was uploaded on 02/11/2012 for the course ECE 5526 taught by Professor Staff during the Summer '09 term at FIT.

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