Phonetics & Phonology by 0Y6002e

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									Phonetics & Phonology

      William Barry
         What is phonetics
• The observation of how people say things.
• The description of spoken language at
  the level of "pronunciation"
• The measurement of pronunciation events
• The modeling of pronunciation behaviour
• The explanation of the communicative
  contribution of pronunciation patterns.
         Areas of phonetics
• Speech production
 (what do the speech organs do?)

• Speech acoustics
 (what does the resulting speech signal look like?)

• Speech perception
 (What are the acoustic properties that cause us
 to hear what we hear?)
    Speech production [levels]
• Respiration (sub-glottal activity)
  How do we control our breathing to help our
  speech communication?
• Phonation (glottal/laryngeal activity)
  How do we control our vocal-folds to help our
  speech communication?
• Articulation (supra-glottal activity)
  How do we control our articulators to help our
  speech communication?
    Speech production [analysis]
• We make recordings (of course  )
 - we choose the type of speech
 - we choose the type of speaker
 - we choose the type of signal

• These choices determine our analysis:
 - speech type (basic sound types, precise vs. casual speech;
   monologue vs. dialogue behaviour)
 - speaker type (e.g., regional vs."standard" speakers; ……)
 - signal type (acoustic = microphone; physiological; electro-
 myographic; neurological .......)

• Signal type dictates the experimental set-up:
 - Only the acoustic signal allows „natural" recordings
          A standard text .....
  The North Wind and the Sun
  The North Wind and the Sun were disputing which was the
  stronger, when a traveler came along wrapped in a warm
  cloak.
  They agreed that the one who first succeeded in making the
  traveler take his cloak off should be considered stronger
  than the other.
  Then the North Wind blew as hard as he could, but the
  more he blew the more closely did the traveler fold his cloak
  around him; and at last the North Wind gave up the attempt.
  Then the Sun shined out warmly, and immediately the
  traveler took off his cloak. And so the North Wind was
  obliged to confess that the Sun was the stronger of the two.
(see www.coli.uni-saarland.de/elaut for other languages)
             For signal analysis
Popular analysis packages:
• Praat (www.praat.org)
  (by Paul Boersma & David Weenink, Phonetics Amsterdam)
• Wavesurfer (www.speech.kth.se/wavesurfer/)
  (by scientists at Stokholm Technical University - KTH)
• Goldwave (www.goldwave.de)
  (commercial program, but available free for trial use)
Speech production [Speech Sounds]
E.g. What are the vowels of English and
  German like?
• The cat sat on the mat:
 SBE: ??;     US: ??    German: ??
• The computer is broken.
  SBE: ??;    US: ??    German: ??
• Can you hear the differences?
• Can you describe the differences?
• Can you say why there are differences?
        Vowel quality and symbols
        German                               English
iy                     u
                              ?i                 u
 I Y                 U          I
                                                   U
e O                   o    eI

                              ?e                  U
                                                / Br 
 (E)                                           /
                               (E)            Br US
  E                     
                                   US
                                                       ?    US   
                                    
                                                             Br 
                                    Br                  US
            a/a                                           A A
Speech production [Speech Sounds]
E.g. What are the consonants of English and
  German like?
• The cat sat on the mat:
 SBE: ??;     US: ??    German: ??
• The computer is broken.
  SBE: ??;    US: ??    German: ??
• Can you hear the differences?
• Can you describe the differences?
• Can you say why there are differences?
Speech production [symbols & sounds]
               Consonant articulation
 • Place                         • Manner
   – lips (labial)                 – stop/plosive
   – teeth (dental)                – fricative
   – alveolar ridge (alveolar)     – nasal
   – hard palate (palatal)         – lateral
   – soft palate (velar)           – glide/approximant
   – uvula (uvular)                – trill
   – pharynx (pharyngeal)          – tap/flap
   – larynx/glottis (glottal)
Speech production [symbols again]
• IPA table
   Speech production [Intonation]
(Intonation can have a syntactic or pragmatic function)
Statement – Question (sentence modality)
• Scotland beat France at rugby.
• Scotland beats France at rugby?


Request – Command (pragmatic function)
• Could you come to my office?
• Could you come to my office?
      So what‘s "Phonology“?
• The systematic use of sound segments and
  prosody in a specific language
• Examples:
  – German has vowels a, b, c, d, f .....
    English has a, c, e, .....
  – German has final devoicing of obstruents
  – The 'voicing' of English plural & genitive {s} and past
    tense {d} follows the preceding sound
  – Stress falls on the first element in compound words in
    German (in English the second element is often
    stressed) – Compare English vs. German:
    (Eng.) Buckingham Palace, Albert Hall, National
    Gallery
              and Perception?
• Interesting facts:
  We don‘t identify the individual sounds as they reach our
  ears.
  The syllable: (cons) + vowel + (cons) is probably the
  smallest unit of perception.
  The consonants by themselves contribute less than the
  vowels by themselves to our understanding of a spoken
  utterance.
  (but they contribute more to the understanding of an
  utterance if there is one unchanging vowel than the
  vowels do with one unchanging consonant!)
And what about written consonants and vowels?
  Consonants vs. vowels [1]
__e _ea_e_ _o_e_a__ _o_ _o_o__o_:
_a__e_ __ou_y i_ __e _o__i__ _i__
a _e_ _u__y __e___ i_ __e
a__e__oo_.
 Consonants vs. vowels [2]
Th_ w _th_r f_r_c_st f_r t_m_rr_w:
r_th_r cl __d_ _n th_ m_rn_ng w_th _
f_w s_nn_ sp_lls _n th_ _ft_rn__n.
    Consonants vs. vowels [3]
• The weather forecast for tommorow: rather
  cloudy in the morning with a few sunny
  spells in the afternoon.
    Consonants vs. vowels [4]
• The weather forecast for tommorow: rather
  cloudy in the morning with a few sunny
  spells in the afternoon.

• speech versions
  – only consonants
  – only vowels
  – original
    Consonants vs. vowels [5]
• The vowel information is greater, but we need the
  temporal pattern (the rhythm) of the utterance
  (a product of the syllable structure (cons+ vowels)
  and the duration/weight/prominance of the vowels.

• only vowels – without silences
• only vowels – with silences
• only vowels – monotonous
     So we perceive in chunks
• The syllables are the (more prominent) vowels
  with the (less prominent) consonants around
  them
• The sentences are the chains of syllables,
  with the more prominent words (the lexical or
  content words) giving the content and the less
  prominent words (grammatical or function
  words) grouped around them, showing the
  relation between them
• The melody (intonation pattern) helps to make
  the important words more prominent.
         Connected speech
"The president will be elected for a period of
  four years."
• Natural connected speech
• as chain of isolated words (no reductions)
• Natural with silences between words
• as chain of isolated without silences
• Comparison of isolated vs. connected
  function words
    Connected speech (summary)
"The president will be elected for a period of four years."
• The content words are longer, louder,
  unreduced, comprehensible when excised.
• The grammatical words are shorter, less
  loud, strongly reduced, incomprehensible
  when excised.
• The “production effort“ we invest reflects the importance
  of the words (longer + louder + unreduced = more care
  and effort).
• Our perception strategies follow this unequal distribution
  of effort. We concentrate on the prominent words.
  (BUT: Careful! This is a strategy associated with certain
  types of languages “stress-timed languages“.
  Not all languages do this. So-called “syllable-timed
  languages“ are less stress oriented.)
So, what applications are there?
We don‘t normally think about pronunciation. for
granted, so understanding the mechanisms of
speech is invaluable in
• foreign language teaching/learning
• pronunciation dictionaries
• speech pathology
• forensic phonetics
• speech technology
Let‘s look briefly at speech synthesis
Commercial systems use "concatenative" methods
(they stick recorded bits of speech together)
• They don‘t need very much phonetic knowledge (but they need to have
 good selection strategies) and the same approach can be applied to
 many different languages.
• The systems are good in limited domains, and using a neutral
 speaking style. They are bad on wide-ranging topics and more
 expressive speech.
Research systems, such as "articulatory synthesis"
require a lot of knowledge, and are used to find out more
about speech production.
• They are potentially very flexible (so the developer has to know how
  to constrain the system just to produce what is natural)
• They are much more complex, and have to be programmed for each
  new language on the basis of knowledge acquired about that language.
            Speech synthesis
A locally developed product (and research platform):
•"Mary": http://mary.dfki.de

Now a (staged) example of how unexpressive
synthesis in an inflexible dialogue system can go
wrong (German railway timetable inquiry system):
•Synthesis + Recognition = Dialogue?
(or chaos?)

								
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