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Spectrogram & its reading. by Tae-Yeoub Jang. What is spectrogram?. Begin to be used since 1940s Another representation of frequency domain analysis The most popular way of representing spectral information 3 dimensional representation X-axis: Time Y-axis: Frequency

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spectrogram its reading

Spectrogram & its reading

by Tae-Yeoub Jang

what is spectrogram
What is spectrogram?
  • Begin to be used since 1940s
  • Another representation of frequency domain analysis
  • The most popular way of representing spectral information
  • 3 dimensional representation
    • X-axis: Time
    • Y-axis: Frequency
    • Darkness (or color): Energy

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Wideband vs. Narrowbandspectrograms of the question "Is Pat sad, or mad?" The 5th, 10th and 15th harmonics have been marked by white squares in two of the vowels

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types of spectrogram
Types of spectrogram
  • Wideband spectrogram
    • better time resolution
    • eg) 15 msec window, 1 msec shift, 125 Hz bandwidth
  • Narrowband spectrogram
    • better frequency resolution
    • eg) 50 msec window, 1 msec shift, 40 Hz bandwidth

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advantages disadvantages
Advantages & Disadvantages
  • Advantages
    • Time alignment
  • Disadvantages
    • Less reliable than waveform

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vowel spectrogram
Vowel Spectrogram
  • Formant frequencies are critical cues for vowel distinction
  • F1: Height
    • high vowels: low F1
  • F2: Backness
    • back vowels: low F2

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heed hid head had hod hawed hood who d a male speaker american english
"heed, hid, head, had, hod, hawed, hood, who\'d" (a male speaker, American English)

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consonant spectrogram
Consonant Spectrogram
  • General
    • Acoustic structure more complicated than vowels
    • Adjacent sounds (especially vowels) convey important information  locus
    • High frequency characteristics

 especially for fricatives and affricates

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what is locus
What is LOCUS
  • Information of formant transition from vowels into obstruents or from obstruents into vowels
  • The target frequency that each formant transition is heading toward as an obstruction is made, or the frequency the transition comes as the obstruction is released
  • The characteristic of the consonantal place and manner  roughly the same in different vowel contexts

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stops
Stops
  • General
    • Fairly distinct locus for each place
    • Burst
    • Silence during the closure (only at syllable onset position)
    • Virtually no difference during the closure

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stops cntd
Stops (cntd.)
  • Voicing distinction
    • voiced: vertical striations for voiced sounds, less abrupt burst, frequently weakened to be like fricatives or approximants
    • voiceless: generally abrupt burst at higher frequency area

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stops cntd15
Stops (cntd.)
  • Place distinction
    • bilabial
      • relatively low F2, F3 locus  rising into and falling out of vowel
      • weak and spread vertical lines
    • alveolar
      • F2 locus about 1800 Hz
      • Strong vertical lines
    • velar
      • Velar pinch: vowels F2, F3 merging
      • often double burst
      • long formant transitions

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stops cntd16
Stops (cntd.)
  • Manner distinction
    • Silence duration, VOT, vowel F0

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place dependent loci
Place dependent loci

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fricatives
Fricatives
  • General
    • Random noise pattern especially in high frequency regions
    • Place distinction
      • Labiodental [f, v]: rising locus into the following vowel
      • Dental [, ð]: major energy above 6000Hz
      • Alveolar [s, z]: major energy above 4000Hz
      • Alveopalatal [š, ž ]: major energy above 6000Hz
      • Glottal [h]: the trace of formant frequencies of neighbouring vowels

Reviving Sonus

fricatives cntd
Fricatives (cntd.)
  • Weak vs. strong
    • Strong [s, z, š, ž ]: darker bands
    • Weak [f, v, , ð ]: spread and fainter
      • Voiced [v, ð ]: often so weak and confused with nasals or approximants
      • Cues to tell [] from [f]: higher formants of [] fall into adjacent vowels

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nasals
Nasals
  • General
    • Formants similar to vowels but fainter
    • Very low F1 (about 250Hz), F2 (about 2500Hz), and F3 (about 3250Hz)
  • Place distinction
    • bilabial [m]: downward F2, F3 locus
    • alveolar [n]: less amount of F2 transition
    • velar [ŋ ]: velar pinch

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liquies approximants
Liquies & Approximants
  • General
    • Formants similar to vowels but fainter (especially at high frequency regions)
    • Approximately F1(250Hz), F2(1200Hz), F3(2400Hz)
    • Change in formant structure

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liquids approximants cntd
Liquids & Approximants(cntd.)
  • Phone specific properties
    • Labial glide [w]:
      • very low F1, F2 (600-1000Hz|) and gets too close to each
      • relatively low F3
      • rapid falloff of spectral amplitude
    • Palatal glide [y]:
      • extremely low F1
      • extremely high F2, F3

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liquids approximants cntd27
Liquids & Approximants(cntd.)
  • Phone specific properties (cntd.)
    • Flap [Ր]: soft burst, short duration
    • Retroflex [r]:
      • F3 dipping down close to F2
      • General lowering of F3, F4
    • Lateral [l]:
      • Low F1, F2 (approx. F1 250Hz, F2 1200Hz)
      • usually substantial energy in the high F region

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final remarks
Final remarks
  • Spectrogram is not the only cue for acoustic distinction of speech sounds
  • Very often, the waveform is more reliable

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references links
References & Links
  • http://cslu.cse.ogi.edu/tutordemos/SpectrogramReading/spectrogram_reading.html
  • http://hctv.humnet.ucla.edu/departments/linguistics/VowelsandConsonants/course
  • http://www.cs.indiana.edu/~port/teach/306/speech.acoustics.html
  • http://www.phon.ucl.ac.uk/courses/spsci/b203/week2-5.pdf

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