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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 l.jpg

Spectrogram & its reading

by Tae-Yeoub Jang


What is spectrogram l.jpg
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

Reviving Sonus



Spectrogram example grayscale of word compute l.jpg
Spectrogram example (grayscale of word “compute”)

Reviving Sonus


Slide5 l.jpg

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

Reviving Sonus


Types of spectrogram l.jpg
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

Reviving Sonus


Advantages disadvantages l.jpg
Advantages & Disadvantages

  • Advantages

    • Time alignment

  • Disadvantages

    • Less reliable than waveform

Reviving Sonus


Vowel spectrogram l.jpg
Vowel Spectrogram

  • Formant frequencies are critical cues for vowel distinction

  • F1: Height

    • high vowels: low F1

  • F2: Backness

    • back vowels: low F2

Reviving Sonus



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

Reviving Sonus


Consonant spectrogram l.jpg
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

Reviving Sonus


What is locus l.jpg
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

Reviving Sonus


Stops l.jpg
Stops

  • General

    • Fairly distinct locus for each place

    • Burst

    • Silence during the closure (only at syllable onset position)

    • Virtually no difference during the closure

Reviving Sonus


Stops cntd l.jpg
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

Reviving Sonus


Stops cntd15 l.jpg
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

Reviving Sonus


Stops cntd16 l.jpg
Stops (cntd.)

  • Manner distinction

    • Silence duration, VOT, vowel F0

Reviving Sonus


Examples a bab a dad a gag l.jpg
Examples -- “a bab, a dad, a gag”

Reviving Sonus


Place dependent loci l.jpg
Place dependent loci

Reviving Sonus


Fricatives l.jpg
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 l.jpg
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

Reviving Sonus


Example fie thigh sigh shy l.jpg
Example –“fie, thigh, sigh, shy”

Reviving Sonus


Example ever weather fizzer pleasure l.jpg
Example –“ever, weather, fizzer, pleasure”

Reviving Sonus


Nasals l.jpg
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

Reviving Sonus


Examples a pam a tan a kang l.jpg
Examples -- “a Pam, a tan, a kang”

Reviving Sonus


Liquies approximants l.jpg
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

Reviving Sonus


Liquids approximants cntd l.jpg
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

Reviving Sonus


Liquids approximants cntd27 l.jpg
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

Reviving Sonus


Example led red wed yell l.jpg
Example –“led, red, wed, yell”

Reviving Sonus


Final remarks l.jpg
Final remarks

  • Spectrogram is not the only cue for acoustic distinction of speech sounds

  • Very often, the waveform is more reliable

Reviving Sonus


References links l.jpg
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

Reviving Sonus


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