acoustic phonetics 3

8/10/2019 Acoustic Phonetics 3

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ACOUSTIC PHONETICS

Presented by Group 8

Chhay Siv-y Khourn Mithona

Eang Norphealey Tung Chanpollim



SOURCE/FILTER THEORYBy Khourn Mithona



SOURCE/FILTER THEORY

• There are the various overtone pitches that give it its

distinctive quality.

• The overtones are called formants, and the lowest three

formants distinguish vowels from each other.

• Formant : phonetic quality of a vowel



• The lowest formants divided in 3

a. can be heard by tapping on your throat

b. can be heard more easily when these vowels are

whispered.

c. there is no easy way to making it more evident.



HOW DO THESE FORMANTS ARISE?

• The vocal folds: the source of sound energy

• The vocal tract serves as a frequency filter altering the

timber of the vocal fold sounds

• Different lengths and shapes of the vocal tract give

different formants



• Vowels: the whole vocal tract, glottis to lips, is theacoustic filter (ex: resonator)

• Fricatives: from alveolar ridge to lips (ex: [s], [f], [z]…)

• Nasals: extra resonator tube

• Laterals: air flows side-ways



TUBE MODEL

• The formants that characterize different vowels are the

result of the different shapes of the vocal tract.

• The vocal folds vibrate and produce sound

(ex: pluses of acoustic energy)



• The tube can have various shapes and they modify thevocal fold sounds. (ex: resonator)

- depending on the shape, the air will vibrate many

different ways in the vocal tract.

- vowel are the sum of these waveforms added

together.



PERTURBATION THEORYBy Chhay Siv-Y



PERTURBATION THEORY

• According to a formula that even a tube with a uniform

diameter has simultaneous resonance frequencies-

several different pitches at the same time.



• Theses resonance frequencies change in predictable wayswhen the tube is squeezed at various location.

• For example, when the lips are rounded, the diameter of

the vocal tract is smaller at the lips than at other

locations in the vocal tract .



• For each formant, there are location in the tract where

constriction will cause the formant frequency to rise, and

locations where constriction will cause the frequency to fall.

Pressure (P)and velocity (V) maxima in the standing waves

of the first three vowel formants.



ACOUSTIC ANALYSIS

• Phonetic scientists like to describe vowels in term of

number.

• It is possible to analyze sounds so that we can measure

that actual frequencies of the formant.



The frequencies of the first three formantsin eight American English vowels



ACOUSTICS OF CONSONANTS

By Tung Chanpollim



• Figure 8.7 Spectrograms of bed, dead, and [ɡɛɡ].



All this three words, the first formant rise from a low

position. This is simply a mark of a stop closure and does

not part in distinguishing one place of articulation from

another.



Figure 8.8Spectrogram of the forms [pʰɛm],[tʰɛn], and [kʰɛŋ]



• The burst for[p] has the lowest frequency. For both [t]

and [k], the noise extends above the 400 Hz shown in

the spectrogram. The highest frequencies are actually in

the [t] burst rather then the [k] and the lowest with[p].



Figure 8.9Spectrogram of "fie, thigh, sigh, shy"



Figure 8.10A spectrogram of ever, weather, fizzer, pleasure.



Figure 8.11A spectrogram of led, red, wed, yell



INTERPRETING SPECTROGRAMSBy Eang Norphealey



INTERPRETING SPECTROGRAMS• What is a spectrogram?

is a graphic representation of sounds.



SHE JUST HAD A BABY

• Note that vowels all have regular amplitude peaks

• Stop consonant

• Notice the silence followed by slight bursts of emphasis: very clear for[b] of “baby ”



INTONATIONAL TUNES



YES-NO QUESTION TUNE

are LEGUMES a good source of vitamins

Rise from the main accent to the end of the sentence.




are legumes a GOOD source of vitamins





are legumes a good source of VITAMINS




WH-QUESTIONS

WHAT are a good source of vitamins

WH-questions typically have falling contours, like statements.

[I know that many natural foods are healthy, but ...]



BROAD FOCUS

legumes are a good source of vitamins

“Tell me something about the world.”

In the absence of narrow focus, English tends to mark the firstand last ‘content’ words with perceptually prominent accents.



RISING STATEMENTS

legumes are a good source of vitamins

High-rising statements can signal that the speaker is seeking approval.

“Tell me something I didn’t already know.”

[... does this statement qualify?]



YES-NO QUESTION

are legumes a good source of VITAMINS




USING INTONATION IN SPOKENLANGUAGE PROCESSING

1) Prominence/Accent: Tells us about focus of utterance

2) Tune: whether utterance is question/statement,

important for affect extraction

3) Boundaries: can help parsing



THANK YOU FOR YOUR

ATTENTION!

acoustic phonetics 3

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