Fricatives + Voice Onset Time

March 31, 2014

In the Year 2000• Today: we’ll wrap up fricatives…

• and then move on to stops.

• This Friday, there will be one final transcription exercise.

• On Bengali, Quebecois French, and Arabic.

• I just posted it right before class.

Acoustic Enhancement• Note: is post-alveolar and [s] is alveolar

• more space in vocal tract in front of

• including a “sub-lingual cavity”

• This “filter” of resonates at lower frequencies

• In English, this acoustic distinction is enhanced through lip rounding for

• this extends the vocal tract

• further lowers the resonant frequencies of

The Sub-lingual Cavity

•Let’s check the videotape...

Behind the Constriction

[s]

• Let’s check the ultrasound…

Other Examples• Susie and David say “speech”:

• Also: Where the shtreets have no name

• And: Tina Fey

• Note: there are no word-initial /sr/ sequences in English.

• “shriek” *“sreek”

Polish• Note: lip-rounding can be used to enhance other fricative contrasts

• In Polish, it enhances the contrast between (post-)alveolar and dental fricatives

• the (post-)alveolars have the rounding

Polish, continued• Polish also has what are known as alveolo-palatal fricatives.

• = constriction in the post-alveolar region

• + raised tongue in the palatal region (behind the fricative)

Polish Sibilants

vs.

Palatography

[kasa]

Palatography

Polish Clusters• Just for kicks...

Four Fricatives

Mandarin Sibilants• Mandarin Chinese also has dental, post-alveolar and alveolo-palatal sibilant fricatives.

• The post-alveolars are sometimes retroflex

Mandarin

Before I forget…• There are two remaining fricative symbols in the IPA that we have yet to learn.

2. In Swedish, there is a fricative which combines the articulations of post-alveolar and velar [x]:

1. Some dialects of English still have a voiceless labio-velar fricative (a voiceless /w/):

Affricates

• Affricates are transcribed as stop-fricative sequences

•

• Acoustically, amplitude rises faster in affricates than in plain fricatives

• “rise time”

• Phonologically, affricates are [-continuant]

Affricate Typology• More numbers from the UPSID database:

• 522 affricates in 316 languages

• 141

• [ts] 95

• 80

• [dz] 30

• 485 affricates have sibilant fricatives

• Other affricate types are rarer:

• [pf] (German) [tx] (Navajo)

Fricative vs. Affricate

“shy”

“chime”

Polish, Again

• Polish contrasts affricates with stop + fricative sequences

Stop + Fricative vs. Affricate

Fricative Acoustics Summary• Turbulence provides the source of fricative noise

• Voiced fricatives also have a sound source at the glottis

• Obstacle turbulence tends to be louder than channel turbulence

• Sibilants are particulary high in intensity

• The filter of fricative turbulence noise changes depending on the place of articulation

• sibilants: very short filter, emphasizing high frequencies

• labials: essentially no filter (flat spectrum)

• back fricatives: longer, more vowel-like filter

• Affricates: stop-fricative sequences with shorter rise time

Review: Stops and Voicing• Stops

• Three stages: close, maintain, release

• Pressure build-up behind closure

• “Release Burst”

• Voicing

• Vocal folds are lightly brought together (adducted)

• Sub-glottal pressure higher than supra-glottal pressure

• Airflow through glottis causes cycle of vocal fold opening and closing

• Voiceless: k > t > p Voiced: b > d > g

It’s not that simple• The voicing of stops is difficult, so the contrast between

voiced and voiceless stops often takes a different form

• Making use of a different property: aspiration

• An aspirated stop has the following timing:

1. Stop closure is made

2. Airflow builds up pressure behind closure

3. Closure is released (with a “burst”)

4. Air flows unimpeded through glottis (“aspiration”)

5. Vocal folds close; voicing begins

An Aspirated Stop: [phœt]

release burst

aspiration

voicing (vowel) [t] closure [t] release burst

An Unaspirated Stop: [pœt]

release burst voicing (vowel)

A Voiced Stop: [byt]release burst

voicing (vowel)voicing (closure)

Voice Onset Time• Voice Onset Time (VOT) is defined as the length of time between the release of a stop closure and the onset of voicing.

• For aspirated stops--voicing begins after the release, so:

• VOT 50 - 150 milliseconds

• For unaspirated stops--voicing begins at the release, so:

• VOT 0 - 20 milliseconds

• For voiced stops--voicing begins before the release, so:

• VOT < 0 milliseconds

(VOT can be negative)

Thai Stops• In stressed onset position, English distinguishes between:

• unaspirated and aspirated stops.

• Languages like French, Dutch and Spanish distinguish between:

• voiced and voiceless unaspirated stops.

• Thai splits up the VOT continuum into three parts:

• voiced, voiceless unaspirated, voiceless aspirated

Thai Stops

[ba]

[pa]

English Stop Contrasts1. In onset position:

• /p/ is voiceless aspirated

• /b/ is voiceless unaspirated

2. In medial position (between voiced segments):

• /p/ is voiceless unaspirated

• /b/ is voiced

3. After /s/, in the same syllable:

• only voiceless unaspirated stops (no contrast)

Beak, Peak, Speak

Rabid vs. Rapid

English Stop Contrasts4. In syllable-final position:

• vowels preceding /p/ are short

• vowels preceding /b/ are longer

• /p/ closure tends to be longer than /b/ closure

• Moral of the story:

• Phonological voiced vs. voiceless contrast in English is abstract

• It may exhibit different phonetic manifestations

• Phonemes vs. Allophones