Stop Place Contrasts before Liquids

Edward Flemming

MIT

Does phonology have a biological grounding?

• Phonology is shaped by the nature of speech perception and speech production.

• Speech production and speech perception depend on biological endowments.

• A case study adopting this approach to the analysis of a phonological pattern: Restrictions on stop place contrasts before laterals.

Restrictions on coronal-lateral clusters

• Many languages allow initial [pl, kl]/[bl, gl] clusters, but exclude [tl, dl] (Kawasaki 1982).• E.g. English, German, Norwegian, Thai,

etc• English:

[b-g, p-k] contrast before [l], blue-glue, plan-clan initial [dl-, tl-] are not possible.

Restrictions on coronal-lateral clusters• This is a result of a dispreference for coronal-dorsal stop

contrasts before laterals (Flemming 1995).

• Some languages reverse the English pattern, [tl-, dl-] OK, but no *[kl-, gl-].

• e.g. Haroi and other Chamic languages (Mudhenk & Goschnick

1977), Katu dialects (Wallace 1969):

• Some languages have free variation between coronal and velar stops before lateral (but contrast elsewhere), e.g. Bolton English (Shorrocks 1998), Mong Njua (Lyman 1974)

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Restrictions on coronal-dorsal contrasts before [l]

• Kawasaki (1982) hypothesizes that this dispreference is due to perceptual similarity of [dl-gl], [tl-kl].

• General hypothesis: There is a preference for perceptually distinct contrasts.Before [l], contrasts between coronal & dorsal stops are

not very distinct.

Previous evidence:

• Kawasaki (1982): Evidence from 1 speaker that formant transitions are very similar in [dl-, gl-].

- But bursts can be sufficient to distinguish stops.

Restrictions on coronal-dorsal contrasts before [l]

• Further investigate Kawasaki’s hypothesis through acoustic analysis of American English (and Hebrew).

• Hypothesis: English [dl-gl] and [tl-kl] contrasts would be less distinct than legal stop place contrasts (e.g. [bl-gl], before vowels).

• How do we infer the expected realization of [dl-, tl-]?• Other stop-liquid clusters• Medial [-dl-, -tl-] clusters• [tl-, dl-] in languages that allow these clusters (e.g.

Hebrew, Russian).• But NB languages that allow these contrasts may realize stop-

liquid clusters in a different fashion, e.g. less gestural overlap.

• Focus on voiced clusters (Am. English medial -tl- often realized as -ʔl-).

Materials

• 6 near-minimal pairs for bl-gl, e.g. blow, glow

• 9 triplets for [b, d, g], each preceding the same set of nine vowels.

• Sentence frame ‘Say X to me’• Presented twice in random order• 5 native speakers of American English, 4 female, 1 male.

• 6 near-minimal pairs for medial -dl-gl-, e.g. Ridley, wrigley

• Same frame, presented twice in random order• 3 native speakers of American English, all female

Cues to stop place contrasts

• Prevocalic stops (e.g. Dorman et al 1977):

Release burst - transient + fricationFormant transitions

• Examine similar cues in stops preceding [l].

burstformant transitions

Time (s)26.1405 26.5479

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Measurements

Formants:• Measured F2 and F3 as soon as possible after the end of

the burst.

Burst:• Burst duration - from stop release to onset of first formant.• Shape of spectrum of first 6 ms of the burst.

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Quantifying burst shape

• Measured from smoothed spectra (Hanson & Stevens 2003) Calculate a series of seven DFTs on 3 ms windows at 1 ms

intervals. Average these spectra.

Quantifying burst shape

bl bursts

gl bursts

• Burst peak: frequency of the highest amplitude in the spectrum

• Amid-Ahi (cf. Suchato et al 2005)

•Amid = average amplitude from 1.25 kHz - 3 kHz

•Ahi = average amplitude from 3.5 kHz - 8 kHz

mid high

Stop-[l] clusters - formants

• English stops are not well differentiated by formant transitions before [l].

Formant onsets

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F2 F3

Hzdlgl

Formant onsets

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F2 F3

Hzblgl

• Initial [bl-, gl-]• No significant differences

in formant onsets.

• Medial [-dl-, -gl-]• Small differences in F2 onsets

• -dl- seems to allow more coarticulatory influence of a preceding front vowel.

Stop-[l] clusters - formants

• Stops are not well differentiated by formant transitions before [l].

• Similar results from a preliminary study of Hebrew initial [bl-, dl-, gl-], [pl-, tl-, kl-] clusters (3 speakers):

• Stops appear to be overlapped with following lateral, so formants at onset are largely determined by [l].• Effect is particularly striking for English [-dl-], since prevocalic

[d] is usually characterized by relatively high F2 at release (~2100 Hz)

• Possibly lateral release of [d] facilitates the low F2 onset (1311 Hz)

Stop-l clusters - burst

• [gl] is more compact than [bl].

• [gl] has a longer burst than [bl].

* p < 0.01

frequency of peak

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bl gl

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burst duration

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bl gl

burst duration (ms)

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• [gl] burst has a higher peak than [bl] burst.

Amid-Ahi

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• Initial [bl-, gl-] clusters are distinguished by burst quality and duration.

Stop-l clusters - burst

• Medial [-dl-, -gl-] are also differentiated by their bursts.• But the properties of [-dl-] bursts deviate substantially

from prevocalic [d] bursts in the direction of [g]/[gl] bursts.

burst duration

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dl gl

burst duration (ms)

Amid-Ahi

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dl gl

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frequency of peak

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dl gl

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Lateral release

• The properties of the [dl] burst are expected consequences of laterally releasing [d].

• Centrally released [d] burst has significant high frequency energy because it is filtered by the short cavity in front of the alveolar closure.

• But with lateral release, the front cavity includes the side passages opened up by lowering the sides of the tongue, and thus is significantly longer.

• Hence lower frequency peak, more compact burst shape.

Dispreference for [d-g] contrast before [l]

• Stop-[l] clusters are distinguished by burst not formant transitions.

• The [bl-gl] contrast is plausibly more distinct than [dl-gl] because the burst of laterally released [d] is compact like a velar burst.

• Not clear what leads to a preference for the labial-coronal contrast in Chamic etc.• preference for homorganic clusters?

bl- -dl- -gl-

Lateral release

• Similarity between [dl] and [gl] appears to be a result of lateral release of [d].

• Lateral release may play a role in unusually low F2 onset in [dl].

• Lateral release results in non-canonical [d] burst.

• So if [d] were not laterally released, [dl]-[gl] contrast should be more distinct.

• Thanks to Patrick Jackson Jones

Stop-l clusters

Time (s)0.276954 0.524867

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Time (s)0.278185 0.499791

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(ba)dly (Ba)gley

br vs. dr vs. gr - Formants

• Formant transitions distinguish [br, dr, gr].

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Formant onsets

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brdrgr

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br vs. dr vs. gr - burst

• burst distinguishes [br, dr, gr]

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burst duration

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br dr gr

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frequency of peak

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Amid-Ahi

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