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Introduction to Phonetics · December 2024

Oral Stops, Vowel Formants, and Emphatic Consonants

An exploratory acoustic comparison of American English, Egyptian Arabic, and Najdi Arabic, combining voice onset time, vowel-space measurements, and emphasis effects.

Muhammad S. AbdoInstructor: Kelly BerksonPraat + R

Full-paper summary

The project examines how languages and varieties organize stop voicing, vowel quality, and pharyngealized “emphatic” consonants. It joins three small analyses: voice onset time (VOT) in American English and two Arabic varieties; long-vowel formants in Egyptian and Najdi Arabic; and the effect of emphatic consonants on neighboring vowels.

The study is deliberately exploratory. Its value is methodological: it demonstrates a reproducible workflow from controlled recordings through Praat measurements to visualization in R, while showing how familiar phonetic diagnostics distinguish languages, dialects, and coarticulatory environments.

Participants and measurements

3
speakers: one American English, one Egyptian Arabic, and one Najdi Arabic
VOT
time between stop release and the onset of voicing
F1/F2
acoustic correlates of vowel height and frontness/backness

Recordings were segmented and measured in Praat. R was used to compare stop categories and plot vowel spaces. Emphasis was tested by comparing vowel formants adjacent to plain and emphatic consonants on both sides of the consonant.

Results in context

  • American English voiced stops had negative or near-zero VOT, whereas voiceless stops showed longer positive lag.
  • Egyptian and Najdi Arabic also distinguished voiced from voiceless stops, with visible differences between the two speakers/varieties.
  • The Egyptian speaker's long vowels were generally longer; the Najdi speaker's vowel space appeared more centralized in this sample.
  • Vowels next to emphatic consonants tended toward higher F1 and lower F2, consistent with a more open and retracted articulation.
  • The emphasis effect appeared on both preceding and following vowels, supporting bidirectional coarticulation in the measured tokens.

Visualizations and commentary

Bar chart of American English stop voice onset time
American English stop VOT
Reading the chart: voiced stops cluster around negative or short-lag values while voiceless stops extend farther into positive VOT. This is the expected aspiration/voicing contrast and provides a reference point for the Arabic comparison.
Comparison of stop voice onset time in Egyptian and Najdi Arabic
Egyptian and Najdi Arabic stop timing
Reading the chart: both Arabic speakers maintain a voicing contrast, but their trajectories are not identical. With only one speaker per variety, the difference is evidence for a hypothesis—not a population-level dialect claim.
Vowel-space comparison for Egyptian and Najdi Arabic
Long-vowel spaces
Reading the chart: F1 and F2 position each vowel acoustically. The plotted spaces suggest greater centralization for the Najdi speaker and broader duration values for the Egyptian speaker, but speaker and dialect are inseparable in this pilot design.
Vowel formants before emphatic and plain consonantsVowel formants after emphatic and plain consonants
Formants before and after emphatic consonants
Reading the charts: emphatic contexts generally raise F1 and lower F2 relative to plain contexts. That combination indicates lowering/opening and backing/retraction of adjacent vowels. Effects on both sides point to coarticulation that is not confined to one direction.

Limits and next steps

The principal limitation is the three-speaker convenience sample. Any difference may reflect an individual as much as a language or dialect. A confirmatory study should recruit multiple speakers across regions and genders, balance lexical items and phonetic environments, use carrier sentences, and model speaker and item variation statistically. The current results are best read as a technically grounded pilot that identifies measurable contrasts for that larger design.