CDI315

Vowels

Three Ways Vowels Are Described

1. Height – How high or low the tongue is in the mouth (e.g., high, mid, low).

2. Backness – How far front or back the tongue is (e.g., front, central, back).

3. Rounding – Whether the lips are rounded or unrounded.

Source-Filter Theory

• Explains speech production as a combination of source (vocal fold vibration) and filter (vocal tract shape).

• The source provides the fundamental frequency (pitch), while the filter shapes the resonance (formants) to create different vowel sounds.

Formants

• Resonant frequencies of the vocal tract that define vowel sounds.

• F1 is inversely related to tongue height (higher tongue = lower F1).

• F2 is related to tongue backness (front vowels = higher F2; back vowels = lower F2).

Vocal Tract and Formant Frequencies

• Raising the tongue lowers F1.

• Advancing the tongue raises F2.

• Rounding the lips lowers F2.

Narrow vs. Wide Band Spectrograms

• Narrow-band spectrograms: Show more harmonic structure, better for identifying pitch and harmonics.

• Wide-band spectrograms: Show formants more clearly, better for vowel analysis.

Identifying Vowels on Spectrograms

• When given two spectrograms and a choice of two vowels, determine which is which based on F1 (which will be labeled).

• Compare F2 to differentiate between front and back vowels.

Consonants

Differences Between Consonants and Vowels

• Vowels: Produced with an open vocal tract, always voiced (except whispering).

• Consonants: Can be voiced or voiceless and involve constrictions in the vocal tract.

Consonant Types on Spectrograms

1. Stops (Plosives):

   • Silent gap followed by a burst of energy (e.g., /p, t, k/ vs. /b, d, g/).

   • Voice onset time (VOT) varies for voiced vs. voiceless stops.

2. Fricatives:

   • Continuous noise pattern (e.g., /s, z, f, v, ʃ, ʒ/).

   • Voiced fricatives have a lower-frequency voicing bar.

3. Liquids (Approximants):

   • More vowel-like but with distinct formant transitions (e.g., /l, r/).

   • /r/ has a significant F3 dip.

Differentiating Stops, Fricatives, and Liquids

• Stops: Have a closure gap and release burst.

• Fricatives: Have continuous noise energy.

• Liquids: Show smooth formant transitions similar to vowels but with distinctive formant shapes.