Vowel Formants in Normal and Loud Speech.

Area of Science:

• Phonetics
• Speech Acoustics
• Linguistics

Background:

• The relationship between speech loudness and vowel articulation is debated.
• Claims suggest increased loudness leads to exaggerated vowel production, expanding the acoustic space.

Purpose of the Study:

• To investigate how vowel formant frequencies (F1, F2) change between normal and loud speech.
• To assess if loudness naturally leads to exaggerated vowel articulation across different speaking tasks.

Main Methods:

• Eleven German-speaking women produced normal and loud speech in reading, question-answering, and recall tasks.
• Loudness was elicited naturally by varying interlocutor distance.
• Formant frequencies (F1, F2), sound pressure level, and vowel space area were analyzed for stressed vowels.

Main Results:

• High, tense vowels exhibited limited formant variation with loudness.
• Vowel space area was reduced in a spontaneous recall task compared to reading or question-answering.
• Formant frequency changes (F1, F2) due to loudness were inconsistent and often not significant, with speaker variability observed.

Conclusions:

• Naturalistic loud speech in typical speakers does not consistently alter vowel formant frequencies.
• The assumption that increased loudness automatically expands vowel space is questioned by these findings.