The Role of Voice Fundamental Frequency in the Perception of Anger in Clear Speech

Purpose: While instructing talkers to speak clearly increases intelligibility, it often comes with an unintended consequence: listeners judge clear speech as sounding angry. The present signal-processing study examined whether the raised voice fundamental frequency (fo) commonly observed in clear speech causes this increase in perceived anger. Method: Sentences spoken by six talkers were edited to create four conditions: original conversational fo, conversational fo raised to match the fo of the identical sentence in clear speech, clear fo lowered to match the fo of the identical sentence in conversational speech, and original clear fo. Individual sentences were presented to 27 young adults with normal hearing, who indicated which emotion they heard out of six choices: “Anger”, “Fear”, “Disgust”, “Happiness”, “Sadness”, and “Neutral”. Results: While the expected difference in perceived anger between clear and conversational speech was found, shifting voice fo had very little effect on anger ratings. Perceived anger for the original and shifted fo conversational conditions did not differ significantly. Perceived anger was statistically significantly lower in the shifted fo clear condition versus the original clear condition, but the shifted clear speech was still rated as sounding angry over one third of the time. Conclusion: Raising the voice fo of conversational speech did not increase perceived anger ratings, while lowering the voice fo of clear speech only decreased these ratings a small amount. This suggests that other acoustic characteristics of clear speech are responsible for the unintended consequence of sounding angry.