Echo delay thresholds produce distinct perceptual and speaking effects

Evidence

A wellknown effect is the raising of one’s voice in the presence of loud background noise, called the Lombard effect (Lane and Tranel, 1971). In contrast, we lower the volume of our voice when we are played back our voice loudly. Delaying the echo increases the perception of discomfort. For small delays (<10 ms) and high levels, the echo interferes with the sound coming directly from the mouth of the speaker, leading to the perception of colouration due to comb filtering. Medium delays (10–30 ms) lead to the perception of hollowness in one’s voice, and for larger delays (> 30 ms) we perceive a clear, distinct echo. When the delay is large (> 200 ms) and the level of the echo is high, subjects experience difficulty in producing words (Appel and Beerends, 2002). The difficulties may be simply because, when producing a syllable, one’s own voice present in the ear canals due to the echo has the timbre of the previous syllable, which causes confusion in our neural speech production system. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 2459

Categorization

• QUESTION: The neural-speech-production confusion mechanism for large-delay echoes is presented tentatively — worth chasing the Appel and Beerends source for the experimental evidence.
• XREF: Connects to auditory feedback control of speech production, which runs parallel to the book’s earlier discussion (in Soundscape material) of how ambient sound shapes production.