Teaching and Learning Guide for: Speaking and Hearing Clearly: Talker and Listener Factors in Speaking Style Changes
Authors: Smiljanic Rajka , Bradlow Ann 
Published: March 2010

This guide accompanies the following article: Rajka Smiljanic and Ann Bradlow, ‘Speaking and Hearing Clearly: Talker and Listener Factors in Speaking Style Changes’, Langauge and Linguistics Compass 3/1 (2009): DOI: 10.1111/j.1749‐818X.2008.00112.x

Author’s Introduction

Clear speech is a listener‐oriented speech modification that talkers naturally and spontaneously adopt when listeners have perceptual difficulties due to a hearing impairment, different native language, or presence of noise in the environment. Clear speech research is motivated by the need to understand how these talker‐, listener‐, and signal‐related factors impact normal speech intelligibility. Over time, clear speech studies have explored speech intelligibility variation for a wide range of talker and listener groups, such as normal hearing, hearing impaired, native, non‐native, younger and elderly adults, and individuals with Parkinson disease. This body of research has also examined various speech signal conditions, such as signals presented in noise and reverberation and signals modified through digital speech enhancement procedures. The over‐arching aim of these studies is to provide insight into, on the one hand, which conversational‐to‐clear speech acoustic–articulatory modifications contribute to increased intelligibility and, on the other, how the nature of the listener’s perceptual deficit determines which of the clear speech strategies will be most beneficial. Through these investigations, clear speech research provides a window into the interaction of lower level, sensory and perceptual and higher level, cognitive factors that affect language processing. Furthermore, clear speech research informs us about the speech production mechanisms of plasticity that allow talkers to adjust their output to the communicative situation, and about the speech perception processing mechanisms that allow listeners to take advantage of these acoustic–articulatory modifications. This research, thus, has important theoretical implications for developing reliable models of linguistic behavior as well as practical implications for various populations (e.g., non‐native and clinical) where speech production and intelligibility are compromised.

Key Readings (in the order they are discussed in the Review)

Picheny, M. A., N. I. Durlach, and L. D. Braida. 1985. Speaking clearly for the hard of hearing I: Intelligbility differences between clear and conversational speech. Journal of Speech and Hearing Research 28: 96–103.

Picheny, M. A., N. I. Durlach, and L. D. Braida. 1986. Speaking clearly for the hard of hearing II: Acoustic characteristics of clear and conversational speech. Journal of Speech and Hearing Research 29: 434–46.

Ferguson, S. H., & Kewley‐Port, D. 2007. Talker differences in clear and conversational speech: Acoustic characteristics of vowels. Journal of Speech, Language, and Hearing Research 50: 1241–1255.

Krause, J. C. and L. D. Braida. 2004. Acoustic properties of naturally produced clear speech at normal speaking rates. Journal of the Acoustical Society of America 115(1): 362–78.

Liu, S. and F.‐G. Zeng. 2006. Temporal properties in clear speech perception. Journal of the Acoustical Society of America 120(1): 424–32.

Smiljanić, R., and A. R. Bradlow. 2005. Production and perception of clear speech in Croatian and English. Journal of the Acoustical Society of America 118(3): Pt. 1, 1677–88.

Bradlow, A. R., and T. Bent. 2002. The clear speech effect for non‐native listeners Journal of the Acoustical Society of America 112: 272–84.

Smiljanic, R. and A. Bradlow. 2008. Temporal Organization of English Clear and Plain Speech. Journal of the Acoustical Society of America 124.5: 3171–82.

Zeng, F.‐G., and S. Liu. 2006. Speech perception in individuals with auditory neuropathy. Journal of Speech, Language, and Hearing Research 49: 367–80.

Focus Questions

What other speaking style changes are similar to clear speech modifications and in what way? In what aspects may these other speaking style changes differ from clear speech? Explain why some of the different effects may arise?

How does the H&H Theory (Lindblom, 1990) provide a conceptual framework for understanding the origin and nature of conversational‐to‐clear speech adjustments?

What are the broad and long‐term goals of clear speech research in terms of its production and perception?

Why is term ‘conversational’ speech not completely accurate in describing the elicited speech in most clear speech studies? How would you adapt the talkers’ task to elicit more spontaneous conversational and clear speech? What problems would this pose for your measurements and analyses?

Why is it difficult to establish a direct link between individual acoustic–phonetic cues and their impact on intelligibility? What possible role in language processing could some of these conversational‐to‐clear speech modifications play (e.g., speaking rate decrease, vowel space expansion, increased energy in the 1000–3000 Hz range of long‐term spectra)?

How do cue enhancement studies address the link between individual acoustic‐phonetic cues and intelligibility? What new challenges are introduced with using these signal‐processing techniques?

How does examining clear speech production and perception for different talker and listener groups (e.g., native vs. non‐native, younger vs. elderly adults, normal hearing vs. hearing impaired) contribute to our understanding of variability in intelligibility?

Provide a detailed description of the sound structure of a language that has not been previously studied in clear speech research. Make predictions about the hyperarticulation strategies that speakers of that language may use in enhancing intelligibility and which may reflect language‐specific sound properties.

How does exploring clear speech of single words vs. longer and more complex speech contribute to our understanding of production and perception processes?

What impact can insights from clear speech research studies have on work with clinical populations? How do results from clinical studies inform questions central to clear speech research? How can clinical studies aid in examining plasticity in clear speech production?

How to Use The Article/Topic?

This review article (and the cited papers within relevant sections) can be used to develop a clear speech seminar or to enhance discussions in other classes revolving around, for instance, speech intelligibility, speech variation, and signal processing, in Linguistics, Communication Sciences and Disorders and Engineering departments. The topics covered may include:

Clear speech production: this topic will consider the acoustic–articulatory modifications that typically characterize clear speech. You may also consider how these modifications relate to other speaking style changes (e.g., child‐directed speech and Lombard speech). Consider how different elicitation methods, i.e., instructions given to the talkers or presence of a dialog partner, may affect the clear speech production strategies. Make predictions about how different languages may vary in implementing clear speech modifications reflecting the language‐specific sound structure.

Clear speech perception: the focus of this topic is on listener characteristics that affect clear speech intelligibility. Consider how the nature of different perceptual problems affects the level of clear speech intelligibility advantage and which clear speech acoustic–phonetic cues are beneficial for various listener populations. Propose ways of studying the clear speech effect on other levels of speech processing (e.g., speech stream segmentation and lexical access). Consider how you would go about exploring a direct link between acoustic–phonetic features of clear speech and their impact on intelligibility.

Clear speech and cue enhancement procedures/speech technology: the students should familiarize themselves with techniques available to use in cue enhancement procedures. Consider what are the benefits and potential problems in applying signal‐processing methods in clear speech research. What acoustic cues could be examined this way? Consider how these speech processing systems could improve speech perception for various listener populations.

Clear speech in the clinic: this topic explores what can be learned about the nature of a production or perception difficulty from clear speech studies with various clinical populations. Consider whether and how clear speech production and perception tasks can be used to diagnose various deficits. Think about whether and how clear speech training can be used to improve production and perception in various clinical populations.