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The vast majority of African linguists still rely on their naked ears to determine pitch registers and tone rules. In recent years, timid efforts have been made by some to complement their impressionistic analyses with acoustic phonetic measurements. Yet, they still interpret the acoustic data impressionistically. In this paper, I propose a new approach based on the Critical Band Theory (CBT). This theory was pioneered by Physicist Harvey Fletcher who postulated on the basis of mathematical calculations that the basilar membrane compartmentalizes speech signals into frequency bands. He demonstrated this in various experiments that culminated in his seminal paper, Auditory Patterns (1940). Seven years later, von Békésy, another physicist, published The Variations of Phase along the Basilar Membrane with Sinusoidal Vibrations in which he proved clinically that Fletcher’s theory was grounded in physiological reality. There are three main advantages in using CBT to study pitch registers and tone rules in African languages. First, it correlates F0 measurements directly with a pre-existing critical band template. Therefore, pitch registers are determined independently of the researcher’s preconceived ideas about pitch levels. Secondly, the findings are authoritative because the critical band system has been endorsed by the American National Standards Institute (ANSI), the International Standardization Organization (ISO), and the International Electrotechnical Commission (IEC) for designing and manufacturing audio products and sound level meters. Last but not least, CBT-based findings are falsifiable and applicable to all tone languages.

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

Author Bio

Ettien Koffi, Ph.D. in linguistics from Indiana University, teaches linguistics at Saint Cloud State University, MN. Author of many peer-reviewed articles on various topics in linguistics and of four books: Language Society in Biblical Times (1996), Paradigm Shift in Language Planning and Policy: Game Theoretic Solutions (2012), Applied English Syntax (2010, 2015), and the New Testament in Anyi Morofu (2017), a task which took over 25 years. Specializing in acoustic phonetics, dialect variation, and emergent orthographies, his current research centers on speech acoustics of L2 English (within the Speech Intelligibility Framework), Central Minnesota English, and Anyi. He can be reached at



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