PTLC2005 Juhani Toivanen ToBI or not ToBI? Testing two models in teaching English intonation to Finns 1
ToBI or not ToBI? Testing two models in teaching
English intonation to Finns
Juhani Toivanen
MediaTeam, University of Oulu and Academy of Finland
1 Introduction
ToBI is becoming a standard way of describing intonational phenomena in English
(Southern British English, General American and some Australian varieties). The twolevel ToBI approach to intonation, dating back to Pierrehumbert (1980/1987), is currently
a very influential descriptive framework of intonation in a number of languages, besides
English. ToBI has been “localized” for languages such as German, Japanese, Korean,
Greek, and there are ToBI systems under development for at least Serbo-Croatian,
Mandarin, Cantonese, and Spanish. Although ToBI systems of intonation description are
already available for a number of languages, ToBi is not an IPA system for prosodic
annotation as each separate ToBI system is specific to a language variety.
This is not the place to describe the ToBI framework in any detail but a brief outline of
the approach is in order. ToBI (Tones and Break Index) is a framework for developing
generally agreed-upon conventions for transcribing the intonation and prosodic structure
of spoken utterances in a language variety (http://www.ling.ohio-state.edu/~tobi/). In this
framework, individual syllables are tagged with such labels as H, L, (*), (%) and (-).
Intonation is described as a series of pitch accents and boundary tones, which can be
either low (L) or high (H). H is in the middle or upper part of the speaker’s pitch range,
and L is in the lowest part of the pitch range. Accents are marked off with a star (*), and
tones are annotated with a percentage sign (%) or a minus sign (-); in the system, (%)
indicates a boundary tone and (-) a phrase tone. In the coding system, H and L describe
the shape of the pitch track in relative terms (as relative “high “or “low” targets), and (*)
indicates perceived prominences and (%) indicates major phrase boundaries. The
diacritic (!) indicates downstepping in the pitch track, and HiF0 marks off the location of
the fundamental frequency peak (f0 peak) in the phrase. The annotation of prosodic
phrasing is based on a seven-category system (from 0 to 6): each word boundary
represents one of seven possibilities in the break index. A cliticized boundary is 0 and
the strongest boundary is 6, and a typical intonational phrase boundary is 4.
Although British English intonation can now be described using ToBI, the dominant
descriptive approach has been, until recently, an entirely different kind of framework.
Traditionally, British English intonation has been described with the “nuclear tone”
framework, in which the descriptive apparatus is very different from that used in ToBI.
The nuclear tone approach dates back at least a hundred years, and in an elaborate
“tonetic” (tone unit) form, the British tradition was developed by Palmer (1922). An
influential (pedagogically oriented) textbook on intonation representing the nuclear tone
and tonetic approach is O’Connor & Arnold (1973), and the tradition has been followed
by Cruttenden (1997) and Roach (1991), for example.
The tonetic or nuclear tone approach, often referred to as the Standard British model of
intonation, involves such essential concepts as nucleus, pre-head, head, tail and tone
unit or intonation unit – the ToBI system, in contrast, does not directly involve any of
these features. In the British model, the tone-unit (the basic unit of intonation) is
PTLC2005 Juhani Toivanen ToBI or not ToBI? Testing two models in teaching English intonation to Finns 2
assumed to have a fairly consistent and clearly defined internal structure: the tonic
syllable (containing the tonic or nuclear tone) is obligatory in a tone unit, while proclitic
(pre-head and head) and enclitic (tail) elements are optional. The basic assumption in
this framework is that the tonic or nucleus involves a distinct pitch movement (usually a
glide), which is the principal intonational feature in the tone unit. Such pitch movements
as fall, rise-fall, fall-rise, high-rise etc. are typical nuclear tones recognized in the British
model; the tone marks are iconic typographic symbols such as (/) for low-rise, (/) for highrise, (v) for fall-rise, etc.
The annotation principles of the ToBI system and the British nuclear tone framework are
clearly different but the same intonational structure can be described with both models.
Some examples of correspondences in the description of major pitch movements in
phrase-final position can be represented as follows: high-fall (H*L-L%), low-fall (L*L-L%),
high-rise (L*H-H%, H*H-H%), low-rise (L*!H-H%), and level tone (H*!H-L%). As can be
seen from these examples, the ToBI type of annotation appears to be more difficult than
the more iconic or isomorphic tone mark system used in the nuclear tone analysis. This
(somewhat trivial) fact may be one reason to criticize the ToBI model. On the other hand,
it can be pointed out that, with the ToBI model, good inter-transcriber reliability has been
achieved; the ToBI system is assumed to be more faithful to phonetic detail.
2 Pedagogical considerations: background of this investigation
Since the two frameworks described above appear to be rather different (at least
superficially and specifically from the viewpoint of annotation), an interesting question
seems to be which system is more suitable for teaching English intonation to second
language (L2) speakers. If one system can be shown to produce results which are
pedagogically more appropriate, teachers and lectures could make more informed
decisions when selecting the appropriate descriptive apparatus for courses in English
intonation. The issue of “superiority” in this respect can be decided, it seems, only in the
L2 language teaching context.
In the Finnish context (in Finnish universities, where “English philology” can be studied
as a major subject), the essential perspective on English intonation has been mainly
pedagogical. It should be pointed out that introductory courses in English Pronunciation
at university level do not necessarily involve any in-depth instruction in intonation: the
emphasis is on segmental phonetics and certain phonemes (e.g. fricatives), which are
known to cause problems for Finns. Weak forms/strong forms as well as rhythm – the
stress-timed aspects of rhythm in particular – are discussed in some depth, and the
basic intonation contours and their relationship with major syntactic structures are
presented. A more systematic discussion of intonation (in the form of theoretical
concepts and models) is usually reserved for advances/optional studies in English
phonetics and phonology. In the Finnish context, the ToBI model is in the curriculum
mainly in courses in general linguistics: students majoring in general linguistics and
language technology are taught basic courses in ToBI so that they can learn to annotate
spoken language corpora. The ToBI model is taught as a tool for the analysis of
language; in these theory-oriented studies, learning to actively produce intonational
phenomena in spoken language does not necessarily play a large role.
The aim of this investigation is approach the issue of which intonation framework is
“better” from a tabula rasa viewpoint. If two similar groups of Finnish university students
of English are instructed in English intonation using the same material with different
methods – one group with ToBI and the other group with the British approach – the
PTLC2005 Juhani Toivanen ToBI or not ToBI? Testing two models in teaching English intonation to Finns 3
pronunciation skills, measured in some way, should be different if the frameworks are
different enough from the pedagogical viewpoint.
3 Teaching two groups: speech data and analysis
Two groups of Finnish learners of English (first year university students of English at
University of Oulu, twelve female students in each group) took a course in British English
(RP) prosody. The test subjects were randomly assigned to the two groups. In one group,
the ToBI framework was used when describing English intonation; in the other group, the
traditional nuclear approach was used. Both groups received the same amount of oral
exercises and drills, and the same teacher (the author of this paper, a professional
phonetician) taught both groups. The students were taught the intonational structure of
English by consistently using one descriptive framework; each example, if it was
presented “on the blackboard”, was annotated using either ToBI diacritics or traditional
tone marks. The oral drills, often carried out as dialogue reading exercises in groups of
two or three persons, took place in a language laboratory. The practice material had
been selected from various sources (novels, plays, etc).
Some of the main prosody-syntax and prosody-pragmatics interface features taught in
the classroom included: “neutral”, “expected” or “polite” intonation patterns on various
syntactic structures (e.g. statement questions, echo questions, polar questions),
intonation on sentence adverbials, “open” and “closed” intonation, intonational paratones,
and the general concept of attitude/emotion expressed through intonation (e.g.
uncertainty, doubt, surprise, being impressed, etc.). The students were familiarized with
pitch tracks (f0 tracks) obtained instrumentally, and the intonation contour associated
with each track was consistently described using either the nuclear tone approach or the
ToBI framework.
After the course, the students read out a dialogue (representing a casual conversation
between friends); the speech data was digitally recorded in a sound-treated room. A
native speaker of British English (a phonetician not familiar with the subjects or the
research design) listened to the tapes in a random order and assessed the speech of
each student in terms of intonation skills. The assessment scale was 1.0-3.0 with
increments of 0.25, which is commonly used in Finnish universities. The phonetician,
who was very experienced in assessing the spoken language skills of L2 speakers, was
specifically asked to assess only the intonational aspects of the English pronunciation of
the informants; of course, it is impossible to say whether (or how much) the related
pronunciation skills (segmental aspects, rhythm, etc.) eventually affected the
assessment. The average scores were 2.32 (SD=0.15) for the Nuclear Tone group and
2.29 (SD=0.13) for the ToBI group. The difference was statistically non-significant
(independent measures t-test).
In addition to the intonation skills measures, two parameters (indirectly) related to
intonation skills were calculated: the number of rising pitch patterns in yes-no questions
and the average pitch range. For each polar question in the reading material, it was
auditorally assessed whether the pitch pattern was a rise or a non-rise (a fall or a level
tone). This was a relatively straightforward matter, and the acoustic pitch track analysis
also assisted the auditory analysis. The proportion of rising pitch patterns in the polar
questions in the Nuclear Tone group was 33 % and 31 % in the ToBI group (the
difference was non-significant, chi-square test). The average pitch range of the English
speech material produced by each informant was investigated acoustically. Pitch tracks
(f0 tracks) were obtained for each sentence produced by each speaker; each f0 value
PTLC2005 Juhani Toivanen ToBI or not ToBI? Testing two models in teaching English intonation to Finns 4
from the pitch analysis was converted to ERB using the formula given by Hermes & van
Gestel (1991). The ERB scale is assumed to be more appropriate for intonation than
either the linear (Hertz) or logarithmic semitone (ST) scales. The average pitch range in
the Nuclear Tone group was 2.3 ERB and 2.4 ERB in the ToBI group (the difference was
non-significant, independent measures t-test).
4 Discussion and conclusion
The differences between the two groups were unexpectedly small – given that most of
the students in the ToBI group consistently complained about the “difficult” compositional
nature and the complex notation system of the framework. The results are, of course,
based on a limited amount of data: the database does not involve any spoken interaction
in a real communicative situation, and the operationalization of intonation skills is not a
straightforward matter. On the other hand, the quantitative acoustic/prosodic parameters
measured reveal some additional aspects of intonation skills, and they certainly point in
the same direction as the intonation skills measures. The results do suggest that both
intonation description systems can be successfully used in teaching English prosody to
L2 speakers: good teaching results can be obtained with both systems. In the L2
teaching context, there is no reason to reject the traditional nuclear approach but, on the
other hand, also the ToBI model appears to be quite suitable from the pedagogical
viewpoint. Thus, at least in the Finnish English context, the choice between ToBI and the
Nuclear Tone approach can depend on the theoretical preferences of the teacher.
5 Acknowledgements
I wish to thank Dr. Ani Raiman for her co-operation during this research project.
6 References
Cruttenden, Alan (1997) Intonation. Cambridge: Cambridge University Press.
Hermes, Dik J. & van Gestel, Joost C. (1991) The frequency scale of speech intonation.
Journal of the Acoustical Society of America, vol. 90, pp. 97-103.
O’Connor, Joseph D. & Arnold, Gordon (1973) Intonation of colloquial English. London:
Longman.
Palmer, Harold E. (1922) English intonation with systematic exercises. Cambridge:
Heffer.
Pierrehumbert, Janet (1980/87) The phonology and phonetics of English intonation. PhD
Thesis. Massachusetts Institute of Technology. Published by Indiana University
Linguistics Club.
Roach, Peter (1991) English Phonetics and Phonology: A practical course. Cambridge:
Cambridge University Press.