What contributes to the perception of musical phrases in western classical music?
Neta Spiro

Abstract:
The musical phrase
Is it? Who is it for? Where is it? What is it? When is it? Why is it?

This commonly used term, so intuitive to many musicians, has a variety
of associations with the terminology of many disciplines including
music, psychology, and linguistics. However, its nature remains
obscure.

Is it?

One of the primary aims of this study was to establish to what extent
there are common ideas about the nature of the phrase, its
description, definition, identification and function.

Who is it for?

Another aim was to identify the types of population to whom this entity is relevant. This was done through investigating: 1) verbal and musical responses provided by listeners of different musical experience, 2) musicians annotating scores as if in preparation for performance, 3) performance characteristics of publicly available recordings, 4) discussions by music psychologists, music analysts and theorists, and 5) the musical analysis of pieces according to features. This comprehensive approach is referred to as 'the combined approach' below. These response groups have been studied before, though not with such direct and detailed methods. The results indicate that common aspects of the phrase are not learnt; listeners of different degrees of musical training or lacking it altogether responded similarly to phrasing tasks and questions. 

Where is it?

This study discusses musical phrase examples of various musical genres
and media. Some of these examples were previously investigated in the
context of different disciplines. These range from folk to western
classical music. However, the core of this study is the application of
the combined approach to eight case-study pieces followed by analyses
of seven test pieces all from the western classical repertoire.
	
One of the questions concerns the extent to which the phrases and
their structures are clear 'from the score' (i.e. from the musical
features that can be identified in the score) and to what extent they
are only clear in performance. By using responses to MIDI renditions
(from listeners with different musical experience) and score
annotations (by musicians), it is observed that common phrase
structures are clear from their musical features. Musical features are
musical elements that are combined and have particular characteristics
in relation to their context. These include: cadences, relatively
large pitch intervals, long notes or rests, repetitions, and changes
in texture, motive, and harmonic rhythm.

Furthermore, the results show that there is also a rôle for
performance features (changes in tempo and intensity). The identified
tempo and intensity changes in recorded performances were also
compared with: 1) phrase structure identified by analysts, score
annotators and listeners to MIDI renditions, and 2) listeners'
responses to the same performances. These, in turn, indicate that the
same positions highlighted in performance are also identified in the
other modes, and the listeners' responses to performances relate to
the performance features. The main positions identified in response to
performances and MIDI renditions are the same, but the proportions of
responses differ. Furthermore, having heard one performance, its
phrase structure seems to be remembered and affects the phrase
identification of a subsequent performance (leaving
"footprints"). Phrasing seems to be fundamentally 'in the music' and
accentuated, clarified or obscured by performance.
 
Phrasing has mainly been discussed in the context of monophonic
music. In this study, music of different textures is explored. The
results of the combined approach indicate that in polyphonic music
(e.g. melody and accompaniment) there may be differences between the
phrase structures of different parts; phrases in different voices can
lead to and complete each other, overlap or coincide, and these
differences are often identified by participants. This indicates that
we identify both the individual phrase parts and structures of the
different musical voices, and accommodate these in a more general
identification of conflicting, complementary or similar phrase
structures.

What is it?

The term phrase has several related ones occurring in the literature
and used by participants in the current study (including, segment,
unit, chunk, sentence). Music psychological and computational
approaches to grouping, segmentation and phrasing concentrate on the
identification of boundaries, whilst other music theoretic approaches
to phrasing discuss internal characteristics.

The results of the combined approach developed in this study (and
described above), indicate that phrases include some of the following
parts: beginning, beginning of the end (implication/expectation), end
(initial arrival), prolongation (continuation of the end) and end of
the end (end of the resolution), and that each one is indicated by
specific musical features. Though all these different parts may be
present, they do not have to be for the 'phrase' to be identified,
recognised or implied. The above analyses also investigated the
relative importance of different phrase parts, which determines the
character of the phrase, such as front-heavy and end-heavy phrases,
and possible relationships between phrases, such as,
antecedent-consequent phrase pairs.

For all of these, the key seems to lie with the presence or absence of
musical features. These belong to different categories, which have
their different scopes of presence, impact and function. Some can be
instantaneous (occurring, being identified and having their
repercussion from one note to the next, such as a large pitch
interval), some can be predictive (occurring over an area and creating
expectations, including developing harmonic progressions such as
cadences), and some can be retrospective (again occurring over an area
but revealing their importance in retrospect, such as
repetitions). Different features and feature combinations seem to
systematically coincide with varying degrees of response, identified
by the combined approach. Some features and their combinations are
strongly indicative whilst others are less so. The former are rare
whilst the latter are more common. Depending on the musical context
(such as genre, instrumental combinations, or local context) common
features acquire greater importance. Moreover, this combined approach
highlights the interdependence of the musical features; different
combinations of harmonic, metrical and pitch structure, for example,
can form weaker or stronger phrase ends. The feature and phrase-part
combinations can be such that more than one possibility can arise
(sometimes resulting in 'ambiguity').

Though the relationships between the features, phrase parts and
phrases are complex and depend on several parameters, they are
formalised in a rule base. Unlike other rule bases the intention here
is to reflect the process of phrase identification, including the
'weak' phrases, by participants, and providing alternative
possibilities, using the concept of musical features developed on the
basis of the combined approach. This rule base is formalised as an
algorithm resulting in clear and consistent phrase structures, and may
in future be implemented for the study of a larger corpus of music.

When is it?

These features and feature-combinations seem to result in candidate
positions for phrase starts, ends and internal parts. Some positions
are chosen by a majority of participants whilst others are less
frequently identified. The latter coincide with weaker features and
the respective weaker phrase parts. These would probably not be
included in 'clean annotations' such as in the Essen Folk Song
Collection, but seem to be an integral and important part of the
processes of listening, performance, and analysis.

Moreover, through the combined approach discussed above and through
the use of 'click' studies, unlike in previous psychological studies,
it is here revealed that phrase parts are often identified over a
period rather than on specific notes.

Why is it?

This study indicates that the phrase is both an organising and
organised unit (in this way similar to a linguistic sentence) that is
related to memory, breath, and physical motion. It gives structure,
framework, order and reference, and interacts with other structures of
different types (such as, metrical structure). Its length is often
described as constant. However, the results of the combined approach
indicate that there is great variability in phrase length. The
identification of these units may contribute both to recollection and
comparison between similar phrases and to the more general structuring
and memory of the music. The phrase helps in following motion or
progressions from a beginning to arriving at a destination or
returning. Musical implications, and therefore expectations, seem to
play an important rôle in this progression. Moreover, from the way in
which it, its musical features and characteristics are used, and their
frequent occurrence in discussions of music analysis, performance and
perception, the phrase seems to be essential to our capacity to follow
the kind of music studied here.