Single vs. double focus in English statements and yes/no questions

3.1. Graphic analysis
3. Results
Consequently, the F 0 difference between these two sentence
types becomes salient starting from the stressed syllable of the
first content word, whether or not it is focused (Fig. 3).
Figure 1: Neutral vs. single vs. double focus in English
statements. Note: S/Neutral: a statement with neutral focus;
S/Initial+Medial: a statement with double focus on the initial
and medial words. The vertical lines are syllable boundaries.
Figure 1 displays time-normalized F 0 contours of neutral-
/single-/double-focused English statements, each averaged
across 20 repetitions by 4 subjects. As can be seen, compared
to neutral focus, both single and double focus create a tri-zone
F 0 modification in English statements: pre-focus pitch range
neutralization, on-focus pitch range expansion, and post-focus
pitch range suppression (compression and lowering). While
the focused words under single or double focus seem to have
similar maximum F 0 values, the post-focus pitch range
suppression caused by single focus appears to have a greater
magnitude and a larger scope than that by focus 1 of double
focus.
Figure 4: Neutral vs. double focus in English statements vs.
yes/no questions.
Figure 4 illustrates how double focus affects the F 0 contours of
statements and yes/no questions in English, with the neutral
focus condition as reference. As can be seen from Fig. 4A,
post-focus pitch range is compressed and lowered after both
foci in double-focused statements. However, in doublefocused
questions, post-focus pitch range is compressed and
raised after focus 2, but falls gradually after focus 1.
Figure 2: Neutral vs. single vs. double focus in English yes/no
questions. Note: Q/Neutral: a question with neutral focus.
Figure 2 shows averaged time-normalized F 0 contours of
neutral-/single-/double-focused English yes/no questions. As
can be seen, post-focus pitch range is compressed and raised to
a high plateau by both single focus and focus 2 of double
focus. In contrast, the F 0 trajectory after focus 1 of double
focus falls gradually till focus 2. However, the focused words
have similar max F 0 values across single and double focus
conditions.
Figure 3: Neutral vs. single focus in English statements vs.
yes/no questions.
Figure 3 demonstrates how English statements and yes/no
questions differ under neutral vs. single focus. As can be seen
from Fig. 3C, neutral-/final-focused statements and yes/no
questions mainly differ in F 0 of the final word: falling in the
former and rising in the latter. However, when under initial
(Fig. 3A) or medial (Fig. 3B) focus, F 0 contours of these two
sentence types differ not only in the focused word (falling in
statements and rising in questions), but also in post-focus pitch
range: compressed and lowered in statements, but compressed
and raised in yes/no questions. Also, as found in [2] and will
not be discussed in detail here, there is a pitch target shift for
the stressed syllable of the content word between statements
([high] or [fall]) and yes/no questions ([rise]) in English.
Figure 5: Neutral vs. single vs. double focus in the extra-long
statements and questions.
Figure 5 displays averaged time-normalized F 0 contours of the
extra-long statements and questions under different focus
conditions. The overall patterns of the focus and sentence type
effects on F 0 trajectories are similar to those in the short
sentences discussed above, suggesting that communicative
functions are encoded similarly regardless of sentence length.
Furthermore, the difference in max F 0 between focus 1 and
focus 2 of the double-focus conditions (initial + medial,
medial + final, and initial + final) was not significantly
different across different sentence lengths in either statements
or questions (t-tests: all p > 0.05). Therefore, the following
statistical analyses were conducted based on all the sentences,
with the effect of sentence length not considered.
3.2. Statistical analysis
3.2.1. Max F 0