Investigation of Validity of Paradigmatic Diagnosis
for Downstep in Japanese*
Kei Furukawa

Satoshi Nakamura

Division of Information Science
Nara Institute of Science and Technology
Ikoma, Japanfurukawa.kei.fi4@is.naist.jp

Division of Information Science
Nara Institute of Science and Technology
Ikoma, Japans-nakamura@is.naist.jp

Abstract—This study investigates the validity of paradigmatic
diagnosis for downstep in Japanese and seeks to ascertain
whether downstep is directly triggered by accents or not. If
the F0 peak of X is lower after an accented word (A) thanafter an unaccented word (U), X is paradigmatically diagnosed
as downstepped. However, the F0 differences between the AX
and UX sequences before X may affect the F0 difference atX. Furthermore, if a phonological boundary results in another
downtrend, it is crucial to control the phonological phrasing
in order to accurately assess the isolated effect of downstep.
We conducted a production experiment, which compared (A)(X)with both single domain (UX) and separated domains (U)(X).
Our results yield two notable findings. First, we observed amore pronounced F0 rise in the downstep conditions than in the
non-downstep conditions. Second, the paradigmatic F0 difference
between AX and UX between AX and UX decreases when X isboosted. These findings suggest that downstep is triggered byphonological boundaries, not by accents.
Index Terms—downstep, paradigmatic diagnosis, boundarydriven downstep, phonological phrase

I. I NTRODUCTION
A. Downstep in JapaneseSince the late 1960s, Japanese has been widely studied for
its intonation phonology and has been the subject of active
research on the phenomenon of downstep [1]–[12]. Words
in Tokyo Japanese are categorized as either accented (A) or
unaccented (U). Traditionally, downstep in Japanese has been
defined as a pitch range compression triggered by lexical
pitch accents [2]. Most Japanese intonation theories distinguishbetween two separate phonological categories: Minor Phrase(MiP) and Major Phrase (MaP), both of which can be merged
into a recursive phonological domain called PPhrases [8], [9],[13]. Accent culminativity and initial lowering define MiP; thedownstep domain defines MaP [8]. In these two works [8], [9],recursive PPhrases serve as the domains of initial lowering anddownstep.
There are two main methods for identifying downstep inJapanese: syntagmatic and paradigmatic [13]. In the syntagmatic diagnosis, if the pitch peak of the subsequent word
is lower than the preceding accented word, it is considereddownstep [6]. In contrast, the paradigmatic approach maintains
that if the F0 peak of word X is considerably lower after A
compared to after U, then X is diagnosed as being under theeffect of downstep [9]. The latter approach has been widelyused in various studies [2]–[5], [7]–[10], [12]. Both methods
recognize that downstep in Japanese is solely triggered byaccents.
B. Two contrasting assumptions regarding the target of downstep
Previous studies have presented two contrasting assumptions
regarding the target of downstep in Japanese. Assumption
1 states that downstep is a register shift that occurs at theboundary between the accentual H and L tone, and theaccentual L tone is the first tone which is under the effect ofdownstep [2], [3]. In other words, in AX sequences, not only
X but also the L tone within the A is the target of downstep[2], [3]. These studies consider only a single version of the L
tone present in the Japanese tone inventory: post-accentual low
tones are pronounced at a lower pitch compared to the phraseinitial L tones due to the effect of downstep on accentual low
tones [2], [3].
On the other hand, Assumption 2 proposes that the targetof downstep is only X in the AX sequence [9], [10], [12],[14]. Given the validity of this assumption, downstep is visible
only in the region shaded in gray in Fig. 1. In fact, numerous
studies have examined downstep in Japanese and consistently
reported a lower pitch height of X in AX sequences than in
UX sequences, as measured by the F0 peak of X [2]–[5], [7],[10], [12]. However, there are two possible explanations forthis difference: (1) the lower peak of X in the AX sequence
is solely due to downstep, or (2) the F0 in the AX sequence
is lowered not only by downstep but also by the realizationof accents before reaching X, and the spill-over effect ofthese accents lowers the peak of X. In other words, when
there is a large pitch difference between the AX and UX
conditions before reaching the X point, measuring the pitch at
X alone may not accurately reflect the downstep’s strength. To
accurately measure the strength of the phenomenon that occurs
within X, the proper measurement must be the differences
between the AX and UX conditions that only develop after
entering the X point, as shown in the arrows in Fig. 1.
C. Accent-driven vs. boundary-driven accounts
Existing research on downstep in Japanese consistently
identifies the H*L accent as the trigger for this phenomenon

Fig. 2. Accent-driven vs. boundary-driven accounts for downstep in Japanese.

Fig. 1. Measurement points in paradigmatic diagnosis.

[2]–[10], [12]. However, previous findings indicating a steplike downward trend in sequences of unaccented words raise
doubts about the hypothesis that accent is the trigger fordownstep. One study reports that the F0 peak for each MiP
decreases in a stair-like manner without accented words [15].
In addition, another study [11] found that parallel structures
can trigger boundary insertions, resulting in a step-like F0
downtrend resembling downstep, even in the absence of accents. The results of these two studies suggest that the insertionof phonological boundaries can result in a stair-step pitch
descent.
On the other hand, [9] posited that a phonological boundary
must follow every accent because of accent culminativity andthe anti-lapse constraint. Specifically, the AA sequence isseparated as (A)(A) due to accent culminativity, and the AU
sequence is divided into (A)(U) due to the anti-lapse constraint[9]. Since accents lead to phonological boundary insertions, itis plausible that the direct trigger of downstep is not the accent
itself but the phonological boundary insertion. In this paper,
the accent-driven account posits that downstep is directly
caused by accents, as shown by the horizontal striped arrow
in Fig. 2. In contrast, the boundary-driven account suggeststhat downstep is triggered by the insertion of phonologicalboundaries, as shown by the black arrows.
Interpretations of the paradigmatic diagnosis vary dependingon which account is considered accurate. Contrary to the AX
sequence, which must be separated, as in (A)(X), the UX
sequence can form a single domain (UX) or a separate domain(U)(X). According to the accent-driven account, downstep andboundary-driven downstep are separate phenomena. We canevaluate the downstep effect by comparing (A)(X) and (U)(X),
since both have a phonological boundary and thus exhibit
boundary-driven downstep. Additionally, (A)(X) is under theeffect of downstep. In contrast, when comparing (A)(X) and(UX), both downstep and boundary-driven downstep occur inthe (A)(X) condition, complicating differentiation between thetwo factors.
D. Research objectives
Since traditional paradigmatic diagnosis is plagued by numerous confounding factors and fails to evaluate downstep

TABLE IS AMPLE STIMULI USED IN THE EXPERIMENTa. [-accent][genitive]
item
ane-nomema’i-tokaka’rete-ita
gloss sister-GEN
dizziness-that
written-PAST’It was written as ”My sister’s dizziness.”’b. [-accent][coordinated]
item
ane-yamema’i-tokaka’rete-ita
gloss sister-anddizziness-that
written-PAST’It was written as ”sister” and ”dizziness.”’c. [+accent][genitive]
item
a’ni-nomema’i-tokaka’rete-ita
gloss brother-GEN
dizziness-that
written-PAST’It was written as ”my brother’s dizziness.”’d. [+accent][coordinated]
item
a’ni-yamema’i-tokaka’rete-ita
gloss brother-anddizziness-that
written-PAST’It was written as ”brother” and ”dizziness.”’

accurately, this study addresses this issue by modifying themeasurement position and controlling phonological phrasing,enabling a more accurate assessment of downstep.
II. E XPERIMENT
A. Experimental materials
Our experiment compared sequences of two accented words
and unaccented words preceding an accented word. The stimuli consisted of two nouns (N1 and N2) combined with aparticle. We defined Region 1 as the area where N1 and thefollowing particle are combined, and Region 2 is the area
where N2 occurs. Table I displays a set of stimuli, with theaccented vowel preceding the apostrophe.
The stimuli were constructed with two factors: Accent andParticle. The Accent factor is comprised of two levels: [accent] and [+accent]. At the [-accent] level, N1 is unaccented.
At the [+accent] level, it is accented. In the [+accent] level,a phonological boundary has to be inserted, as in (A)(A),
owing to accent culminativity and anti-lapse constraints [9].
The second factor, the Particle factor, has two levels: [genitive]
and [coordinated]. In the former, N1 is followed by a genitive
case marker -no. When N1 is unaccented, N1 and N2 can forma single PPhrase, as in (U-no A). In the [coordinated] level,
N1 and N2 form a parallel structure with a conjunction, ya.
We assumed that a parallel structure triggered the insertion

of phonological boundaries after ya [11]. Therefore, the [accent, coordinated] condition formed a separate phonologicalstructure, as in (U-ya)(A).
B. Participants
Eight native Tokyo Japanese speakers (four females andfour males, mean age 19.75 years, SD 0.83) from the Kanto
region (Tokyo, Saitama, Chiba, and Kanagawa) took part inour experiment. None ever lived outside of the Kanto area for
more than two years. None reported a history of speech or
hearing impairments.
C. Procedures and analysis
The audio recording took place in a soundproof boothat the University of Tokyo. It was captured using a Shure
WH20XLR Dynamic Headset Microphone linked to a Roland
QUAD-CAPTURE audio interface. The recording was thensaved on a computer at a sampling rate of 44.1 kHz. The
stimuli appeared individually on a screen in a pseudo-random
sequence. Participants orally recited each sentence three times,
maintaining a speech rate that was comfortable and naturalfor them. When they inserted an undesired pause or a mispronunciation while reading a sentence, they repeated it. We
recorded a total of 72 tokens: 6 items × 4 sentence types
× 3 repetitions. 120 sentences (360 tokens) served as fillers.
We annotated the sound files using Praat [14] and a script
called ProsodyPro [17]. Segmenting the conjunction from thesubsequent unstressed words relied on analyzing formants
and waveforms. Two of the three repetitions were analyzed.
We manually checked and corrected apparent errors by thealgorithm in Praat, such as octave jumps.
For each utterance, we made the following two measurement variables. The first measurement is R2MaxF0: thenormalized F0 maximum in Region 2. To factor out the F0
range variations among speakers, we converted the values of
F0 maximum x to normalized values y with reference to twopoints, using the following (1). R1 was the mean value of theF0 maximum in Regions 1 and 2 across all the data points
for the speaker, and R2 is the mean value of the F0 minimum
across all the data points for the speaker. This normalization
was previously used [10]:y=x − R2R1 − R2(1)

The second measurement variable, R2RiseSize, captures theF0 difference between the maximum F0 of Region 2 minus
the final F0 of Region 1, as indicated by arrows in Fig. 1. It
is then converted to semitones. This measurement aligns with
Assumption 1 and most likely captures the direct impact ofdownstep by removing the influence of Region 1. The accentdriven account predicts that the [+accent] level will show asmaller F0 rise than the [-accent] level since only the [+accent]level triggers downstep, which is effective solely in Region 2.
We analyzed the data through a Linear Mixed Effects (LME)model using the lmer function within the lme4 package [18]in R [19], where the subjects and items are random effects.

TABLE IIR ESULTS OF MIXED - EFFECTS MODELS FOR R2M AX F0
Condition[-accent, genitive]
vs. [+accent, genitive][-accent, coordinated]vs. [+accent, coordinated][-accent, genitive]
vs. [-accent, coordinated][+accent, genitive]
vs. [+accent, coordinated]

Predictor(Intercept)
Accent(Intercept)
Accent(Intercept)
Accent(Intercept)
Accentβ0.653-0.6780.728-0.4380.970-0.044
0.411
0.196

t
16.21
-18.5819.2-14.7321.98-1.327
9.711
6.168

p
<.001
<.001
<.001
<.001
<.001
n.s.
<.001
<.001

TABLE IIIR ESULTS OF MIXED - EFFECTS MODELS FOR R2R ISE S IZECondition[-accent, genitive]
vs. [+accent, genitive][-accent, coordinated]vs. [+accent, coordinated][-accent, genitive]
vs. [-accent, coordinated][+accent, genitive]
vs. [+accent, coordinated]

Predictor(Intercept)
Accent(Intercept)
Accent(Intercept)
Accent(Intercept)
Accent

β
1.024
0.377
2.017
1.697
1.002
0.333
2.039
1.653

t
6.092
2.836
8.212
11.877
7.685
3.198
7.409
10.174

p
<.001
<.01
<.001
<.001
<.001
<.01
<.001
<.001

We centered the factor labels of Accent and Particle to have amean of 0 and a range of 1. The backward selection [20] wasused to obtain the final models.
III. R ESULTS
The results for each variable are presented in Table II (forR2MaxF0) and Table III (for R2RiseSize). The β refers to the
fixed effects estimates. Fig. 3 displays the mean R2RiseSize
for each condition. Fig. 4 displays the normalized mean F0
for each mora, based on (1). Fig. 1 in Section I displays
the sample F0 contours for the [-accent, coordinated] and[+accent, coordinated] conditions.
For R2MaxF0, the [+accent, genitive] condition had asignificantly lower value compared to the [-accent, genitive]
condition, and the [+accent, coordinated] condition had asignificantly lower value than the [-accent, coordinated] condition. Although the mean value of R2MaxF0 for the [accent, coordinated] condition was lower than that for the [accent, genitive] condition, the difference was not statisticallysignificant. Additionally, the R2MaxF0 value for the [+accent,genitive] condition was significantly lower than that for the[+accent, coordinated] condition.
Regarding R2RiseSize, as shown in Fig. 3, the [+accent,genitive] condition had a significantly larger value than the [accent, genitive] condition. The estimated difference between
the [+accent, genitive] and [-accent, genitive] conditions was
only 0.377 semitones, which indicates a small although statistically significant difference. The R2RiseSize for the [+accent,coordinated] condition was also significantly larger than thatfor the [-accent, coordinated] condition, and the R2RiseSize
for the [-accent, coordinated] condition was significantly larger
than that for the [-accent, genitive] condition. Additionally,
the R2RiseSize for the [+accent, genitive] condition was
significantly smaller than that for the [+accent, coordinated]condition.

Fig. 3. F0 difference between maximum F0 of Region 2 minus final F0 of
Region 1 (R2RiseSize): Error bars represent 95% confidence intervals.

Fig. 4. Mean of normalized F0 means for [-accent, genitive], [+accent, genitive], [-accent, coordinated], and [+accent, coordinated] conditions represented
by solid black, solid gray, dashed black, and dashed gray lines, respectively:
Error bars indicate 95% confidence intervals.

IV. D ISCUSSION
Our results show two noteworthy findings. First, concerning
R2RiseSize, we observed a greater F0 rise for the [+accent]conditions than for the [-accent] conditions, contradicting
the prediction from the accent-driven account of downstep.
Second, regarding R2MaxF0, the paradigmatic difference inF0 height between AX and UX decreases when X is boosted.
These findings support the boundary-driven account, which
posits that accents do not directly trigger downstep.

to form (A)(A) and (U)(A). Unlike at the [genitive] level,
phonological boundaries and boundary-driven downstep are
not confounding factors at the [coordinated] level. Note thatthe [-accent, genitive] level may form (U)(A), depending on
the speech rate or other factors.
The second confounding factor is the spill-over effect ofaccents in Region 1. As shown in Fig. 1, the pitch has
already decreased considerably before entering Region 2 inthe [+accent] conditions. Even without assuming downstep,
the lowered F0 peak in Region 2 in the [+accent, genitive]
and [+accent, coordinated] conditions can be attributed to thespill-over effect of the accent in Region 1. If downstep’s scope
encompasses the accent’s L tone itself, the spill-over effectof the accent is not a confounding factor as the lowered
F0 in Region 1 is attributed to downstep. However, if weposit that downstep excludes the accentual L, the conventional
paradigmatic diagnosis comparing F0 peaks in AX or UX
cannot faithfully capture downstep’s genuine effect due tothese two potential confounding factors.
A comparison of the [-accent, genitive] and [-accent, coordinated] conditions corresponds to a comparison of (UA) vs.
(U)(A). According to the boundary-driven account, the insertion of a phonological boundary in the [-accent, coordinated]condition is predicted to cause boundary-driven downstep,
lowering the pitch in Region 2 than in the [-accent, genitive]
condition. However, our results do not strongly support thisprediction, possibly because the notation of quotation marks
led to an F0 boost by emphasizing N2, which neutralized theboundary-driven downstep. Consistent with this explanation,
an F0 boosting effect was also observed in the [-accent,coordinated] condition. In contrast, since the comparison of the[+accent, genitive] and [+accent, coordinated] conditions corresponds to a comparison of (A)(A) vs. (A)(A), the boundarydriven account does not predict any differences between them.
The difference between these two conditions is likely due tothe notation of quotation marks, which emphasized N2 andcaused a pitch boost.

A. Invalidity of traditional paradigmatic diagnosis

B. Paradigmatic difference in F0 height between AX and UX
decreases when X is boosted

Our study identified the inadequacy of using the F0 heightof N2 as an indicator for a paradigmatic diagnosis of downstep
in Japanese due to the presence of two confounding factors.
The results showed that the R2MaxF0 of the [+accent] level
was significantly lower than that of the [-accent] level inboth the [genitive] and [coordinated] levels. According to the
traditional paradigmatic diagnosis, these results suggest that
downstep occurs in Region 2 in [+accent] conditions. However, two confounding factors obfuscate whether downstep
exists independently of boundary-driven downstep. The firstis phonological phrasing, because the [+accent, genitive] and[-accent, genitive] conditions are assumed to form (A)(A) and(UA). Since there is a phonological boundary in (A)(A), thelower F0 peak in Region 2 could be due to boundary-driven
downstep, rather than downstep. In contrast, the [+accent, coordinated] and [-accent, coordinated] conditions are assumed

The F0 boosting effect of quotation marks leads to a noteworthy generalization: the paradigmatic difference in F0 height
between AX and UX decreases when X is boosted. In otherwords, the paradigmatic F0 difference between the X in AX
and X in UX becomes smaller when X is boosted by focus oradditional insertion of a boundary, compared to when X is notboosted. This observation aligns with prior research [10], [12],although this specific generalization had not been previously
established. As for our results, the estimated paradigmatic
F0 difference is 21.789 Hz in the coordinated level with theboosting effect by quotation marks, whereas it increases to35.136 Hz in the genitive level. However, the accent-driven
explanation falls short in elucidating this generalization, as it
anticipates that the sole distinction between AX and UX lies
in downstep, which would nullify the boosting effect throughparadigmatic diagnosis.

C. Evidence that the accentual L tone is not under the effectof downstep
The experimental findings of R2RiseSize contradicts theaccent-driven account under Assumption 1, which proposesthat downstep takes place at an H*L transition and that theinitial target of downstep is the accentual L in the downstep
trigger. According to the model proposed by [3], the valueof R2RiseSize in the AX sequence, R2RiseSize(AX), is expressed by (2). In contrast, the value of R2RiseSize in the UX
sequence is represented by (3). In these equations, h represents
the high-tone line, r represents the reference line, T(H) andT(L) represent relative tonal prominences between 0 and 1,
and c is a downstep constant. According to the model, (3)should be larger than (2) since c is less than 1. However, ourexperimental results contradict this prediction, showing that
R2RiseSize is larger in the downstep condition.
R2RiseSize (AX) = Hnew − Lnew
= c · (hold − r) · {T (Ha ) − [1 − T (L)]}(2)
R2RiseSize (U X) = Hold − Lold
= (hold − r) · {T (Ha ) − [1 − T (L)]}(3)
D. Evidence that downstep does not target X in the string AX
The finding that R2RiseSize is larger in the [+accent, coordinated] condition than in the [-accent, coordinated] condition
contradicts the accent-driven account even under Assumption
2: the target of downstep is X in the AX sequence. If it isassumed that downstep is a mechanism that only targets the
X in AX and lowers its pitch more in the AX sequence thanin the UX sequence, the results of R2RiseSize suggest that
downstep does not exist.
The results showed that the R2RiseSize of [+accent] level
was significantly larger than that of the [-accent] level inboth the [genitive] and [coordinated] levels. The accent-driven
account predicts that the [+accent] conditions should have amuch smaller pitch rise than the [-accent] conditions, although
this is contradicted by the results. The fact that it did notmeet the requirements of paradigmatic diagnosis, where thedownstep should have compressed the F0 peak of Region
2 at the [+accent] level, suggests a flaw in the traditional
paradigmatic diagnosis or Assumption 2.
E. Boundary-driven account: trade-off between boundarydriven downstep and edge boost
Thus far, it has been shown that the findings of this study
do not align with the accent-driven account, irrespective ofwhether Assumption 1 or Assumption 2 is employed. In thissubsection, we will explore an alternative explanation for the
results of this study using the boundary-driven account.
The boundary-driven account encompasses two key mechanisms: boundary-driven downstep and edge boost. We defineboundary-driven downstep as a phonological mechanism thatcauses a decrease in pitch for succeeding PPhrases when
there are two or more PPhrases directly governed by a
PPhrase or PClause. To illustrate, consider the expression(PPhrase1 (PPhrase2 X)(PPhrase3 Y)(PPhrase4 Z)). X, Y, and Z can beeither accented or unaccented. Since PPhrase1 directly governs
PPhrase2, PPhrase3, and PPhrase4, it satisfies the conditions
for boundary-driven downstep to occur. As a result, boundarydriven downstep in PPhrase1 causes the pitch of PPhrase2,
PPhrase3, and PPhrase4 to lower in a stair-like manner.
In addition, we define edge boost as a phonological mechanism in which the number of left edges of PPhrases is
proportional to the degree of the realization of and H tones
and the boundary tone %L. In simpler terms, when there are
multiple phonological left edges in certain situations, the F0 of
the H tone increases, and the initial lowering has a greater F0
range. Edge boost is a theoretical concept that builds uponearlier ideas, including the metrical boost [4], [5] and thecumulative rise in recursive ϕ [8], as well as the notion thatprosodic effects intensify cumulatively as multiple boundaries
coincide at higher levels [21]. Edge boost differs from metricalboost in that it can occur not only at right-branching structures
but also, unlike metrical boost, it affects not only F0 height but
also the extent of initial lowering. Studies have reported thatthe effect of F0 boost increases as the number of phonologicalleft boundaries increases both for accented sequences [5], [22]and for unaccented sequences [15].
The considerably lower values of R2MaxF0 in the [+accent,coordinated] condition, compared to the [-accent, coordinated]condition, can be attributed to two factors: the spill-over effectof accent and the trade-off between edge boost and boundarydriven downstep. Additionally, the larger R2RiseSize in the[+accent, coordinated] condition, compared to the [-accent,coordinated] condition, can also be attributed to these same
factors.
First, the spill-over effect refers to a situation where thepitch of the onset of a subsequent PPhrase is phoneticallylower due to the accent being realized as a sharp decrease in
F0 in the preceding accented PPhrase. In simpler terms, theinitial pitch in Region 2 should be similar to the final pitch
in Region 1. The term ”spill-over” suggests that the spill-overeffect of accents is independent of the phonological lowering
effect on the subsequent PPhrase.
The second factor involves a trade-off between boundarydriven downstep and edge boost. Put simply, when comparing
AX and UX sequences, the same level of edge boost in X isinsufficient to balance the effect of boundary-driven downstep
between the AX and UX sequences. On the other hand, if thedegree of pitch lowering caused by boundary-driven downstep
in X is identical for both AX and UX sequences, the F0 rise at
the beginning of X in AX becomes excessive in relation to thelevel of edge boost, assuming an equal number of boundaries
between AX and UX. Consider, hypothetically, the case where
the degree of edge boost is equal between the AX sequenceand the UX sequence, as well as the case where the degree ofboundary-driven downstep is equal between the AX sequenceand the UX sequence. Assuming that the X in both AX andAX and UX decreases when X is boosted. These findings
lend support to the boundary-driven account, suggesting that
accents do not directly trigger downstep. We propose that thelower F0 peak in the AX sequence results from the two factors:
the spill-over effect of accent and the trade-off between edge
boost and boundary-driven downstep.
Fig. 5. Schematic illustration of excessive boundary-driven downstep. The
length of the striped arrows represents the strength of the boundary-driven
downstep, while the length of the white arrows represents the strength of theedge boost.

UX sequences have the same number of left boundaries, suchas (A)(X) and (U)(X), the edge boost hypothesis predicts thesame degree of F0 rise at X. In the AX condition, the initial F0
at X is already lowered due to the spill-over effect of accents.
If the degree of edge boost realization is the same between(X) in (A)(X) and (X) in (U)(X), then the F0 peak at (X) in(A)(X) is considerably lower than the observed F0 contours
in our results. In other words, when the same degree of edge
boost is applied to X in both AX and UX sequences, it results
in an excessive lowering of the F0 peak in the AX sequence,as shown in Fig. 5. Conversely, assuming the case where thedegree of lowering F0 peak at X by boundary-driven downstep
is equal between the AX sequence and the UX sequence. In
this case, the deree of F0 rise by edge boost in AX sequece isexcessively large compared to the number of edges, because
the initial F0 at X is already lowered due to the spill-overeffect of accents in the AX condition.
To strike a balance between the requirements of edge boost
and boundary-driven downstep, considering the pitch alreadylowered due to the spill-over effect of accents, the F0 peakat X in AX should be lower than the F0 peak at X in UX.
Simultaneously, the F0 rise at the beginning of X in AX should
be greater than the F0 rise at the beginning of X in UX. If
spill-over is blocked by another factor, such as the insertionof a pause, the pitch at Region 2 should recover to a similar
extent. Alternatively, if additional boundaries are inserted tojustify the large amount of edge boost or if there are otherfactors contributing to F0 boost, the F0 peak will be similar
in both conditions. To put it differently, the boundary-driven
account predicts a decrease in the paradigmatic F0 difference
between AX and UX when X is boosted. This aligns withthe results reported in [10], [12] as well as the finding of thisstudy.
V. C ONCLUSION
Our experimental design employed a paradigmatic comparison between (A)(X) and both single-domain (UX) andseparated-domain (U)(X) conditions. Our results yield two
notable findings. First, we observed a more pronounced F0
rise in the [+accent] conditions than in the [-accent] conditions, challenging the accent-driven explanation of downstep;
the F0 rise experiences greater compression under downstep
conditions compared to non-downstep conditions. Second, theparadigmatic F0 difference between AX and UX between

ACKNOWLEDGMENT
Part of this work was supported by JST SPRING Grant
Number JPMJSP2140 and JSPS KAKENHI Grant Number
JP21H05054.
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