FRANCK RAMUS
languages (4 French, 1 Rumanian, 3 Spanish, 1 German, 2
English, 1 Dutch).
Two blocks of stimuli were designed: one comprising the
40 experimental sentences to be used on the babies (sasasa
with artificial intonation), and the other the saltanaj sen-
tences with original intonation used in Exp. 2, to provide
a baseline.
Each participant heard the sentences one by one, in a ran-
dom order within each block; the order of the blocks was
counterbalanced across subjects. The task was to judge how
natural the intonation of each sentence was (from 0: very
strange to 5: perfectly natural). If artificial intonations are
equally adapted to the rhythmic structure of the two lan-
guages, they should yield similar average judgements. These
are shown in Figure 5.
intonation
Synthesis type
Figure 5. Adult subjects’ judgements of the intonation pattern of
Dutch and Japanese sentences. Error bars represent ±1 standard
error of the mean by subject.
It appears that the artificial intonations of the sasasa stim-
uli are judged to be significantly less natural in Dutch than in
Japanese sentences [F( 1,11) = 12.5, p = 0.005]. However,
the same is true of the saltanaj sentences with their original
intonation [F(1,11) = 8.4, p = 0.02]. It thus can’t be inter-
preted as an effect of mismatch between the artificial intona-
tion contours and Dutch rhythm. Rather, it seems to reflect
the influence of syllabic structure on subjects’ responses, al-
though they were instructed to report specifically about in-
tonation. From their reports, it appears that the presence of
heavy consonant clusters in Dutch (also reflected by longer
/s/s in the sasasa version) biased them in favor of Japanese.
Thus, there is a main effect of language [F( 1,11) = 21.8,
p = 0.001], and there is also a main effect of type of synthe-
sis [F(1,11) = 8.4, p = 0.02], revealing that sasasa synthesis
sounded less natural to the subjects than saltanaj. Despite
these effects that interfered with the subjects’ judgements,
it is most important to note that there is no interaction be-
tween language and type of stimuli [F (1,11) < 1], indicating
that the artificiality of the sasasa stimuli’s intonation did not
interact with the rhythmic structure of the two languages10,
which was the hypothesis under test. We therefore consider
our stimuli as appropriate to test language discrimination on
the basis of rhythm only.
Procedure
Due to the unsuccessful attempt to have the babies un-
dergo 2 shifts in Exp. 2, we abandoned the second shift and
reverted to the one-shift procedure used in Exp. 1.
Participants
Forty babies11 were successfully tested, 19 males and 21
females, with a mean age of 66 23 hours, a mean gesta-
tional age of 40; 1 1; 1 weeks and a mean birth weight of
3428 424 g. Twenty-six came from monolingual French
families, 11 from families where one or several other lan-
guages than French are spoken and 3 from families where no
French is spoken. The results of 20 additional babies were
rejected for the following reasons: rejection of the pacifier
(2), sleeping or insufficient sucking before the shift (7), cry-
ing or agitation (3), failure to meet the habituation criterion
(1), sleeping or insufficient sucking after the shift (4), loss of
the pacifier after the shift (3).
Results
Figure 6 shows the number of HA sucks per minute for the
two groups of babies. There was no significant group effect
on babies’ sucking during the 5 pre-shift minutes [F (1,39) =
1.5, p = 0.23]. However, there was a significant effect of the
habituation language [F(1,39) = 12.8, p = 0.001], babies
listening to Dutch sucking more (35.6 ± 8.3 sucks per minute
on average) than those listening to Japanese (25.8 ±9.1 sucks
per minute). To take this effect into account, we included the
habituation language factor in the usual ANCOVA. We found
that it had no significant effect on sucking patterns during the
2 post-shift minutes [F( 1,35) < 1], and most importantly,
that it did not interact with the group factor [F( 1,35) < 1].
Thus, this effect had no consequence on the overall result of
the experiment; its interpretation will be addressed in a later
section. Finally, the ANCOVA on the 2 post-shift minutes,
controlling for the 2 pre-shift minutes, showed no group ef-
fect [F(1,35) < 1], indicating that the babies didn’t discrim-
inate between the two languages.
Discussion
There are several possible interpretations of the failure of
babies to discriminate between Dutch and Japanese given
the sasasa sentences with artificial intonation. One is that
babies don’t process speech rhythm, and that language dis-
crimination experiments should be re-interpreted as reveal-
ing the processing of intonation. Another is that rhythm and
10 Note also that no floor nor ceiling effect would have prevented
this interaction to appear.
11 Eight additional babies were tested after analyses on the first
32 babies were found a little ambiguous.