1. Modeling credibility
Acoustic perceptual correlates of
news reading by native and non-
native speakers
A. De Meo, E. Pellegrino, M. Pettorino, M. Vitale
University of Naples L’Orientale

2. Credibility assessment
• Message credibility is generally agreed to
result from an interaction of
– message characteristics (related to message
content, encompassing factors such as
plausibility, internal consistency, and quality)
– receiver characteristics (e.g., cultural
background, previous beliefs)
– source characteristics
(e.g., expertise, trustworthiness, regiornal or
foreign accent)

3. speaker’s accent
• Foreign accent, i.e. the acoustic features of an
utterance (segmental and/or suprasegmental)
perceptually different from the average
production of a native speaker, may impact
speaker’s credibility because it activates
prejudices and stereotypes

4. research questions
• What happens to credibility, when stereotypes
about non-native speakers are neutralized by
presenting the message as created by a native
speaker and simply delivered by a non-native
speaker?
• Does foreign accent make the speech harder to be
processed?
• Does this processing difficulty make the foreign
accented speech harder to be believed as
hypothesized by the theory of “processing fluency”?

5. processing fluency
• According to the socio-psychological concept of
“processing fluency”, the way stimuli are judged
depends on the cognitive load involved in the input
processing.
(Oppenheimer 2008; Schwarz 2004, Reber & Schwarz, 1999 )

6. 5 PERCEPTUAL TESTS (1275 listeners)
• Test 1: 4 voices (2 NS and 2 Chinese NNS C1 level, mild & strong
FA); 301 Italian listeners
• Test 2: 5 female voices (1 NS and 4 NNS with a strong foreign
accent, A2-B1 levels); 265 Italian listeners
• Test 3: test 1 voices, with tonal range and silent pauses
artificially increased and decreased through WinPitch; 120
Italian listeners
• Test 4: test 2 voices, with errors and disfluencies
removal, segmental duration and tonal range cloned from the
native voice using Praat (transplantation); 270 Italian listeners
• Test 5: 1 female native voice, L1 Italian; 319 Italian listeners
research design

7. research design
• test 1 and 2: NATURAL SPEECH - L2 Italian
– Focus on degree of foreign accent:
2 NNS with same L1, Chinese, male and female, same
age, both advanced learners of L2 Italian (C1), differing
only for the degree of foreign accent (F = strong, M =
mild).
– Focus on different L1s and on different L2 levels of
competence:
4 NNS with a strong foreign accent, all female
voices, same age, diverging for level of competence (two
A2 and two B1), and L1s (A2: Arabic and Japanese, B1:
Chinese and Vietnamese).

8. research design
• test 3 and 4: SYNTHESIZED SPEECH - L2 Italian
– Focus on prosody:
manipulation of tonal range and silent pauses
(2 Chinese NNS and 2 Italian NS)
– Focus on segmental and suprasegmental anomalies:
• segmental errors and disfluencies removal
• segmental duration cloning from the native voice
• tonal range cloning from the native voice
(4 NNSs and 1 NS)

9. research design
• test 5: NATURAL and SYNTHESIZED SPEECH - L1 Italian
– Focus on L1 anomalies and disfluencies:
• transplanted disfluent speech
• elicited disfluent speech
(1 NS of Italian)

10. • bizarre-but-true news from around the world
read in Italian
• organized in form of radio news
magazines, pretending to make a survey on
media reliability, in order to avoid to focus the
attention on foreign voices
corpus

11. • degree of perceived accent (native
accent, mild foreign accent, strong foreign
accent)
• comprehensibility, i.e. listener’s estimation of
difficulty in understanding an utterance
(poor, sufficient, good)
• credibility of each news item (true, false)
perceptual assessment

12. RESULTS
test 1-4
L2 Italian

13. 0
20
40
60
80
100
original disfluencies &
pauses
manipulation
errors removal duration & pitch
cloning
"poor comprehensibility" "strong foreign accent" false
the worst non-native voice of the corpus
Arabic L1, A2 of L2 Italian - CEFR
• high percentage of disfluencies (35%)
• low degree of comprehensibility (92% “poor”)

14. 0
20
40
60
80
100
IT_M IT_F CH_M CH_F
"poor comprehensibility" "strong foreign accent" false
NS and NNS (C1 of L2 Italian - CEFR)
• no disfluencies
• high degree of comprehensibility (96-98% “good”)

15. TEST 1-4 (L2 Italian)
• variation in credibility is not exclusively dependent on the
message content;
• credibility is rather delivered by the comprehensibility level
of the utterance;
• comprehensibility, in turn, is primarily affected by the
features often characterizing the L2 speech: the more the
disfluencies, wrong pauses, interruptions and anomalous
tonal variations, the lower the comprehensibility.
results

16. • The reason of the mistrust of the listener to the message
should therefore not be sought in the opposition
“foreign/native”, but rather in the degree of
comprehensibility of the utterance and, therefore, in the
level of difficulty encountered in its decoding.
results

17. What happens if the native speaker is as
disfluent as the non-native speaker?
test 5 - L1 Italian

18. • 1 Italian NS (female)
• corpus
– 4 bizarre-but-true news
– natural speech
• elicited disfluencies (reading distance: greater than the
optimal)
• plain reading
– synthesized speech
• transplantation of non-native anomalies and
disfluencies (Arabic speaker, A2 CEFR, highly disfluent)
on the Italian plain reading
materials and methods

19. – Anomalies (segmental
duration, pitch contour)
– Disfluencies
(repetitions, vocalizations,
nasalizations, interruption
s, etc.)
transplanting NNS features

20. spoken time composition
17
24
59
elicited disfluent speech
% silences % disfluencies % phonation
13
25
62
transplanted disfluent speech
% silences % disfluencies % phonation
• comparable speech time composition
• segmental and prosodic differences

21. • 50 native Italian listeners
– 2 groups
• 8 news
– 4 transplanted disfluencies
– 4 elicited disfluencies
– 2 random orders (2 transp. + 2 elicit.)
• degree of foreign accent (FA)
– native accent, mild foreign accent, strong foreign
accent
pretest

22. pretest
55
1
41
44
94
0
20
40
60
80
100
elicited transplanted
foreign accent degree (average values - %)
native accent mild foreign accent strong foreign accent
0
47 53
0
20
40
60
80
100
Chinese C1

23. • 319 listeners
– 4 homogeneous groups, aged 21-24, M/F, university
students
• 8 items - 4 different orders
– 4 news - plain reading (PR)
– 4 news - elicited disfluencies (ED)
• assessment
– foreign accent (native accent, mild FA, strong FA)
– comprehensibility (poor, sufficient, good)
– credibility (true, false)
perceptive test

24. perceived accent
global values - %
96
52
4
43
0
5
0
10
20
30
40
50
60
70
80
90
100
plain reading disfluent reading
native accent mild foreign accent strong foreign accent

25. comprehensibility
global values - %
92
12
7
71
1
16
0
10
20
30
40
50
60
70
80
90
100
plain reading disfluent reading
good sufficient poor

26. credibility
global values - %
64
3736
63
0
10
20
30
40
50
60
70
80
90
100
plain reading disfluent reading
TRUE FALSE

27. 0
20
40
60
80
100
native accent good comprehensibility TRUE
0
20
40
60
80
100
first second
plain reading (NS)
0
20
40
60
80
100
first second
disfluent reading (NS)

28. in conclusion
• Current findings indicate that there is a direct
relationship between comprehensibility and
credibility, supporting the “processing fluency” theory
• Low comprehensibility affects credibility of both native
and non-native disfluent speech
• A NNS having a strong foreign accent but an advanced
level of L2 competence has the same chance of
communication success of a NS, in terms of credibility
• There is only an indirect relationship between foreign
accent and credibility, mediated by comprehensibility

29. References
De Meo, A. (2012), “How credible is a non-native speaker? Prosody and
surroundings”, in Methodological Perspectives on Second Language Prosody.
Papers from ML2P 2012, Padova: CLEUP, pp. 3-9.
http://www.maldura.unipd.it/LCL/ML2P/proceedings.html
De Meo, A., Pettorino, M., Vitale, M. (2012), “Non ti credo: i correlati acustici della
credibilità in italiano L2”, in G.Bernini, C. Lavinio, A. Valentini, M. Voghera (a cura
di) Atti dell’XI Congresso dell’Associazione Italiana di Linguistica
Applicata, “Competenze e formazione linguistiche. In memoria di Monica Berretta”.
Guerra Edizioni, Perugia, pp. 229-248.
De Meo, A., Vitale M., Pettorino, M., Martin, P., (2011), “Acoustic-perceptual credibility
correlates of news reading by native and chinese speakers of Italian”, in Wai-Sum
Lee e Eric Zee (eds.), Proceedings of the 17th International Congress of Phonetic
Sciences, City University of Hong Kong, Hong kong, Cina, pp: 1366-1369.
Gluszek, A., Dovidio, J.F. (2010), “The way they speak: Stigma of non-native accent in
communication”. Personality and Social Psychology Review 14, pp. 214-237.

30. Lev-Ari, S., Keysar, B. (2010), “Why don’t we believe non-native speakers? The
influence of accent on credibility. Journal of Experimental Social Psychology
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Pettorino, M., De Meo, A., Pellegrino, E., Salvati, L., Vitale, M.
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Speech Sciences (AISV 2011), Roma: Bulzoni editore, CD (9 pp.).
Pettorino, M., De Meo, A., Vitale, M. (2012), “Transplanting credibility into a
foreign voice. An experiment on synthesized L2 Italian", in H. Mello, M.
Pettorino, T. Raso (eds.), Speech and Corpora, Proceedings of the 7th GSCP
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31. Thank you!