Table 1 Summary of included studies.

Arciuli and Bailey (2019)⁴²

20, 18, 7.38 ± 1.55

20, 18, 7.21 ± 1.78

Picture-naming strategy

Pairwise variability index (PVI)

Stress contrastivity: ASD < TD

Arciuli et al. (2020)⁴³

16, 13, 5.73

16, 3, 4.65

Picture-naming targets

Duration, F0, intensity of the first two vowels for PVI

Results of acoustic analyses indicated no statistically significant group differences in PVIs

Bone et al. (2016)⁴⁴

95, 75, 8.8 ± 2.6

81, 56, 8.3 ± 2.5

Narration

Pitch dynamics, rate of speech, prosodic attributes, and turn-taking

Prosodic variability increases 

in interactions with higher severity ASD

Pitch variability: ASD > TD

Bonneh et al. (2010)⁴⁵

41, 32, 5 ± 1.1

42, 17, 5.1 ± 0.7

Picture-naming task

Long-term average spectrum and pitch variability

ASD spectrum was shallower and showed

less harmonic structure. pitch range: ASD > TD

Brisson et al. (2014)⁴⁶

12, 10, 0.365 ± 0.073

11, 9, 0.309 ± 0.115

Extracted infants’ and mothers’ voice productions recorded through the family home movies

Mean duration and pitch

ASD infants’ productions were not different in duration and pitch, however less complex modulated productions were created by ASDs

Chan and To (2016)⁴⁷

19, 19, 25.72 ± 3.63

19, 19, 25.50 ± 3.21

Recording of narrative production

F0, pitch variability and the total number and the type of sentence-final particles from

narrative samples

Pitch range: ASD > TD

F0: ASD > TD

Pitch variability: ASD > TD

Choi and Lee (2019)⁴⁸

17, NR, 8.23 ± 1.55

34, NR, 8.27 ± 1.725

Conversation samples

Voice intensity variation, prosody, pitch

Intensity, pitch, and intonation change: ASD > TD

DePape et al. (2012)⁴⁹

12, 12, 23.2 ± 6.6

6, 6, 26.3 ± 4.0

Verbal responses

Overall range-fall (the difference between the peak and the proceeding lowest pitch value),

High language functioning ASD(HASD) had higher while moderate language functioning had lower pitch range compared with TD, higher range-fall for HASD

Demouy et al. (2011)⁵⁰

12, 10, 9.75 ± 3.5

12, NR, NR

Language assessment tasks

Sentence duration

Sentence duration for all types of Descending, falling, rising and floating sentences: ASD > TD

Diehl and Paul (2013)¹³

24, 16, 12.31 ± 2.32

22, 15, 12.21 ± 2.64

An instrument designed to assess prosody performance in children

Acoustic measures of prosody

Utterance duration, pitch range, pitch variance and mean pitch: ASD > TD

Diehl et al. (2009)¹⁵

21, 19, 13.58 ± 2.10

21, 19, 13.24 ± 2.09

A cartoon for eliciting narratives and Gestures

Standard deviation in F0, average fundamental frequency across the entire narrative

F0: ASD > TD

Pitch variability: ASD > TD

Drimalla et al. (2020)²²

37, 19, 36.89

43, 21, 33.14

Conversation between the participant and an actress

Prosodic features for each frame: f0, jitter (pitch perturbations), and shimmer (amplitude perturbations) and the root-mean-square energy

F0: ASD > TD

Esposito and Venuti, (2009)⁵¹

10, 5, 1.4 ± 0.125

10, 5, 1 ± 0.07

Cry Observation codes

Duration

Longer screaming duration for ASD

Filipe et al. (2014)¹⁰

12, 10, 8.58 ± 0.51

17, 10, 8.35 ± 0.49

PEPS-C test for assessing the receptive and expressive prosodic skills of children

Duration, pitch (range, mean, maximum, and minimum), and intensity (mean, maximum, and minimum)

Voice duration , pitch range, mean pitch, maximum pitch: ASD > TD

Fosnot and Jun (1999)⁵²

4, 4, 4–17

4, 4, 4–17

Declarative and question sentences

Mean duration and p range

Longer voice duration in ASD group

Grossman et al. (2010)³⁶

16, NR, 12.33 ± 2.25

15, NR, 12.58 ± 3.08

Picture-naming task

Intensity and duration of speech

Utterance duration: ASD > TD

No statistical difference for intensity was found

Hubbard et al. (2017)²¹

15, 15, 27 (21–42)

15, 15, 21 (18–26)

Evoked elicitation procedure for prosodic production for different emotional context

F0 range and voice intensity

Intensity and F0 range: ASD > TD

Hubbard and Trauner (2007)⁵³

9, 6, 14.5

10, 9, 14.5

Repeat type recorded contents with different intonation

Frequency, amplitude, and duration measurements of recorded speech

ASD exhibited lower pitch peak location accuracy compared with TD

Pitch range: ASD > TD

Hudenko et al. (2009)⁵⁴

15, 13, 9.1 ± 0.77

15, 13, 9 ± 0.7

Laugh elicitation

Duration, F0, F0 variability

All acoustic measures were not significant, with the exception of the comparisons between voiced and unvoiced laughter

Kaland et al. (2013)⁵⁵

20, 14, 28.9

20, 3, 21.8

Communication task

Pitch analysis

F0 range: ASD < TD

Lehnert-LeHouillier et al. (2020)¹⁴

12, 3, 12.14 ± 1.84

12, 3, 12.23 ± 1.89

Conversation

Acoustic analysis of a goal-directed conversation task, conversational F0 range

F0 range: ASD > TD

Patel et al. (2020)¹⁸

55, 45, 16.57 ± 6.62

39, 19, 18.99 ± 5.21

Narration elicitation using a wordless picture book

Mean, range and standard deviation of F0, speech rate, speech rhythm using normalized PVI

F0 variability: ASD > TD

Lyakso et al. (2016)³⁷

25, x, 5–14

60, NR, NR

Emotional speech, spontaneous speech, and the repetition of words

Pitch values, max and min values of pitch, pitch range, formants frequency, energy and duration of recorded voice and speech

Pitch values of spontaneous speech: ASD > TD

Nadig and Mulligan (2017)⁵⁶

9, 1, 5.72 ± 1.00

9, 5, 3.065 ± 0.59

Audio stimuli

Mullen scales of early learning for assessing cognitive functioning for receptive and expressive language

ASD and TD groups were not significantly different for repetition accuracy

ASD group had higher score for accurate repetition for four syllables

Nadig and Shaw (2012)²⁹

15, 13, 11 ± 0.791

13, 11, 11 ± 2

Conversation task

Pitch range

Pitch range: ASD > TD

Nadig and Shaw (2015)⁵⁷

15, 12, 5.5 ± 1.42

11, 2, 5.66 ± 1.9

Describe a target object

Amplitude, duration and mean pitch

Intensity: ASD < TD

Duration: ASD > TD

Nakai et al. (2014)²⁶

20, 15, 7.9 ± 0.7

21, 10, 7.9 ± 0.1

Picture-naming task

F0 and pitch

Greater pitch variability: ASD > TD

Nayak et al. (2019)³⁸

16, 11, 7–18

27, 16, 7–18

General communication

Mean pitch, pitch range, and the standard deviation of pitch

Pitch variability: ASD < TD

Ochi et al. (2019)⁵⁸

62, 62, 26.9 ± 7.0

17, 17, 29.6 ± 7.0

General conversation

log F0, intensity, and speech rate; mean and standard deviation for pitch and intensity over the whole session

Standard deviation of intensity: ASD < TD

Olivati et al. (2017)²³

19, 19, 13.37 ± 6.12

19, 19, NR

Speech-language pathology screening for vocal quality, speech chain, comprehension of simple and complex orders

F0, intensity and duration of recorded voices

Maximum and minimum intensity and distance between maximum and minimum F0 frequencies: ASD > TD

Duration: ASD > TD

Paul et al. (2008)¹⁶

46, 43, 13.2 ± 4.4

20, 17, 7.91–27.42

Constrained production (imitation)

Duration

Stressed syllable duration : ASD < TD

Patel et al. (2020)¹⁸

55, 45, 16.57 ± 6.62

39, 19, 18.99 ± 5.21

Narration

Mean pitch, speech rate

Speech rate: ASD < TD

Quigley et al. (2016)⁵⁹

10, 5, 12.12 ± 0.89

9, 5, 11.95 ± 0.84

Mother–infant social interaction

Mean F0, pitch range and intensity

No significant differences were found between groups

Scharfstein et al. (2011)⁶⁰

30, 26, 10.57 ± 1.6

30, 22, 10.60 ± 2

Conversation

Pitch and intensity

Mean vocal intensity: ASD < TD

Sharda et al. (2010)⁶¹

15, 14, 6.25 ± 1.5

10, 9 , 7.3 ± 2

Spontaneous speech task

Pitch and pitch range

Pitch, pitch range: ASD > TD

Sheinkopf et al. (2012)⁶²

21, 15, 0.5 ± 0.5

18, 8, 0.5 ± 0.5

Audio–video recordings at 6 months of age of participants and Identification of cry episodes

F0 and phonation

F0 for cry: ASD > TD

Unwin et al. (2017)⁶³

22, 18, 1

27, 12, 1

F0, Amplitude, first and second formants (F1, F2), Cry duration

Cry duration: ASD < TD

Van Santen et al. (2010)¹⁷

22, NR, 6.35 ± 1.02

22, NR, 6.57 ± 1.29

Lexical stress task

F0, amplitude and duration

F0: ASD > TD during lexical stress task

Wehrle et al. (2020)³⁹

14, 10, 42.5 ± 7.8

14, 11, 37.3 ± 8

Semi-spontaneous speech in the form of task-oriented dialogues

Pitch range, mean F0

ASD group shows more melodic or singsongy intonation style