**Study Information** **Hypotheses** The study will test 4 hypotheses, outlined below as H1, H2 (a1 & a2, b1 &b2), H3 (a & b) and H4 (a&b). Our predictions are based on the existing literature on parent language intervention and its effect on parent-child interactions, as well as on infant-directed speech (IDS). The overall finding from this literature is that raising parents’ awareness about child language development has a positive impact on parents’ quantity and quality of interaction with their child (e.g., Suskind et al., 2015; Ferjan Ramírez et al., 2020; Huber et al., 2023), as well as on the conversational turns between parent and child (Ferjan Ramírez et al., 2019; 2020). Previous research suggests that parents intuitively adapt their speech when engaging with their child by using higher pitch, wider pitch range, slower articulation rate and elongated vowel duration (e.g., Benders et al., 2021; Leong et al., 2014; Englund & Behne, 2006; Rosslund et al., 2022; Cox et al., 2022; Soderstrom, 2007; Fernald et al., 1989; Dunn & Kendrick, 1982; Jacobson et al., 1983). Changes in parents’ attitude towards language H1) We expect that changes in the EPAQ in the parental attitudes and beliefs about language development in children and parents’ role in infants’ language development will be observed in the parents in the intervention group but not in the ones in the active control group. Specifically, after the intervention, parents from the intervention group would agree more strongly (Likert Scale 3, 4, 5, 6) with statements that favour IDS. On the other hand, deprecative statements are expected to be rated as less approving (Likert scale 0, 1, 2, 3). This aligns with previous research which observed that language-focused interventions led to an increase in parental engagement in the language development of their child (Leffel & Suskind, 2013; Suskind et al., 2015). Changes in the quantity and quality of IDS H2) We expect that there will be differences in the quantity and quality of IDS between the intervention group and the control group and these differences will increase with age (over the course of the intervention). Quantity of IDS a1) In terms of quantity, it is predicted that the amount of language input that the parents in the intervention group provide their children with will be higher as compared to the control group. An increase in parental input directed to the child and in IDS in parents receiving coaching have been found in previous research (Ferjan Ramírez et al., 2019). a2) We expect that, as the intervention unfolds, the differences between the intervention and the control group will grow through the effect of age/meetings. Our hypothesis is based on Ferjan Ramírez et al.’s (2019) findings of a significant time by group interaction, resulting in parents from the intervention group displaying greater increases in parents’ speech directed to their child across age compared to the control group. Quality of IDS b1) For the quality of IDS specifically, a higher mean pitch of the voice and a wider pitch range are predicted in parents in the intervention group compared to those in the control group. Parents’ modifications of speech have been noticed in previous research (Rosslund et al., 2024; Fernald & Simon, 1984; Stern et al., 1983; Fernald & Kuhl, 1987; Fernald et al., 1989; Cox et al., 2022; Cox et al., 2023; Cristia, 2013). b2) Similarly to hypothesis 2a2), we predict that the differences in the quality of IDS (pitch and pitch range) between the intervention and the control group grow as the intervention unfolds. This aligns with Ferjan Ramírez et al. (2019; 2020), who observed that the percentage of IDS increased more across time in parents in the intervention group compared to those in the control group. Parent-child interactions H3) a) We expect that the parent-child interactions will be more dynamic in the intervention group - in terms of the number of turn-taking interactions/ conversational turn count (CTC) - meaning that parents in the intervention group will give their child more opportunities to participate in the verbal exchange than the parents in the control group. It was found that more frequent parent-child conversational turns are associated with an augmented language development (Tamis-LeMonda et al., 2001; Hoff, 2006) and improved socioemotional competencies (Gómez Muzzio & Strasser, 2021).This aligns with previous research that suggests that parent coaching has a positive effect on conversational turns and parental use of parentese speech (Ferjan Ramírez et al., 2019; 2020; Leech & Rowe, 2020). b) We predict that the age/meetings effects will lead to bigger differences in parent-child interactions between the intervention group and the control group. In other words, with time unfolding, the intervention group will increase their parent-child interactions more than the control group, leading to a bigger gap between both groups. Previous research suggests that a significant interaction between group and time could be observed in parent-child interactions, meaning that families from the intervention group showed a more dominant increase in parent-child interactions than the control group families (Ferjan Ramírez et al., 2020). Relation between parents’ attitudes and beliefs and their IDS H4) a)We expect that a positive relationship between parents’ attitudes towards child language development and towards their impact on children’s language development and their linguistic input can be observed at the beginning and at the end of the intervention. Specifically, we expect that parents who agree more with positive attitudes and beliefs about language development will offer increased quantity and quality of linguistic input, as well as more frequent turn-taking during parent-child interactions. As an example, a strong agreement with the statement ‘When talking to a young child I often use a different voice with a more lively tone’ (EPAQ 27) indicates parents’ awareness of their parent-child interaction and suggests that (H2) they also implement the latter in real life by using higher pitch and wider pitch range. b) With regards to the effect of time on the relationship between parents’ attitudes and behaviour, we expect that, as the intervention unfolds, positive changes in parents’ language attitudes and beliefs (H1) are related to an increase in IDS quantity (H2), IDS quality (H2), and parent-child turn-taking (H3). Based on (H1), this relationship would be observable in the intervention group and not in the control group since no changes in the EPAQ are expected in the control group. If (H1) shows not to be supported and changes would be observed in the control group, the relationship between positive changes (H1) and IDS quantity, quality (H2), and parent-child turn-taking (H3) would be greater in the intervention group than in the control group. This stronger relationship in the intervention group would be based on (H2) and (H3), which expect that increases in IDS quantity, quality, and parent-child turn-taking will be greater in the intervention group than in the control group. **Design Plan** **Study Type** Experiment - A researcher randomly assigns treatments to study subjects, this includes field or lab experiments. This is also known as an intervention experiment and includes randomized controlled trials. **Blinding** For studies that involve human subjects, they will not know the treatment group to which they have been assigned. **Additional Blinding** No **Study Design** The study is a longitudinal within- and between-subject two-group design with repeated measures. Parental attitudes towards and beliefs about language development in children and parents’ role in infants’ language development were collected through an online questionnaire (EPAQ; Hembacher & Frank, 2020) that was specifically adapted to Norwegian for the study (Allegretta et al., in press). All parents from both the intervention and the control group filled out the questionnaire when their child was 2 and 12 months of age. The EPAQ is composed of a Likert scale on which parents have to choose how they agree with a given statement (0 - strongly disagree, 6 - strongly agree). The EPAQ was adapted prior to the study, as well as translated into the 7 most spoken languages in the district of Stovner, Oslo (Norwegian, English, Urdu, Somali, Arabic, Polish, Tamil). The 24 questions included basic demographic data, the child’s language learning surrounding and parental beliefs about parenting. The three main categories of the EPAQ consisted of 8 questions each and addressed Affection and Attachment, Early Learning, and Rules and Respect. Additionally, the questionnaire integrated the following 4 statements that focused on parents’ attitudes and beliefs about IDS: ‘I talk to babies and young children in the same way I talk to adults.’ (EPAQ 25), ‘I automatically use ‘baby language’ (for example words like “peep-peep” or “woof-woof”) when talking to a young child.’ (EPAQ 26), ‘When talking to a young child I often use a different voice with a more lively tone.’ (EPAQ 27), and ‘When talking to a young child I often speak more slowly and clearly.’ (EPAQ 28). As the main caregiver, mothers and their child from the intervention group were invited to attend individual meetings of 20-30 minutes. During the individual meetings, they received information from a specialist in Norwegian or English or by an interpreter if another language was needed for communication. Mothers and their child from both the intervention and the control group were invited to group meetings of 30-40 minutes at the open kindergarten. At group meetings, 4-5 mothers with their children gathered to talk about and practice the real-world application of the topics covered at the individual meetings. As an example, for the topic of Baby songs, participants would learn about different types of songs that they can sing to their children, and the specialist introduces them to some local Norwegian songs. Mothers in the intervention group were invited to 2 individual meetings at 4 and 8 months of age of the child and to 2 group meetings at 6 and 10 months of age. The intervention group received information from a language specialist about parental input, infant language development and the role of parental speech in language development. The topics of the group sessions were ‘Baby and Song’, and ‘Baby and Books’. Additionally, there were 2 more individual meetings at 16 and 24 months, and another group meeting at 14 months, focusing on Play and Vocabulary. The control group did not have individual meetings but 2 group meetings at 4 and 8 months of age of the child with a focus on infant motor development and other domains such as ‘Baby and Crying’, and ‘Sensory/ Fine Motor Skills’. Similarly to the intervention group, there was another group meeting at 16 months, targeting Gross Motor Skills. The control group was also invited to an individual meeting at 24 months of age. For the assessment of the quantity and quality of IDS and parent-child interaction, the mothers were invited to naturally engage with their child during a 10-20 minutes open play session at the Stovner open kindergarten when the child was 8 and 12 months old. Note that due to the ongoing collection of data and the time constraints of the Master’s thesis, only the EPAQ at 2 and 12 months, as well as the audio recordings at 8 and 12 months will be analysed. Since this study is part of a longitudinal project, parents filled out the EPAQ at 2, 12 and 24 months of age. The audio recordings took place when the child was 8, 12, 16 and 24 months old. Data from EPAQ at 24 months and from the audio recordings at 16 and 24 months would not be yet fully collected at the time of processing and analysing the data for the MA thesis. For the same reasons, vowel duration, articulation rate and children’s language skills (i.e., babbling, word comprehension and production) will not be extracted from the audio recordings and analysed. **Randomization** Parents were randomly assigned to either the experimental group or the active control group. The randomisation technique used in this study was simple randomisation. **Sampling Plan** **Existing Data** Registration prior to analysis of the data. **Explanation of Existing Data** By the time of the preregistration, part of the data has been processed such as the EPAQ data at 2 months of age of the child, but not analysed, while the remaining part of the data is still being collected with the study being a longitudinal project. During a pilot study, the data from the EPAQ was considered but no analyses were performed. **Data Collection Procedures** Participants were recruited at the local Health Station of Stovner, a city district in Oslo in Norway with the highest rate of immigrants in Norway with the proportion of new-borns with an immigrant background reaching 80% as of 2017 (Statistics Norway, 2023). Having a multi-ethnic, multicultural and multilingual background, many children in Stovner can be seen as vulnerable because of their immigrant status, potentially being less integrated in society and parents not speaking Norwegian or English, which inhibits their access to public services. Stovner displays Oslo’s lowest levels of kindergarten attendance with 27.4% of 1-5-year-old children in Stovner never attending kindergarten, and many families have low SES and low educational levels (Statistics Norway, 2023). The health secretaries sent out a message via Helsenorge when the baby was around 2 months of age. The invitation to participate in the study informed parents about the research project, and provided a link to more information, the consent form, and the sign-up questionnaire. At the 3-months follow-up appointment at the Health Station, the family received a reminder about the project by the health secretary or health nurse and also the link to essential documents. The consent form was filled out by the mothers, identified as the main caregivers. Parental attitudes towards and beliefs about language development in children and parents’ role in infants’ language development were collected through the online EPAQ that was specifically adapted for the study (see section ‘Study design’). After the completion of each online questionnaire, the parents received a gift card and throughout the project, they also received several gifts for their child. For the assessment of the quantity and quality of IDS and parent-child interaction, the mothers, as the main caregivers, were invited to engage naturally with their child during a 10-20 minutes open play session at the Stovner open kindergarten when the child was 8, 12, 16 and 24 months old. **Sample Size** The first 25 participants were selected from the data of the main longitudinal project, which contains 40 participants in total. **Sample Size Rationale** Only the first 25 participants born between May 2023 and March 2024 were selected due to the time constraints of the MA thesis. This allows the EPAQ and audio recording data collection to be completed by the end of March 2025, and thereby enabling enough time to conduct the data analyses. **Stopping Rule** See above. **Variables** **Manipulated Variables** Independent variables: -Group Assignment (Between-Subjects Variable): Levels: Intervention Group & Control Group **Measured Variables** **Dependent Variables** EPAQ measures: For the Master’s thesis, a subset of 5 statements of the EPAQ (statements 9 & 13 (Talking to children & Book reading) & 25, 27, & 28 (IDS)) will be used that specifically focus on parents’ attitudes towards Talking to children, Book reading, and parents’ beliefs about IDS. There will be 3 variables of EPAQ: Question 9 will be a separate variable about Talking to children (variable 1), Question 13 will be a separate variable about Book reading (variable 2), and Questions 25, 27 and 28 will be regrouped into one variable focusing on the quality of IDS (variable 3). Before being able to regroup EPAQ questions 25, 27 and 28 into the composite score ‘IDS’, a factorial analysis will be performed to see if the 3 questions align together. These questions will be processed for both intervention and control groups. EPAQ_IDS => EPAQ scores on statements 25, 27, and 28 at 2 and 12 months Please note that statements that do not align with the favouring of the constructs of Talking to Children, Book Reading and IDS will be reverse-scored. Higher scores are assigned to statements that favour the constructs, meaning that contradicting statements will be reverse scored: Revised Score = Maximum Possible Score - Original Score. For example: if the statement ‘I talk to babies and young children in the same way I talk to adults’ (EPAQ 25) was ranked as 0 (strongly disagree), the reversed score = 6 - 0 = 6. H1: Changes in Parents’ Language Attitudes EPAQ_TalkingtoChildren => EPAQ scores in Talking to children at 2 and 12 months EPAQ_BookReading => EPAQ scores in Book reading at 2 and 12 months EPAQ_IDS => EPAQ scores in IDS at 2 and 12 months H2: Quantity and Quality of IDS (a) Quantity of parental input at 8 and 12 months in both groups: Proportion of language input directed to child at 8 and 12 months, in both intervention and control groups It will be computed as the proportion of parent speech time in total length of recording. Proportion_language_input => Proportion of language input (parentese or standard speech) from the mother directed to the child (b) Quality of parental input at 8 and 12 months in both groups: To examine the acoustic differences between the intervention and the control group, the below mentioned variables will be analysed across the audio segments of phrases extracted from the recordings using Praat software. To identify and segment phrases, the study follows Rosslund et al.’s (2022; 2024) approach: A phrase is identified as a segment of continuous speech separated by at least 500ms of silence. An automated procedure in R (101), using the word tier from the textgrids generated by forced alignment, will be used to extract phrases. The word tier will be transformed into an organised R dataframe by using the ‘tier_to_df’ function from the R package phonfieldwork (version 0.0.11 (102)). The word tier will include word portions accompanied by the pauses between contiguous words. A systematic examination of each word will be conducted, and words with pauses between them shorter than 500ms (as used in, e.g. Benders et al. (2021) & Rosslund et al. (2024)) will be identified and merged into a single phrase. The length and the subject matter of a phrase will differ across portions, ranging from short utterances to full sentences. A tailored Praat script (Hirst, 2012) will extract the minimum, maximum, and mean pitch (F0) in Hz by default for each phrase. Since pitch perception operates on a logarithmic scale, a conversion of all Hz values to semitones will be performed, following the formula used by Kalashnikova and Burnham (2018): semitones = 12 x log^2(F0/constant), with a constant of 10 (i.e., semitones above 10 Hz). Mean pitch (semitones): Pitch of parental speech in each segmented phrase: Pitch => the voice’s tonal height, marked by vocal fold vibrations, and evaluated as the mean fundamental frequency (transformed to semitones) across a phrase (Rosslund et al., 2024). Pitch range (semitones): Difference between maximum and minimum pitch in each segmented phrase: PitchRange => the tonal spectrum of the voice, evaluated as the difference between the highest and the lowest pitch values within a phrase. H3: Parent-Child Interaction Turn-Taking Parent-child interactions: Number of Turn-Taking Interactions at 8 and 12 months in both groups: The number of turn-taking interactions will be measured based on the number of parent-child CTC in relation to the length of the recording. Phrases (segmented by Praat as specified above) that are followed by a child vocalisation will be counted and defined as a CT. The maximum latency between the parental phrase and the child vocalisation is a 5-s pause (Gilkerson et al., 2017). This 5-s threshold after the parent’s phrase acts as an inclusion criteria that allows it to identify the conversational turns that qualify as immediate conversational turn-taking. This prevents counting child’s vocalisations that are delayed beyond a typical response time. CTC => conversational turn count H4: Relation between parents’ attitudes and beliefs and their IDS The following measures are baseline-corrected as described below: Baseline-corrected Measure = (Measure at Time 2 - Measure at Time 1) / Measure at Time 1 Overall Difference between Intervention and Control Group in Changes of EPAQ: EPAQ_change => difference between the EPAQ scores at 12 and 2 months for the Items TalkingtoChildren, BookReading, and IDS while accounting for the EPAQ score at 2 months. Positive scores will indicate that attitudes and beliefs are more in favour of Talking to Children, more Book Reading and better IDS. Change of Proportion of language input between 8 and 12 months within Intervention and Control Groups: Proportion_language_input_Change => difference in proportion of language input at 12 and 8 months while accounting for proportion of language input at 8 months. Positive scores will indicate that Proportion of Language input increases between 8 and 12 months. Change of Pitch between 8 and 12 months within Intervention and Control Groups: Pitch_Change => difference in pitch between Pitch at 12 months and 8 months while accounting for Pitch at 8 months. Positive scores will indicate that Pitch increases between 8 and 12 months. Change of Pitch Range between 8 and 12 months within Intervention and Control Group: Pitch_Range_Change => difference between Pitch Range at 12 months and 8 months while accounting for Pitch Range at 8 months. Positive scores will indicate that Pitch Range increases between 8 and 12 months. Changes of CTC between 8 and 12 months within Intervention and Control Group: CTC_Change => difference between CTC at 12 months and 8 months while accounting for CTC at 8 months. Positive scores will indicate that CTC increases between 8 and 12 months. **Indices** *No response* **Analysis Plan** **Statistical Models** The following statistical models will be used to test our hypotheses: Differences and Changes in the attitudes and beliefs about Early Learning and IDS between the Intervention and Control groups H1) We expect overall more positive attitudes towards and beliefs about language development in parents in the intervention group compared to the control group due to bigger positive changes from 2 to 12 months. 1.To assess differences in parental language attitudes between the intervention and control groups over two time points (2 and 12 months), we will use mixed-effect regression models with the outcome measures being EPAQ_TalkingtoChildren, EPAQ_BookReading, and EPAQ_IDS. Group (intervention/control), time (2 and 12 months), and their interaction will be fixed effects. Socio-economic status (indexed via mother’s highest education) and the gender of the child will be covariates. To factor in the random variability between individual participants, (1| Participant_ID) will be used as a random effect. Before being able to regroup EPAQ questions 25, 27 and 28 into the composite score ‘IDS’, a factorial analysis will be performed to see if the 3 questions align together. The models for H1 are specified below: (a) EPAQ_TalkingtoChildren ~Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status (b) EPAQ_BookReading ~Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status (c) EPAQ_IDS ~Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status Quantity of IDS H2) We expect that the amount of input that the parents in the intervention group provide their children with, is overall higher and increases over time more in comparison to the control group. 1.To assess the quantity of IDS, we will use a mixed-effect regression model with the outcome measure being the Proportion of language input, extracted from parental speech recordings. Fixed effects will include group (intervention/control), time (8 and 12 months), and their interaction. Socio-economic status (indexed via mother’s highest education) and the gender of the child will be covariates. To factor in the random variability between individual participants, (1| Participant_ID) will be used as a random effect. (a) Proportion_language_input ~Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status Changes in the Quality of IDS H2) We expect that the quality in IDS will increase over time in the intervention group compared to the control group, specifically, we expect an overall higher pitch and pitch range in the intervention group and larger increase in pitch and pitch range over time. 1.To test differences in IDS quality, separate linear mixed-effects models will be performed for the following outcome measures: Pitch and Pitch Range. Group (intervention/control), time (8 and 12 months), and their interaction will be fixed effects. Socio-economic status (indexed via mother’s highest education) and the gender of the child will be covariates. To factor in the random variability between individual participants, (1+ Time| Participant_ID) will be used as a random effect. (a) Pitch ~Time + Group + Time : Group + (1 + Time| Participant_ID) + child_gender + socio_economic_status (b) Pitch_Range ~Time + Group + Time : Group + (1 + Time| Participant_ID) + child_gender + socio_economic_status Changes in Parent-Child Turn-Taking H3) We expect that the parent-child interactions in the intervention group will feature more frequent conversation turn-takes between the parent and the child, than in the control group. 1.To assess changes in turn-taking, we will conduct a mixed-effect regression model with CTC being the outcome measure. Group (intervention/control), time (8 and 12 months), and their interaction will be included as fixed effects. Socio-economic status (indexed via mother’s highest education) and the gender of the child will be covariates. To factor in the random variability between individual participants, (1| Participant_ID) will be used as a random effect. (a) CTC ~ Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status Relation between parents’ attitudes and beliefs and their IDS H4) a)We predict a positive concurrent relationship between parents’ attitudes towards child language development and their linguistic input (quantity, quality, turn-taking) at both the beginning and at the end of the intervention. 1.To assess this hypothesis, several mixed effect regression models will be run with the outcome measures being each of our IDS measures (quantity, quality, turn-taking), namely Proportion_language_input, Pitch, Pitch_Range and CTC. Talking to Children, Book Reading, IDS and Time (8 and 12 months) will be fixed effects, along with the interaction between Time and each of Talking to Children, Book Reading and IDS. Socio-economic status (indexed via mother’s highest education) and the gender of the child will be covariates. To factor in the random variability between individual participants, (1| Participant_ID) will be used as a random effect. (a) Proportion_language_input ~ EPAQ_TalkingtoChildren + EPAQ_BookReading + EPAQ_IDS + EPAQ_TalkingtoChildren : Time + EPAQ_BookReading : Time + EPAQ_IDS : Time + Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status (b) Pitch ~ EPAQ_TalkingtoChildren + EPAQ_BookReading + EPAQ_IDS + EPAQ_TalkingtoChildren : Time + EPAQ_BookReading : Time + EPAQ_IDS : Time + Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status (c) Pitch_Range ~ EPAQ_TalkingtoChildren + EPAQ_BookReading + EPAQ_IDS + EPAQ_TalkingtoChildren : Time + EPAQ_BookReading : Time + EPAQ_IDS : Time + Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status (d) CTC ~ EPAQ_TalkingtoChildren + EPAQ_BookReading + EPAQ_IDS + EPAQ_TalkingtoChildren : Time + EPAQ_BookReading : Time + EPAQ_IDS : Time + Time + Group + Time : Group + (1| Participant_ID) + child_gender + socio_economic_status b)Moreover, we expect that positive changes in parents’ language attitudes and beliefs (H1) are related to an increase in IDS quantity (H2), IDS quality (H2), and parent-child turn-taking (H3), especially in the intervention group. 1.Several mixed effect regression models will be performed with the outcome measures being each of our IDS measures (quantity, quality, turn-taking, respectively), namely Proportion_language_input_Change, Pitch_Change, Pitch_Range_Change and CTC_Change. Talking to Children Change, Book Reading Change, IDS Change and Group (interaction/control) will be the fixed effects, along with the interaction between Group and each of Talking to Children Change, Book Reading Change and IDS Change. Socio-economic status (indexed via mother’s highest education) and the gender of the child will be covariates. (a) Proportion_language_input_Change ~ TalkingtoChildren_Change + BookReading_Change + IDS_Change + TalkingtoChildren_Change : Group + BookReading_Change : Group + IDS_Change : Group + Group + child_gender + socio_economic_status (b) Pitch_Change ~ TalkingtoChildren_Change + BookReading_Change + IDS_Change + TalkingtoChildren_Change : Group + BookReading_Change : Group + IDS_Change : Group + Group + child_gender + socio_economic_status (c) Pitch_Range_ Change ~ TalkingtoChildren_Change + BookReading_Change + IDS_Change + TalkingtoChildren_Change : Group + BookReading_Change : Group + IDS_Change : Group + Group + child_gender + socio_economic_status (d) CTC_Change ~ TalkingtoChildren_Change + BookReading_Change + IDS_Change + TalkingtoChildren_Change : Group + BookReading_Change : Group + IDS_Change : Group + Group + child_gender + socio_economic_status **Transformations** Statements on the EPAQ opposing Talking to children, Book reading or IDS will be reverse-coded. Higher scores are assigned to statements that favour the constructs, meaning that contradicting statements will be reverse scored: Revised Score = Maximum Possible Score - Original Score. For example: if the statement ‘I talk to babies and young children in the same way I talk to adults’ (EPAQ 25) was ranked as 0 (strongly disagree), the reversed score = 6 - 0 = 6. There will be 3 variables of EPAQ: Question 9 will be a separate variable about Talking to children (variable 1), Question 13 will be a separate variable about Book reading (variable 2), and Questions 25, 27 and 28 will be regrouped into one variable focusing on the quality of IDS (variable 3). The categorical variable Group will be dummy coded (Control = 0, Intervention = 1). Time will also be dummy coded. For the EPAQ data: time points: 2 months (T1 = 0) and 12 months (T2 = 1); for the audio recordings data: time points: 8 months (T3 = 0) and 12 months (T4 = 1). Since pitch perception operates on a logarithmic scale, a conversion of all Hz values to semitones will be performed, following the formula used by Kalashnikova and Burnham (2018): semitones = 12 x log^2(F0/constant), with a constant of 10 (i.e., semitones above 10 Hz). If necessary, the acoustic measures (pitch, pitch range) will be log-transformed in the case of skewness in the data distribution. Additionally, other predictor or dependent variables might be transformed in case of high skewness, and if transformation of the variable improves homogeneity and normality of residuals, or minimises leverage issues that could be identified in the model otherwise. **Inference Criteria** We will use p-values and R-squared to qualify the significance and magnitude of our results, to deduce whether there are differences between the intervention and control group in parental language attitudes, IDS quantity and quality and turn-taking as well as whether differences in parental language attitudes in the intervention vs control group predict IDS quantity and quality, as well as turn-taking. **Data Exclusion** The following criteria will be used to exclude participants: an infant was born premature (before week 37 of gestation) or the infant exhibited auditory or visual impairments. Samples where no auditory input or masked by a lot of noise or not displaying a visible burst in the spectrogram or waveform were excluded from the analyses because it would prevent the reliable detection of language input from the caregiver. Additionally, for pitch, adult phrases with mean F0 values below 60 Hz and/or above 600 Hz will be excluded since these frequencies are beyond possible adult range. Similarly for pitch range, the exclusion criteria depends on the exclusion criteria of pitch. For CTC, latencies of above 5s (Gilkerson et al., 2017) between the parental phrase and the child vocalisation will act as exclusion criteria. **Other** **Other** The study is part of a longitudinal project, with the same participants, on the role of parents’ awareness of children’s language development on the quantity and quality of parental input, parent-child turn-taking, the development of the child’s babbling, word comprehension and production. 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