1.Introduction

Autism Spectrum Disorder (ASD) is a serious neurodevelopmental condition characterised by difficulties with social communication, repetitive behaviours, constrained interests, as well as deficits in expressive or receptive language skills [1]. Music therapy, among other evidence-based therapies, is beneficial in helping autistic people with their interpersonal difficulties and language skills [2]. The use of music therapy in treating autistic populations is anchored in numerous conceptualisations (e.g., sensory-perceptional, developmental, creative, behavioural) and is achieved through a variety of strategies (e.g., songwriting, instrument play, movement) [3]. Three approaches of music therapy developed in recent years attract attention.

Auditory Motor Mapping Training (AMMT) is an intonation-based intervention that aims to enhance speech production by helping autistic children establish relations between particular sounds and articulatory motions [4]. Target words and phrases are presented by simultaneously intoning and tapping the drums to facilitate auditory-motor mapping, and meanwhile, prosodic elements are emphasised in the treatment to enhance right hemisphere functions [5].

Another widely applied model of intervention practice featuring musical elements is Family-Centred Music Therapy (FCMT). It was first put forward by Grace Thompson [6] based on previous studies on music therapy with families and her own experience of thirteen years of practice. This model prioritises collaboration between parent and therapist and encourages active participation of the parent as integration of broad principles combined into music therapy including family-centred practice, relationship-oriented techniques, and natural settings [6].

The third approach, Melodic Based Communication Therapy (MBCT), is a speech therapy first established by Givona Sandiford with the goal of improving verbal output in autistic children by utilizing their presumptive musical talents [7]. It is characterized by (a) pre-established pairing of fixed melody with target words, (b) standardised procedure and tailored reinforcement schedule, and (c) involvement of clapping and rhythm [7].

While there is increasing evidence that these three approaches can improve communication abilities, speech production, and social abilities in young autistic population [8], no studies have yet systematically analysed the efficacy of these three approaches. The current study aims to: (a) conduct a comprehensive review of all existing studies assessing the effectiveness of these three approaches, and (b) systematically analyse them in terms of their respective outcomes and overall effectiveness.

2.Materials and Methods

2.1.Search Strategy

This review was carried out in accordance with the PRISMA recommendations [9]. Major electronic databases including Web of Science, Cochrane, PubMed, and EBSCO databases were searched to identify relevant articles. The search terms were: (a) “autism OR autism spectrum disorder OR ASD OR autistic children OR autistic disorder” AND (b) “auditory-motor mapping training OR AMMT OR melodic based communication training OR MBCT OR family centred music therapy OR FCMT” AND (c) “music OR music therapy.” The search was restricted to research that appeared in peer-reviewed publications between January 1980 and May 2023.

2.2.Inclusion Criteria

The pre-specified inclusion criteria were based on the PICOS framework (see Table 1), with others.

Table 1: Eligibility criteria.

2.3.Study Selection and Data Extraction

This section must be in one column. During the database search process, 56 possibly eligible publications were found in total. After removing duplicates, 32 articles were left. Following a check of each article’s title and abstract using the aforementioned inclusion and exclusion criteria, 13 articles were selected for full-text reviews. All 13 articles were read through and 11 of them were screened as eligible ones (see Figure 1).

Figure 1: Literature search flow chart according to PRISMA.

2.4.Data Analysis

After the study specifics were extracted, the articles were organised thematically depending on the methodology used (see Table 2, 3, and 4).

2.5.Risk of Bias Assessment

The technique developed by the Cochrane Collaboration was used for risk of bias assessment [19]. Each item for the studies included was examined and then classified as “low,” “high,” or “unclear” (see Figure 2).

Figure 2: Risk of bias assessment of included studies.

3.Results

3.1.Characteristics of the Included Studies

In all studies included, the sample sizes were small to medium, with 2 to 30 participants, predominantly nonverbal or minimally verbal autistic children aged between 3 and 9 years. One study [13] diverged from this demographic, comparing the efficacy of treatment on a more-verbal child with a minimally verbal child. The treatment duration varied between 2 to 24 weeks (M=9±7.16), with participants receiving 4-30 hours (M=14±8.11) of treatment and treatment frequencies ranging from 5 times a week to once every two weeks. Most studies were conducted in English (N=8), while three studies were conducted in Korean [10], Chinese [14], and Greek [17] respectively.

3.2.Effect of AMMT on Autistic Children

Studies have demonstrated that AMMT can enhance autistic children’s overall speech production and responsiveness [4,10-13,15]. Typically, significant improvements in the production of syllables, vowels, and consonants can be achieved after 18 to 19 hours of treatment.

According to Wan et al. [4], after AMMT, all children had noticeably improved in word and phrase understanding, with generalisation to things that were not practised in therapy. Chenausky et al. [12] found that the AMMT group considerably outperformed the Speech Repetition Therapy (SRT) control group in terms of Percentage Syllables Approximated and Percentage Consonants Correct. Additionally, in a further study [13], they compared the efficacy of AMMT in minimal verbal children and a more-verbal child, revealing that the more-verbal participant with ASD exhibited significantly larger effect sizes in terms of improvements. Massey [11] conducted a study that was similar to Wan et al. [4], and found an increase (yet not significant) in overall speech production (p = .424) and the development of pre-linguistic gestures (p = .063) after twelve 20-min bi-weekly AMMT sessions.

Two studies investigated AMMT in languages other than English [10,14], yet one of them yielded statistically insignificant outcome [10], probably due to limited invention time (4.5h in total). Despite of statistical insignificance, the author did find overall growth in word production in children with ASD after AMMT performed in Korean. The other study investigated the effect of AMMT compared to SRT in nonverbal and minimal verbal native Chinese autistic children and found that for minimal verbal individuals, AMMT better accelerates the rate of progress in speech production; however, for nonverbal individuals, the responsive rate is extremely low (one out of six), and all participants showed no progress under both treatments [14]. This outcome is inconsistent with the other studies. Since no other studies have investigated AMMT in Chinese, further research and more data are necessary to draw valid conclusions.

3.3.Effect of FCMT on Autistic Children

The effectiveness of FCMT in autistic children was investigated in two studies. Results showed that in contrast to conventional early childhood intervention, the parent-child bond and social interactions in home and community were improved by FCMT, but linguistic abilities and general social responsiveness were not [16].

Vaiouli and Andreu [17] expanded the use of FCMT to Greek and examined its effects on preverbal and verbal communication abilities of young autistic children. They found that FCMT improved preverbal communicative actions, such as eye-gaze, gestures, and sounds, and facilitated interaction and meaningful engagement in social activities between parents and their children.

3.4.Effect of MBCT on Autistic Children

Two studies by Sandiford [6,18] showed notable effectiveness of MBCT on speech production and pragmatics in nonverbal autistic children. The therapy was found to be more efficient than conventional speech and language therapy at eliciting speech in participants and helping them transfer newly acquired abilities to real-world situations. Additionally, the study showed that MBCT was also successful in enhancing pragmatics, exhibiting its promise as a strategy for enhancing social language abilities in autistic children.

4.Discussion

The goal of this study was to systematically review and analyse the existing literature on the effects of three music therapy techniques in autistic children, namely AMMT, FCMT, and MBCT. This review summarized and analysed studies examining the efficacy of the three approaches, providing general and detailed information on the current research status for future studies. This review shows that (a) all three approaches have positive impact on children with ASD, and that (b) enhancement brought by the three approaches lie in different aspects, with AMMT mainly improving speech production, FCMT encouraging communication and strengthening family relationship, and MBCT refining social language skills. This diversity in improvements indicates the possibility of combining the three approaches to yield better outcomes in autistic children.

Check that in line drawings, lines are not interrupted and have a constant width. Grids and details within the figures must be clearly readable and may not be written one on top of the other. The studies included have the common limitations of small sample size, broad age range, and wide discrepancy in total treatment time received. The limited relevant studies and data require future efforts in examining the approaches in more specific age groups, broader populations (e.g., more-verbal autistic children), and across different cultural contexts. The realization of further studies relies largely on standardized and detailed protocols of each treatment approach including the specification of materials used and regulations of procedures.

Moreover, efforts are called for the popularization of the approaches of music therapy. This necessitates a thorough analysis of the financial effects and procedural difficulties, as well as a careful evaluation of the requisite expertise in relevant domains. Specifically, for FCMT, it is necessary to consider if a set program of training and coursework could enable parents of autistic children to conduct this kind of therapy skillfully without the supervision of a licensed therapist. If such home-based treatments of low cost and high practicability is feasible, it would potentially benefit numerous children with ASD, as well as their families, especially in countries or regions with limited access to ASD professionals and relevant medical resources. Additionally, for AMMT and MBCT, the development of AI therapist programs should be prioritized to mitigate human resource costs and expedite the dissemination of these therapies.

5.Conclusions

The current review demonstrates that AMMT, FCMT and MBCT, as approaches to music therapy, are effective and beneficial to children with ASD in different aspects. Furthermore, it suggests the possibility of integration of the three approaches. AMMT has been demonstrated to enhance autistic children’s speech and response. FCMT has exhibited positive impacts on social interactions, parent-child relationships, and preverbal communicative actions, while MBCT has been found to be effective in eliciting speech and enhancing social language skills in nonverbal autistic children. The effectiveness of these therapies in various settings and languages needs to be further studied, and future efforts should focus on promoting the widespread adoption of these approaches, including assessing costs, addressing practical challenges, and developing AI therapist programs to facilitate their dissemination.