Final answer:
The claim about NICU-MT methodology research being limited to music therapy journals could be true or false and requires a comprehensive literature review across multiple databases to confirm.
Step-by-step explanation:
The statement that multiple types of NICU-MT methodology are documented in over 50 research articles found only in music therapy journals is a claim that can be true or false depending on the scope of publications one considers.
While it's plausible that many articles on NICU-MT (Neonatal Intensive Care Unit Music Therapy) are published in music therapy journals, it is important to conduct a comprehensive search to determine whether research on this topic exists outside of those specialized journals as well.
To validate the statement, one would need to conduct a thorough literature review across various databases, not limiting the search only to music therapy journals, as methodologies and studies may also be published in medical, psychological, and interdisciplinary journals.