The aim of the proposed experiment is to explore phonon dynamics in boron arsenide (BAs) and to infer the lattice contribution to the thermodynamical properties necessary for the understanding of a recently predicted anomalous ultrahigh thermal conductivity in this material. The estimated thermal conductivity of BAs at room temperature was found to be close to that of diamond or even exceeding it. The prohibitive cost together with its slow growth rate limit the use of diamond in practice. Therefore the understanding of phonon-driven mechanisms leading to the enhancement of thermal conductivity in BAs, beyond the isotopic effect, would help to better identify similar simple structure materials which would serve for high power applications requiring efficient passive cooling devices.