From education to manufacturing and medicine, the Microsoft HoloLens 2 mixed reality headset has been increasingly adopted. Text entry is a core functionality of the HoloLens 2, enabling communication and search features. The device tracks hand and finger movements interacting with a virtual keyboard but is slow and cumbersome. Speech-to-text dictation is a promising alternative requiring less physical effort and time. However, the HoloLens 2 dictation performance in environmental settings with varying noise levels is unclear. This study investigated the text input accuracy (WER), speed (WPM), and user perceptions of the HoloLens 2 dictation across three background noise levels (40 dB, 55 dB, and 70 dB). The 70 dB condition resulted in inferior outcomes for text input speed, perceived usability, mental demand, temporal demand, and effort. Users also reported lengthy processing delays in the 70 dB condition, while accuracy remained consistent (2–5% WER) across all noise conditions.