Alvarsson, Wiens, and Nilsson (2010) measured physiological stress markers in 40 subjects after stress induction. Nature sounds (including flowing water) facilitated faster sympathetic nervous system recovery compared to traffic noise conditions. The nature sound condition showed the shortest half-life for skin conductance recovery.
Galbrun and Ali (2013) found that water sounds function as informational maskers, redirecting cognitive attention rather than simply overpowering competing sounds. This means flowing water doesn't just block distracting noise, it actively redirects the brain's attention processing.
The "musical" quality of stream sounds comes from Minnaert resonance: air bubbles trapped in turbulent flow oscillate at specific frequencies based on their size, creating a naturally varied, non-repeating texture that prevents auditory habituation.