Low Frequency Acoustic Detection Research in Support of Human Detection Range Prediction

摘要

This project resulted in modifications to the acoustic range prediction software that were intended to increase the accuracy with which the program predicts detection ranges for targets that are audible primarily at low frequencies. These modifications were based on interpretations of the findings of a psychoacoustic experiment that sought to determine the effective masking bandwidth for human observers at frequencies as low as 40 Hz. The rationale for this experimentation was based on an extensive search of the masking literature. The possibility that acoustic detection ranges of unaided human observers are affected by infrasonic emissions of helicopters was considered both analytically and empirically. It was concluded from a literature review that the prospects for 'infrasonic cueing' of conventional acoustic detection were doubtful. A two-alternative forced choice task in which infrasound was available as a cue to detection produced results consistent with that conclusion.