Jet noise is the sound produced by momentum-driven flow through a nozzle or vent. Jet noise from a volcano has similar time and frequency characteristics to manufactured jet noise, although at lower frequencies. Volcanic jet noise is a new area of research and is notably more complex than discrete explosion infrasound. The manufactured jet noise community has established that jet noise varies as a function of the angle to the jet axis, which is parallel to the jet flow, and has derived empirical equations through extensive laboratory testing that relate jet noise to jet parameters, including flow rate, diameter, and temperature. However, these equations do not apply entirely to volcanoes, as volcanic jets are multiphase (comprising gas, ash, and tephra) and time-variable. Volcanologists are observationally limited to high jet axis angles as volcanic jets extend vertically into the atmosphere, and our instruments are deployed at the ground surface. I recorded fumarolic jet noise at Aso volcano at the smallest angle relative to vertical to date, using local topography, and characterized the signal (McKee et al., 2017). Using infrasound, thermal (to estimate jet temperature and diameter), and gas data (for volatile species concentrations), I estimated jet velocity and total volatile flux, providing the first such estimates using recorded volcanic jet noise, thermal data, and an assumed dimensionless number that describes oscillating flow.