An improved method to determine the onset timings of reflections in an acoustic impulse response.

Determining the absolute onset time of reflections in an acoustic impulse response (IR) has applications for both subjective and physical acoustics problems. Although computationally simple, a first-order energetic analysis of the IR can lead to false-positive identification of reflections. This letter reports on a method to determine reflection onset timings using a modified running local kurtosis analysis to identify regions in the IR where the distribution is non-normal.

Audio spectrum and sound pressure levels vary between pulse oximeters.

Purpose: The variable-pitch pulse oximeter is an important intraoperative patient monitor. Our ability to hear its auditory signal depends on its acoustical properties and our hearing. This study quantitatively describes the audio spectrum and sound pressure levels of the monitoring tones produced by five variable-pitch pulse oximeters.