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This study evaluates end-correction behavior in flue organ pipes by comparing two models: the classical low-frequency expression of Levine and Schwinger and the empirical, frequency-dependent refinement of Davies et al. [Journal of Sound Vibration 72 (1980) 543–546], later revisited by Moore et al. [JASA Express Letters 3 (2023) 055002]. Using a Microflown probe, we performed high-resolution pressure measurements inside and outside circular and square pipes to capture the transition from standing-wave to radiating behavior. Sinusoidal variation within the end-correction region and 1/rdecay beyond were observed, consistent with theory. A two-region curve-fitting approach quantified each model’s accuracy. In the tested range (0.049 ≤ ka ≤ 0.377), both models reproduced the data with nearly identical accuracy (R² ≥ 0.997), with only a slight advantage for the classical form in one square-pipe case. Probe interference was evaluated and found negligible. While the analysis employs fixed end-correction values rather than a universal fit, it provides a controlled test of how well existing models capture the spatial pressure field near the pipe termination. Results indicate that both models are adequate in this regime, and that the radiating field beyondδfollows a robust 1/rdecay independent of model choice. 

Accurate measurement of note-to-note transitions is essential for analyzing articulation in clarinet performance. Traditional methods rely on either subjective amplitude thresholds—such as the time between 5% and 95% RMS levels—or direct measurement of tongue-reed contact time using reed-mounted sensors. These approaches are limited by their dependence on user-defined parameters or invasive hardware. This study proposes a computational alternative: ΔT, a curvature-based metric defined as the time interval between surrounding minima in the second derivative of the mouthpiece pressure envelope. Using data from a sensor-equipped mouthpiece (SEM), we compare ΔT to both threshold-based timing (Tt) and tongue contact duration (Tc) across portato and staccato articulations. Our findings show that ΔT closely tracks both Tt and Tc in structured articulations, with minimal absolute difference and robust repeatability. These results support the use of ΔT as a non-invasive, objective, and reliable estimate of transition duration, enabling broader application in performance analysis, pedagogy, and real-time feedback systems. This research was funded by: National Science Foundation Grant 2109932. 

As the frequency of rocket launches increases, accurately predicting their noise is necessary to assess structural, environmental, and societal impacts. NASA’s Space Launch System (SLS) is a challenging vehicle to model because it has both solid-fuel rocket boosters and liquid-fueled engines that contribute to its thrust at launch. This paper discusses measured aeroacoustic properties of this super heavy-lift rocket in the context of supersonic jet theory and measurements of other rockets. Using four measured aeroacoustic properties: directivity, spectral peak frequency, maximum overall sound pressure level, and overall sound power level, an equivalent rocket based on merged plumes is created for SLS. With the constraint that the effective thrust and mass flow rates should match those of the actual vehicle, a method using weighted averages of the disparate plume parameters successfully reproduces SLS’s desired aeroacoustic properties, yielding a relatively simple model for the complex vehicle. 

Correctly predicting the playing frequencies of a musical instrument is dependent on the length of the resonator with the addition of an end correction. There are multiple theories describing this end correction, perhaps the simplest being that the end correction of a pipe is a physical extension of the sinusoidal pressure standing wave inside the pipe. However, recent optical imaging of the flow in a flue organ pipe found an unexpected exponential decay of pressure just outside of the pipe. This work looks to validate those findings acoustically. A flue organ pipe was played at the 1st, 5th, and 7th harmonics and the pressure just inside and immediately outside the end of the pipe played was measured using a zero-degree PU Match Microflown sound intensity probe. These measurements were fit to both exponential and sinusoidal curves and compared to the optical images. While an exponential trend is in fact apparent in some cases, the goodness-of-fit appears to be dependent on which harmonic is sounding. Future work includes exploration of a potential transitional region, assessing the impact of altered pipe geometry (both cross-sectional shape and size), and investigating potential sensor interference by using other measurement equipment. 

Not AvailableThis paper investigates the measured far-field noise from the Space Launch System’s Artemis-I mission liftoff. Pressure waveform data were collected at seven locations 12 to 50 kilometers from Kennedy Space Center’s (KSC) Launch Complex 39B in Cape Canaveral, Florida. Reported are initial analyses of these measurements outside the perimeter of KSC, including waveform characteristics, overall sound pressure levels, and frequency spectra. Analyses build upon an initial publication [K. L. Gee et al., JASA Exp. Lett. 3, 023601 (2023)] that documented acoustical phenomena at stations 1.5 to 5.2 km from the pad and contributed to a more complete understanding of the noise produced by super heavy-lift launch vehicles. At the stations discussed in this paper, maximum overall sound pressure levels ranged from less than 65 dB to 116 dB with significant variations seen at equidistant locations. As distance increases, one-third-octave band spectra show a significant decrease in peak frequency from 18 Hz down to 3 Hz and a reduction in relative high-frequency content.