Low‐frequency acoustic measurements at Los Alamos

1994 ◽  
Vol 96 (5) ◽  
pp. 3334-3334
Author(s):  
Rodney W. Whitaker
Keyword(s):  
Low Frequency ◽  
Acoustic Measurements ◽  
Los Alamos

scholarly journals Passive underwater acoustic evolution of a calving event

2012 ◽  
Vol 53 (60) ◽  
pp. 113-122 ◽  
Author(s):  
Erin C. Pettit
Keyword(s):  
Spectral Characteristics ◽  
Low Frequency ◽  
Acoustic Measurements ◽  
Dynamic Nature ◽  
High Frequencies ◽  
Direct Measurements ◽  
Audible Sound ◽  
Passive Acoustic ◽  
Remotely Sense ◽  
Ocean Boundary

AbstractDirect measurements of processes occurring at the ice–ocean boundary are difficult to acquire because of the dangerous and dynamic nature of the boundary, yet these processes are among the least well understood in glaciology. Because sound travels well through water, passive underwater acoustics offers a method to remotely sense activity at this boundary. Here we present passive acoustic measurements and spectral analysis of the evolution of a subaerial calving event and the subsequent mini-tsunami and seiche at Meares Glacier, Alaska, USA. Using two hydrophones to record sound from 1 to 40 000 Hz, we find that each phase of a calving event has distinctive spectral characteristics. An event begins with an infrasound rumble (1–20 Hz), then the ice fractures (20–100 Hz), falls and impacts the water (200–600 Hz). High-frequency (>10 000 Hz) sound increases in intensity quickly as the iceberg oscillates, creating turbulence, spray and waves. Within 10 s, the low-frequency audible sound dissipates and the mini-tsunami and seiche sounds dominate (infrasound plus high frequencies) and continue for over 10 min. The specific frequencies and duration of each phase of a calving event depend on its size and location and the glacier and fjord characteristics.

Determination of cancellous bone density using low frequency acoustic measurements

2008 ◽  
Vol 87 (10-11) ◽  
pp. 1213-1225 ◽  
Author(s):  
Robert P. Gilbert ◽  
Philippe Guyenne ◽  
George C. Hsiao
Keyword(s):  
Bone Density ◽  
Cancellous Bone ◽  
Low Frequency ◽  
Acoustic Measurements

scholarly journals Handclap for Acoustic Measurements: Optimal Application and Limitations

Acoustics ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 224-245 ◽  
Author(s):  
Nikolaos M. Papadakis ◽  
Georgios E. Stavroulakis
Keyword(s):  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Acoustic Parameter ◽  
Reverberation Time ◽  
Octave Band ◽  
Acoustic Measurements ◽  
Frequency Range ◽  
Acoustic Source ◽  
Signal To Noise ◽  
Acoustic Parameters

Handclap is a convenient and useful acoustic source. This study aimed to explore its optimal application and limitations for acoustic measurements as well for other possible utilizations. For this purpose, the following steps were performed: investigation of the optimal hand configuration for acoustic measurements and measurements at different microphone source distances and at different spaces and positions. All measurements were performed with a handclap and a dodecahedron speaker for comparison. The results indicate that the optimal hand configuration (among 11) is with the hands cupped and held at an angle due to the superior low frequency spectrum. This configuration produced usable acoustic parameter measurements in the low frequency range in common room background levels unlike other configurations. The reverberation time was measured across different spaces and positions with a deviation less than three and just a noticeable difference of the signal-to-noise ratio within or near the ISO 3382-1 limits for each corresponding octave band. Other acoustic parameters (i.e., early decay time, clarity) were measured with greater deviations for reasons discussed in the text. Finally, practical steps for measurements with a handclap as an acoustic source are suggested.

scholarly journals Acoustic Comfort Investigation in Residential Timber Buildings in Sweden

2019 ◽  
Vol 24 (1) ◽  
pp. 78-89 ◽  
Author(s):  
Delphine Bard ◽  
Nikolas GEORGIOS Vardaxis ◽  
Elin Sondergard
Keyword(s):  
Questionnaire Survey ◽  
Low Frequency ◽  
Frequency Noise ◽  
Light Weight ◽  
Acoustic Measurements ◽  
Noise Sources ◽  
Impact Noise ◽  
Swedish Family ◽  
Combining Data ◽  
Acoustic Comfort

This article presents parts of a wide survey on acoustic comfort in Swedish family buildings, specificallywith focus on timber light-weight buildings. The scope of the whole research is to investigate acousticcomfort dimensions after collecting and combining data from standardized acoustic measurements andsubjective responses from a questionnaire survey. Certain noise sources were reported as dominantwithin living environments, impact noise from neighbors being the most important. Installation noisefrom inside the building and outdoor low-frequency noise disturb also a lot. However, the overall levelof acoustic comfort in contemporary wooden buildings seems satisfactory.

Sound speed and attenuation in muddy sediments from low-frequency acoustic measurements

2017 ◽  
Vol 142 (4) ◽  
pp. 2556-2556
Author(s):  
Lin Wan ◽  
Mohsen Badiey ◽  
D. P. Knobles ◽  
Preston S. Wilson ◽  
Justin Eickmeier
Keyword(s):  
Sound Speed ◽  
Low Frequency ◽  
Acoustic Measurements ◽  
Muddy Sediments
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