Where R is the fraction of reflection, and z 1 and z 2 are the acoustic impedances of the two materials, analogous to refractive index in light propagation.
32.
It was found that a layer with high acoustic impedance with a backing of a softer, low acoustic impedance layer ( such as low density foam ) would protect from blast injury.
33.
It was found that a layer with high acoustic impedance with a backing of a softer, low acoustic impedance layer ( such as low density foam ) would protect from blast injury.
34.
This sound pulse is reflected back to a microphone and this reflection is generated according to the changes in the local acoustic impedance related to cross-sectional area of the nasal cavity.
35.
The windscreen, based on the high transmission coefficient of infrasound through matter, is made of a material having a low acoustic impedance and has a sufficiently thick wall to ensure structural stability.
36.
Critical variables affecting this acoustic impedance include : chimney length ( hole between lip-plate and head tube ), chimney diameter, and radiuses or curvature of the ends of the chimney.
37.
This is the intermediate situation, that occurs during sediment compaction with depth, between the acoustic impedance relationship required for a bright spot and the acoustic impedance relationship required for a dim spot.
38.
This is the intermediate situation, that occurs during sediment compaction with depth, between the acoustic impedance relationship required for a bright spot and the acoustic impedance relationship required for a dim spot.
39.
A hydrophone can " listen " to sound in air but will be less sensitive due to its design as having a good acoustic impedance match to water, which is a denser fluid than air.
40.
The sensitivity of these devices continues to improve; a newly developed piezoelectric transducer can produce frequencies in the MHz that can easily propagate through even high acoustic impedance materials such as steel and dense ceramics.
