What is the term for the percentage of ultrasound intensity that passes in the forward direction when a beam strikes an interface between two media?

What is the term for the percentage of ultrasound intensity that passes in the forward direction when a beam strikes an interface between two media?

• A. Intensity Absorption Coefficient
• B. Acoustic Impedance Ratio
• C. Intensity Transmission Coefficient
• D. Intensity Reflection Coefficient

Answer: (C)

When a sound wave hits the boundary between two media, part of the energy is reflected and part enters the second medium. The fraction that continues forward across the boundary is the intensity transmission coefficient. At normal incidence, this depends on the acoustic impedances Z1 and Z2 of the two media and can be expressed as T = 4Z1Z2/(Z1+Z2)^2, showing that equal impedances yield complete transmission while a larger mismatch increases reflection. The reflected portion is given by R = ((Z2−Z1)/(Z2+Z1))^2. Absorption in the second medium can reduce transmitted energy as the wave travels, but the transmission coefficient specifically quantifies the energy that passes through the boundary.

When a sound wave hits the boundary between two media, part of the energy is reflected and part enters the second medium. The fraction that continues forward across the boundary is the intensity transmission coefficient. At normal incidence, this depends on the acoustic impedances Z1 and Z2 of the two media and can be expressed as T = 4Z1Z2/(Z1+Z2)^2, showing that equal impedances yield complete transmission while a larger mismatch increases reflection. The reflected portion is given by R = ((Z2−Z1)/(Z2+Z1))^2. Absorption in the second medium can reduce transmitted energy as the wave travels, but the transmission coefficient specifically quantifies the energy that passes through the boundary.