Understanding Ultrasound and Aluminum Plate Interaction: Factors to Consider

[ChrisCOD]

Homework Statement

Hello. I have a question in relation to blocking ultrasound. Suppose we have a device which emits ultrasound. Lets suppose that is is focused ultrasound, and it emits it towards a target at a displaced location. The question is, if you place an aluminum plate between the target location and the device, supposing further that the surrounding medium of the aluminum plate is air, what will happen with respect to the ultrasounds ability to reach the target point?

Suppose you characterize the ultrasound in accordance with various parameters such as frequency, intensity, energy and potentially other parameters. How much of the original ultrasound energy would reach the target point considering the aluminum plate that sits between the device and the target point? Include in your answer consideration of reflection as well as absorption and any other mechanisms for the interaction with the ultrasound.

Relevant Equations

I am unsure of the relevant equations.

The solution involves understanding the interaction between the ultrasound and the aluminum plate. One factor to consider is the acoustic impedance mismatch which will cause reflection of a proportion of the ultrasound energy. There may be other factors to consider.

 

[Steve4Physics]

One factor to consider is the acoustic impedance mismatch which will cause reflection of a proportion of the ultrasound energy.

What are the values of acoustic impedance for the aluminium and the medium which surrounds it? (If you don't yet have values, first do your research and then tell us what you found.)