Assessing the validity of the ray model using sound reflection

Abstract In this paper, we present a straightforward experiment using sound reflection to evaluate the validity of ray acoustic models. The ratio of the wavelength of sound waves to the focal length of the reflector ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi>d</mml:mi> </mml:mrow> </mml:math> ) is varied. For very small ratios, the wave nature is not manifested and the ray model can perfectly explain the outcomes. As this ratio increases, the ray model can only predict some aspects of the results. When <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi>d</mml:mi> </mml:mrow> </mml:math> reaches 0.4, the interference effects become dominant and consequently the ray model completely fails to explain the measurements.