Testing apparatus for detecting obstructions in multi-layer cellular structures and associated system and method

A system for detecting obstructions in a multi-layer cellular structure, the system comprising:

• a multi-layer cellular structure comprising a testing surface that is acoustically permeable;
• a testing apparatus configured to be positioned on the testing surface of the multi-layer cellular structure, the testing apparatus comprising:
• a tube comprising a first end, a second end, and a tube length extending between the first end and the second end, wherein the tube defines an internal passage with a first cross-sectional dimension;
• a loudspeaker mounted in the internal passage proximate the first end of the tube, wherein the loudspeaker has a sound-emitting portion facing toward the second end of the tube and a non-emitting portion facing away from the second end of the tube;
• a cap at to the second end of the tube, wherein the cap comprises an opening with a second cross-sectional dimension and the second cross-sectional dimension of the opening is smaller than the first cross-sectional dimension of the internal passage;
• and
• audio signal connectors operably connected to the loudspeaker and extending from the tube, the audio signal connectors configured to transmit a input signal to the loudspeaker and transmit a speaker output signal from the loudspeaker;
• and
• an external audio interface operably coupled to the testing apparatus and configured to generate the input signal and receive the speaker output signal.

A method for detecting obstructions in a multi-layer cellular structure, the method comprising:

• positioning a testing apparatus at an initial testing location that is acoustically permeable on a testing surface of the multi-layer cellular structure, the testing apparatus comprising a loudspeaker enclosed within a tube and configured to emit sound waves toward the multi-layer cellular structure through an opening;
• transmitting an input signal from an external audio interface to the loudspeaker via audio signal connectors;
• emitting sound waves from the loudspeaker through the opening of the testing apparatus toward the multi-layer cellular structure;
• receiving a speaker output signal from the loudspeaker via the audio signal connectors, the speaker output signal providing voltage and current data associated with an interaction of the emitted sound waves with the multi-layer cellular structure;
• and
• determining an electrical impedance of the loudspeaker based on voltage and current data corresponding to the loudspeaker, wherein the electrical impedance represents acoustic absorption characteristics of the multi-layer cellular structure at the initial testing location.