Acoustic band-pass filter assemblies, wireless blockage monitors, and related methods

A wireless blockage monitor for determining a rate of flow, the wireless blockage monitor comprising:

• a sensor membrane configured to be impacted by a flowing material;
• a microphone configured to receive acoustic energy created by impact of the sensor membrane;
• a tube connecting the sensor membrane to the microphone;
• and
• a band-pass filter disposed between the tube and the microphone, wherein the band-pass filter comprises:
• an inlet connected to the tube;
• and
• a plurality of resonator chambers disposed in series between the inlet and the microphone and configured to transmit acoustic energy between the inlet and microphone, plurality of resonator chambers including:
• at least one open resonator chamber, wherein the first end includes a first wall with an opening therethrough and wherein the second end is fully open;
• and
• a closed resonator chamber disposed adjacent the microphone, wherein the first end has a second wall with an opening therethrough connecting the closed resonator chamber to the second end of the at least one open resonator chamber, wherein the second end of the closed resonator chamber has a closed wall, and wherein the microphone forms at least a portion of the closed wall;
• wherein the cross-section of each resonator chamber increases between the inlet and the microphone.

A method of forming an acoustic band-pass filter assembly, the method comprising:

• forming a body defining an inlet, an open end, and a plurality of resonator chambers disposed in series between the inlet and the open end, each of the plurality of resonator chambers having a different cross-sectional area;
• wherein the cross-section of each resonator chamber increases between the inlet and the open end;
• providing an end wall over the open end of the body, the end wall configured to receive a microphone;
• and
• providing a microphone on the end wall.