Acoustic filters for microphone noise mitigation and transducer venting

An earpiece assembly for a playback device, the assembly comprising:

• an audio transducer;
• a housing containing the audio transducer, the housing defining an acoustic volume;
• an aperture in fluid communication with the acoustic volume;
• a first microphone and a second microphone;
• a support member disposed adjacent to the audio transducer, the support member comprising a first port substantially aligned with the first microphone, a second port disposed substantially aligned with the aperture, and a third port substantially aligned with the second microphone;
• and
• an acoustic filter material covering the first port and the second port, wherein the acoustic filter material has an acoustic impedance of about 30-150 RaylsMKS,
• wherein the first port and the second port have corresponding first and second areas, wherein the audio transducer has a downstream acoustic impedance based on the second area and an acoustic impedance of the acoustic filter material, and wherein the microphone has an upstream acoustic impedance based on the first area and the acoustic impedance of the acoustic filter material.

A portable playback device comprising:

• an audio transducer;
• an enclosure defining an acoustic volume adjacent the transducer;
• a vent opening in communication with the acoustic volume;
• a first microphone and a second microphone;
• a first port substantially aligned with the vent opening, the first port having a first area;
• a second port substantially aligned with the microphone, the second port having a second area;
• a third port substantially aligned with the microphone;
• and
• an acoustic impedance member extending over the first port, the second port, and the third port, wherein the acoustic impedance member has an acoustic impedance of about 30-150 RaylsMKS,
• wherein the audio transducer has a downstream acoustic impedance based on the first area and an acoustic impedance of the acoustic impedance member, and wherein the microphone has an upstream acoustic impedance based on the second area and the acoustic impedance of the acoustic impedance member.