Port placement for in-ear wearable with active noise cancellation

An in-ear wearable comprising:

• an electro-acoustic transducer;
• a housing supporting the electro-acoustic transducer such that the housing and the electro-acoustic transducer together define a first acoustic volume, the electro-acoustic transducer being arranged such that a first radiating surface of the electro-acoustic transducer radiates first acoustic energy into the first acoustic volume, wherein the housing and the electro-acoustic transducer together define a second acoustic volume, wherein a second radiating surface of the electro-acoustic transducer radiates second acoustic energy into the second acoustic volume, wherein the housing further defines an acoustic exit port positioned to direct the first acoustic energy into a user's ear when the housing is worn;
• a feedback microphone disposed within the first acoustic volume to receive the first acoustic energy, the feedback microphone including a microphone port and being configured to transduce acoustic energy received at the microphone port into a feedback microphone signal;
• and
• a port defined within the housing, the port extending from a first opening to a second opening, the first opening defining a boundary between the port and the first acoustic volume, wherein the port acoustically couples the acoustic volume to a space outside the housing such that outside acoustic energy from the space outside the housing enters the first acoustic volume through a path that does not pass through the second acoustic volume,
• wherein the first opening does not extend beyond a first plane tangent to a point of the microphone port nearest to the acoustic exit port and orthogonal to a longitudinal axis of the housing.