Feedforward ANR device acoustics

An ANR device comprising a first earpiece, the first earpiece comprising:

• a first casing defining a first front cavity having an opening;
• a first ear coupling disposed about the opening of the first front cavity and having a first passage formed through the first ear coupling, the first ear coupling being structured to engage a first portion of the head of a user of the ANR device to acoustically couple the first front cavity through the opening and the first passage to an ear canal of a first ear of the user, and the first ear coupling being structured to engage the first portion of the head of the user to form at least a partial seal between the first ear coupling and the first portion of the head of the user to provide passive noise reduction that limits entry of noise sounds emanating from an environment external to the first casing into at least the ear canal of the first ear;
• a first acoustic driver disposed within the first casing to acoustically output sounds into the first front cavity to be conveyed through the opening of the first front cavity and the first passage to the ear canal of the first ear;
• a first feedback microphone disposed within the first front cavity to detect noise sounds present within at least the first front cavity to enable the provision of feedback-based ANR;
• a first feedforward microphone carried by the first casing and acoustically coupled to the environment external to the first casing to enable the provision of feedforward-based ANR;
• and a first leak aperture formed in the first casing to couple the first front cavity to the environment external to the first casing, wherein the first casing further defines another cavity having a cavity opening coupling the another cavity to the environment external to the casing;
• the earpiece further comprises a cavity cover structured to close the cavity opening with a leaky closure by which the another cavity remains at least acoustically coupled to the environment external to the casing;
• and the first leak aperture couples the first front cavity to the environment external to the casing indirectly through the another cavity and through the leaky closure by which the cavity cover closes the cavity opening, the passive noise reduction provided by engagement of the first ear coupling to the portion of the head of the user is effective against higher audible frequency noise sounds emanating from the environment external to the first casing;
• the provision of the feedforward-based ANR enabled by the first feedforward microphone is effective against midrange audible frequency noise sounds emanating from the environment external to the first casing;
• and the provision of the feedback-based ANR enabled by the first feedback microphone is effective against lower audible frequency noise sounds emanating from the environment external to the first casing.