Earphone port

A port tube for an earphone, wherein the port tube is configured to acoustically couple a rear acoustic cavity of the earphone to an external environment, the port tube comprising:

• a first, curved, section that is proximate the rear cavity and defines a first cross-sectional area;
• a second, transitional, section that is coupled to the first section and defines a gradually increasing cross-sectional area;
• a third, curved and banked, section that is coupled to the second section and defines a second cross-sectional area that is greater than the first cross-sectional area, and comprising an inner wall, an outer wall, and a lower wall that meets the inner wall and the outer wall, and wherein the banking comprises the inner wall having a length that is greater than a length of the outer wall;
• a fourth, transitional, section that is coupled to the third section and defines a gradually decreasing cross-sectional area;
• and
• a fifth, curved, section that is coupled to the fourth section and defines a third cross-sectional area that it less than the second cross-sectional area;
• wherein the second and fourth sections each transition approximately the same amount in cross-sectional area;
• wherein the tube has a length dimension along its length and a width dimension across its width that is orthogonal to its length, and wherein the width dimension is approximately the same along the entire length dimension;
• and
• wherein the first, third, and fifth sections each have a constant cross-sectional area along lengths thereof, wherein the cross-sectional areas of the first and fifth sections are the same, and the cross-sectional area of the third section is greater than that of the first and fifth sections.