Open audio device

An open audio device, comprising:

• a housing;
• an acoustic radiator in the housing that emits front-side acoustic radiation from its front side and emits rear-side acoustic radiation from its rear side;
• a front acoustic cavity located at least in part in the housing that receives front-side acoustic radiation and defines a first front sound-emitting opening that is configured to be located anteriorly of a user's ear canal opening;
• a rear acoustic cavity located at least in part in the housing that receives rear-side acoustic radiation and defines at least a first rear sound-emitting opening and a separate second rear sound-emitting opening that is spaced from the first rear sound-emitting opening;
• and
• an elongated spout piece that is configured to be removably coupled to the housing such that it covers the first front sound-emitting opening and thereby lowers a resonance frequency of the front acoustic cavity, wherein the spout piece is configured to conduct sound from the first front sound-emitting opening to spout piece sound-emitting opening that is closer to the ear canal opening than is the first front sound-emitting opening, but is not in the ear canal opening, and wherein the spout piece is further configured to cover the second rear sound-emitting opening but not the first rear sound-emitting opening, and thereby lower a resonance frequency of the rear acoustic cavity.