Earbuds with acoustic insert

1. An earbud comprising:

a housing having a non-occluding ear portion;

a directional sound port disposed in the non-occluding ear portion;

a driver assembly positioned within the housing and having a front volume disposed in front of the driver assembly and a back volume disposed behind the driver assembly;

an acoustic insert positioned within the housing behind the driver assembly and attached to an interior surface of the housing such that the acoustic insert and the housing together define (1) a multiport chamber and (2) a bass channel that is routed from the back volume to the multiport chamber;

a rear vent formed through the acoustic insert and coupling the back volume to the multiport chamber; and

a multiport vent formed through the housing and coupling the multiport chamber to an external environment.

2. The earbud of claim 1 wherein the acoustic insert includes a recess defined by raised weld regions that are bonded to the interior surface of the housing.

3. The earbud of claim 2 wherein the recess within the acoustic insert forms three walls of the bass channel and the housing forms a fourth wall of the bass channel.

4. The earbud of claim 1 wherein the acoustic insert is formed from a carbon doped plastic that absorbs laser energy.

5. The earbud of claim 1 wherein the earbud housing is made from Acrylonitrile butadiene styrene (ABS) with a titanium dioxide pigment.

6. The earbud of claim 1 wherein the acoustic insert is attached to an interior surface of the housing with a laser bonded interface.

7. The earbud of claim 1 wherein the acoustic insert is attached to an interior surface of the earbud housing with an adhesive.

8. The earbud of claim 1 wherein a length of the bass channel changes a frequency response of the earbud.

9. A method of forming an earbud, the method comprising:

forming a housing having an interior surface and an exterior surface;

forming an acoustic insert including a recess defined by raised weld regions;

positioning a driver assembly within the housing to form a front volume disposed in front of the driver assembly and a back volume disposed behind the driver assembly;

inserting the acoustic insert within the housing such that the raised weld regions are disposed against the interior surface of the housing;

directing a laser through the housing to impinge the raised weld regions of the acoustic insert and weld the raised weld regions to the interior surface of the housing such that the acoustic insert and the housing together define (1) a multiport chamber and (2) a bass channel that is routed from the back volume to the multiport chamber;

forming a rear vent through the acoustic insert to couple the back volume to the multiport chamber; and

forming a multiport vent through the housing to couple the multiport chamber to an external environment.

10. The method of forming an earbud of claim 9 wherein the housing is formed from a plastic that is substantially transparent to a wavelength of the laser.

11. The method of forming an earbud of claim 9 wherein the acoustic insert is formed from a carbon doped plastic that absorbs laser energy.

12. The method of forming an earbud of claim 9 wherein the acoustic insert forms three walls of the bass channel and the housing forms a fourth wall of the bass channel.

13. An earbud comprising:

a housing having an ear portion coupled to a stem;

a cavity formed within the ear portion;

a driver assembly positioned within the cavity and defining a front volume disposed in front of the driver assembly and a back volume disposed behind the driver assembly;

an acoustic insert positioned within the cavity behind the driver assembly and attached to an interior surface of the housing such that the acoustic insert and the housing together define (1) a multiport chamber and (2) a bass channel that is routed from the back volume to the multiport chamber;

a rear vent formed through the acoustic insert and coupling the back volume to the multiport chamber; and

a multiport vent formed through the housing and coupling the multiport chamber to an external environment.

14. The earbud of claim 13 wherein the acoustic insert includes a recess defined by raised weld regions that are bonded to the interior surface of the housing.

15. The earbud of claim 14 wherein the recess within the acoustic insert forms three walls of the bass channel and the housing forms a fourth wall of the bass channel.

16. The earbud of claim 13 wherein the acoustic insert is formed from a carbon doped plastic that absorbs laser energy.