Hearing aids and related devices and methods

1. A hearing aid comprising:

a microphone;

an electro-acoustic transducer; and

a housing supporting the electro-acoustic transducer such that the housing and the electro-acoustic transducer together define a first acoustic volume and a second acoustic volume, the electro-acoustic transducer being arranged such that a first radiating surface of the transducer radiates acoustic energy into the front acoustic volume and such that a second radiating surface of the transducer radiates acoustic energy into the second acoustic volume;

wherein the hearing aid is configured such that the first and second acoustic volumes are both acoustically coupled to the microphone when the hearing aid is worn, and

wherein the housing also supports an acoustic element that is acoustically coupled to the microphone and the second acoustic volume and arranged such that acoustic energy radiated from the acoustic element sums with acoustic energy leaked from the first acoustic volume at the microphone so as to cancel each other.

2. The hearing aid of claim 1 , wherein the acoustic element comprises a passive radiator or a membrane.

3. The hearing aid of claim 1 , wherein the acoustic element comprises a membrane formed integrally with the housing.

4. The hearing aid of claim 1 , wherein motion of the acoustic element is driven by operation of the electro-acoustic transducer.

5. The hearing aid of claim 1 , wherein the acoustic element comprises a piston that is mechanically coupled to the housing via a suspension, and wherein motion of the piston is driven by operation of the acoustic transducer.

6. The hearing aid of claim 1 , comprising a front port coupling the first acoustic volume to a space outside the housing; and

a rear port coupling the second acoustic volume to the space outside the housing.

7. The hearing aid of claim 6 , wherein the acoustic element is arranged acoustically in parallel with the rear port.

8. The hearing aid of claim 6 , wherein the acoustic element comprises a plurality of acoustic elements arranged acoustically in parallel with the rear port.

9. The hearing aid of claim 6 , wherein respective outlet ends of the rear port and the front port combine before exiting the housing via a combined exit volume and an exit port.

10. The hearing aid of claim 1 , wherein the housing defines a nozzle, and wherein the first acoustic volume is acoustically coupled to an acoustic passage in the nozzle such that the electro-acoustic transducer is acoustically coupled to a user's ear canal when the hearing aid is worn.

11. The hearing aid of claim 10 , further comprising an ear tip supported on the nozzle and configured to engage a user's ear canal when the hearing aid is worn.

12. The hearing aid of claim 11 , wherein the ear tip includes one or more apertures arranged such that the first acoustic volume is acoustically coupled to the microphone when the hearing aid is worn.

13. The hearing aid of claim 1 , further comprising:

a casing configured to sit behind a user's pinna when worn; and

wiring coupling the casing to the housing,

wherein the microphone is supported by the casing.

14. The hearing aid of claim 13 , further comprising: a battery, a microphone, and a sound processor housed in the casing.

15. The hearing aid of claim 1 , wherein the electro-acoustic transducer is a moving coil transducer.

16. The hearing aid of claim 1 , wherein the microphone is supported by the housing.

17. The hearing aid of claim 1 , wherein the microphone is arranged and configured to pick up ambient sound for amplification by the hearing aid.