Method for determining a response function of a noise cancellation enabled audio device

1. A method for determining a response function of a noise cancellation enabled audio device, in particular headphones, the method comprising:

placing the audio device onto a measurement fixture, wherein a loudspeaker of the audio device faces an ear canal representation of the measurement fixture;

measuring a first response function between an ambient sound source and a test microphone located within the ear canal representation while parameters of a noise processor of the audio device are set to a proportional transfer function with a first gain factor;

measuring a second response function between the ambient sound source and the test microphone while parameters of the noise processor are set to a proportional transfer function with a second gain factor being different from the first gain factor;

determining a model response function for the noise processor based on the first response function, the second response function, the first gain factor, and the second gain factor.

2. The method according to claim 1 , further comprising;

determining an ambient-to-ear response function based on the first and/or the second response function; and

determining an overall processor response function based on the first response function, the second response function and the first and the second gain factor wherein

the model response function; is determined from the ambient-to-ear response function and the overall processor response function.

3. The method according to claim 1 , wherein the model response function F is determined according to the formula

F

=

a

⁢

⁢

1

-

X

⁡

(

a

⁢

⁢

2

-

a

⁢

⁢

1

)

Y

-

X

,

with a 1 being the first gain factor, a 2 being the second gain factor, X being the first response function and Y being the second response function.

4. The method according to claim 1 , wherein each of the response functions measured between the ambient sound source and the test microphone is measured without accessing any test point within the audio device.

5. The method according to claim 1 , wherein each of the response functions measured between the ambient sound source and the test microphone is measured without the audio device being disassembled during the respective measurements.

6. The method according to claim 1 , wherein the audio device and the noise processor are enabled for feedforward noise cancellation.

7. The method according to claim 1 , further comprising determining parameters of a filter function of the noise processor based on the model response function.

8. A method for determining a response function of a noise cancellation enabled audio device, in particular headphones, the method comprising:

placing the audio device onto a measurement fixture, wherein a loudspeaker of the audio device faces an ear canal representation of the measurement fixture;

measuring a first response function between an ambient sound source and a test microphone located within the ear canal representation while parameters of a noise processor of the audio device are set to a proportional transfer function with a first gain factor;

measuring a second response function between the ambient sound source and the test microphone while parameters of the noise processor are set to a proportional transfer function with a second gain factor being different from the first gain factor;

measuring a third response function between the ambient sound source and the test microphone while parameters of the noise processor are set to a proportional transfer function with a third gain factor being different from the first gain factor and the second gain factor;

determining a model response function for the noise processor based on the first response function, the second response function, the third response function, the first gain factor, the second gain factor, and the third gain factor.

9. The method according to claim 8 , further comprising;

determining an ambient-to-ear response function based on the first response function or on the first, the second and the third response function; and

determining an overall processor response function based on the first, the second and the third response function and on the first, the second and the third gain factor; wherein

the model response function is determined from the ambient-to-ear response function and the overall processor response function.

10. The method according to claim 8 , wherein the model response function F is determined according to the formula

F

=

a

⁢

⁢

1

-

X

⁡

(

a

⁢

⁢

3

-

a

⁢

⁢

2

)

Z

-

Y

,

with a 1 being the first gain factor, a 2 being the second gain factor, a 3 being the third gain factor, X being the first response function, Y being the second response function and Z being the third response function.

11. The method according to claim 9 , further comprising

determining a leakage response function based on the first, the second and the third response function and on the first, the second and the third gain; wherein

the overall processor response function is determined further based on the leakage response function.

12. The method according to claim 1 , wherein the first gain factor equals zero.

13. The method according to claim 12 , wherein the noise processor is disabled and/or muted during measurement of first response function.

14. A method for determining a response function of a noise cancellation enabled audio device, the method comprising:

placing the audio device onto a measurement fixture, wherein a loudspeaker of the audio device faces an ear canal representation of the measurement fixture;

measuring a first response function between an ambient sound source and a test microphone located within the ear canal representation while parameters of a noise processor of the audio device are set to a predefined transfer function in combination with a first gain factor;

measuring a second response function between the ambient sound source and the test microphone while parameters of the noise processor are set to the predefined transfer function in combination with a second gain factor being different from the first gain factor;

determining a model response function for the noise processor based on the predefined transfer function, the first response function, the second response function, the first gain factor, and the second gain factor.

15. The method according to claim 14 , further comprising;

measuring a third response function between the ambient sound source and the test microphone while parameters of the noise processor are set to the predefined transfer function in combination with a third gain factor being different from the first gain factor and the second gain factor; wherein

the model response function is determined based on the predefined transfer function, the first, the second and the third response function, and the first, the second and the third gain factor.

16. The method according to claim 15 , wherein each of the response functions measured between the ambient sound source and the test microphone is measured without accessing any test point within the audio device.

17. The method according to claim 15 , wherein each of the response functions measured between the ambient sound source and the test microphone is measured without the audio device being disassembled during the respective measurements.

18. The method according to according to claim 15 , wherein the audio device and the noise processor are enabled for feedforward noise cancellation.

19. The method according to according to claim 15 further comprising determining parameters of a filter function of the noise processor based on the model response function.

20. The method according to claim 14 , wherein the model response function F is determined according to the formula

F

=

a

⁢

⁢

1

-

X

⁡

(

a

⁢

⁢

2

-

a

⁢

⁢

1

)

Y

-

X

,

with a 1 being the first gain factor, a 2 being the second gain factor, X being the first response function and Y being the second response function.