Authentication method based at least on a comparison of user voice data

1. An authentication method comprising:

comparing user voice data received via an electronic device to a stored voice template to determine a voice authentication parameter;

determining a voice authentication threshold; and

comparing the voice authentication parameter to the voice authentication threshold to determine whether to authenticate the user;

wherein determining the voice authentication threshold comprises:

determining a current value of an enrolment counter indicating a number of times the stored voice template was modified since an initial enrolment process, or indicating a number of voice samples used to create the stored voice template;

comparing the current value of the enrolment counter to an enrolment counter threshold and determining whether the stored voice template is fully enrolled, indicating the stored voice template is complete or accurate, according to the result;

if the stored voice template is fully enrolled, setting the voice authentication threshold to a first voice authentication threshold; and

if the stored voice template is not fully enrolled:

comparing a device attribute received from the electronic device to a stored device attribute;

if the received device attribute matches the stored device attribute, setting the voice authentication threshold to a second voice authentication threshold determined by the current value of the enrolment counter; and

if the received device attribute does not match the stored device attribute, setting the voice authentication threshold to a third voice authentication threshold.

2. The method of claim 1 , wherein, in relation to the third voice authentication threshold, the second voice authentication threshold increases a range of voice authentication parameters which indicate authentication of the user.

3. The method of claim 1 , wherein the second voice authentication threshold is lower than the third voice authentication threshold; and

wherein authentication of the user is indicated if the voice authentication parameter is greater than the voice authentication threshold.

4. The method of claim 1 , wherein the third voice authentication threshold is equal to the first voice authentication threshold.

5. The method of claim 1 , further comprising modifying the stored voice template using the received user voice data if it is determined to authenticate the user.

6. The method of claim 5 , further comprising:

updating the enrolment counter if the stored voice template is modified.

7. The method of claim 6 , wherein the stored voice template is only modified if the stored voice template is not fully enrolled.

8. The method of claim 5 , wherein the stored voice template is only modified if the voice authentication parameter indicates a degree of similarity between the user voice data and the stored voice template within a predetermined range.

9. The method of claim 1 , further comprising performing an initial enrolment process, the initial enrolment process comprising:

receiving an initial user voice sample;

generating the stored voice template using the initial user voice sample;

receiving a device attribute of the electronic device associated with the user; and

storing the device attribute.

10. The method of claim 9 , wherein the initial enrolment process further comprises:

setting the enrolment counter to an initial value.

11. An authentication server comprising:

a receiver arranged to:

receive user voice data via an electronic device; and

receive a device attribute from the electronic device;

a memory arranged to store a stored voice template and a stored device attribute; and

a control unit arranged to:

compare the user voice data to the stored voice template to determine a voice authentication parameter;

determine a voice authentication threshold; and

compare the voice authentication parameter to the voice authentication threshold to determine whether to authenticate the user;

wherein, to determine the voice authentication threshold, the control unit is further arranged to:

determine a current value of an enrolment counter indicating a number of times the stored voice template was modified since an initial enrolment process or indicating a number of voice samples used to create the stored voice template;

compare the current value of the enrolment counter to an enrolment counter threshold and determine whether the stored voice template is fully enrolled, indicating the stored voice template is complete or accurate, according to the result;

if the stored voice template is fully enrolled, set the voice authentication threshold to a first voice authentication threshold; and

if the stored voice template is not fully enrolled:

compare a device attribute received from the electronic device to a stored device attribute;

if the received device attribute matches the stored device attribute, set the voice authentication threshold to a second voice authentication threshold determined by the current value of the enrolment counter; and

if the received device attribute does not match the stored device attribute, set the voice authentication threshold to a third authentication threshold.