An authentication method. The method comprises comparing user voice data received via an electronic device to a stored voice template to determine a voice authentication parameter. A voice authentication threshold is determined and the voice authentication parameter is compared to the voice authentication threshold to determine whether to authenticate the user. Determining the voice authentication threshold comprises determining a current value of an enrollment counter, then comparing the current value of the enrollment counter to an enrollment counter threshold and determining whether the stored voice template is fully enrolled according to the result. If the stored voice template is fully enrolled, the voice authentication threshold is set to a first voice authentication threshold. If the stored voice template is not fully enrolled then a device attribute received from the electronic device is compared to a stored device attribute. If the received device attribute matches the stored device attribute, the voice authentication threshold is set to a second voice authentication threshold determined by the current value of the enrollment counter. If the received device attribute does not match the stored device attribute, the voice authentication threshold is set to a third voice authentication threshold.