1. Field of the Invention
The present invention relates to hearing prostheses and, more particularly, to user control of a hearing prosthesis.
2. Related Art
Hearing prostheses, such as cochlear implants (also referred to as cochlear prostheses, cochlear devices, and the like; for simplicity hereinafter referred to as “cochlear implant”) and hearing aids, are widely used to assist people with total or partial hearing loss. In general, modern devices of all types require the adjustment of operating parameters by skilled persons at the time of fitting.
For example, in the case of cochlear implants, after implantation there is a lengthy fitting process. The audiologist or clinician is required to create an initial map of electrodes, with various operating parameters for each electrode. The map is used to create the specific stimuli which are applied to the electrode, in accordance with the speech processing strategy employed by the particular implant system.
One of the more important operating parameters for each electrode is the dynamic range. This is generally set between two levels: the threshold or T level, which is the minimum stimulus which evokes a percept of sound, and the maximum comfortable or C level, which is the maximum stimulus which is not painful or damaging for the user (also referred to as the patient or recipient). It is desirable, for optimum perception of sound and speech by the user, that the dynamic range be correctly set. If it is too small, the range of amplitudes which can be perceived by the user is less than it could be, leading to a reduction in the range of different percepts which are possible and hence to reduced performance in speech perception. If the T level is too low, then stimuli are applied which cannot be perceived. If the C level is too high, then the patient may be overstimulated, leading to pain and possible injury to the patient.
It is known in some systems, for example in the Nucleus 4 system, to use a neural response based telemetry system to set a basic profile for each electrode. This is typically optimized by the clinician.
However, it is known that over time, and especially over the first few months of use, the dynamic range should be increased as the user becomes accustomed to the implant. Further, users may wish to have some control over the dynamic range of their implant.
Several approaches have been applied to address the issue of altering the dynamic range. For example, one approach is to use progressive maps, with increasing dynamic range, that are programmed into the speech processor. The patient may be encouraged, for example, to move to the next map each month. This needs to be done with great care, as the user may inadvertently choose the wrong map, and be overstimulated.
Another approach is to use the volume control of the map to allow the user to change the dynamic range. This approach also carries a risk that the user will select too large a dynamic range, and consequently be over-stimulated.
Another approach suggested has been to allow users to change their own profiles of T and C levels using shift and tilt controls. Again, this carries a risk that the user will select too large a dynamic range, and consequently be over-stimulated.
In the case of children, one of their parent(s) or caretaker(s) is/are generally the person/persons making such adjustments for the user. In many cases, they are cautious about altering settings, as they are concerned that the levels may become too loud for the child recipient. Consequently, they are often reluctant to use the existing systems to vary dynamic range. (In this and subsequent discussions, the term “user,” “recipient,” and “patient” is intended to encompass parent or caretaker in the case of children or other users having reduced capacity.
Although the foregoing is discussed mainly in the context of dynamic range, similar issues arise for other user adjustments. In some cases the incorrect adjustments may not potentially compromise safety, but they may produce sub-optimal treatment for the patient.