Cochlear implant

• US 6,778,858 B1
• Filed: 04/18/2002
• Issued: 08/17/2004
• Est. Priority Date: 09/16/1999
• Status: Expired due to Term

• Current Assignee: Advanced Bionics AG (Sonova Holding AG)
• Original Assignee: Advanced Bionics NV (Sonova Holding AG)
• Inventors: Peeters, Stefaan
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US10/088,194
• Time in Patent Office: 852 Days
• Field of Search: 607/55, 607/56, 607/57, 607/137, 600/25
• US Class Current: 607/57
• CPC Class Codes: A61N 1/0541 Cochlear electrodes
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: H03H 17/02 Frequency selective networks digital computers for complex mathematical operations G06F17/10

Abstract

A cochlear implant comprising a storage buffer in which sampling values derived from a sound signal are saved. The storage buffer is connected to a multichannel waveform generator, in which data for a stimulation strategy are saved. Reading and writing to the peak hold buffer occurs asynchronously.

Claims

1. A cochlear implant comprising a signal processor having a set of audio channel units and being provided for the conversion of sound signals, according to a frequency related tonotopic division, each audio channel being provided for applying a frequency related filtering to said sound signal, each audio channel having an output associated with a first sampling unit provided for sampling at an audio channel associated sampling rate the signal output by its associated audio channel unit and writing sampled signal values into a storage buffer, each sampling unit being connected with said storage buffer provided for temporarily storing said sampled signal values, said storage buffer being connected with a waveform generator comprising at least one stimulation channel, said waveform generator and said storage buffer being connected to a read signal generator provided for generating read signals enabling to read the stored sampled signal values from said storage buffer, said waveform generator being provided for retrieving under control of said read signal said sampled signal values of each audio channel from said storage buffer and for generating based on said sampled signal values waveforms having a time period and a wave pattern, said waveform generator being provided for stimulating by means of said waveforms electrode contacts of said cochlear implant, characterised in that said read signal generator is provided for generating said read signals asynchronously from said writing into said storage buffer.

2. A cochlear implant as claimed in claim 1, characterised in that said storage buffer is provided to set a stored sampled signal value to a preset value under control of a read signal after read of the stored value, each audio channel unit and said storage buffer are connected to a comparator, said comparator being provided for comparing a sampled signal value supplied by an audio channel with the stored sampled signal value for that audio channel and for generating a writing signal if said supplied sampled signal value has a higher absolute signal value than said stored sampled absolute signal value, said storage buffer being provided for storing said supplied sampled signal value under control of said writing signal.

3. A cochlear implant comprising M (M>

1) electrode contacts and a signal processor having a set of N audio channel units and being provided for the conversion, according to a frequency related tonotopic division, of sound signals, each audio channel being provided for applying a frequency related filtering to said sound signal, each audio channel having an output associated with a second sampling unit provided for sampling at a audio channel associated sampling rate the signal output by its associated audio channel unit and writing them into a storage buffer, each second sampling unit being connected with said storage buffer provided for temporarily storing sampled signal values supplied by its associated second sampling unit, characterised in that said storage buffer is connected with a stimulation channel configuration unit provided for defining stimulation channels in order to create electrical fields along auditory neural structures, said stimulation channel configuration unit being further provided to allocate to each stimulation channel at least two of said electrode contacts, to each stimulation channel there being assigned a memory element provided for storing a waveform pattern and a wave duration according to and during which an intensity value determined on the basis of the sampled signal value attributed to the considered stimulation channel is applicable to the electrodes assigned to the considered stimulation channel, said memory element being further provided for storing a maximum value for said intensity value indicating a maximum field strength for the considered stimulation channel and a first and second field identifier identifying a field spread in a basal and apical direction relative to a position of the electrode contacts of the considered stimulation channel.

4. A cochlear implant according to claim 3, characterised in that it comprises a stimulation sequence identifier provided for identifying a set of groups of stimulation channels which are simultaneously stimulatable, the stimulation channels of a same group being selected in order to enable a neural stimulation at neural excitation locations which match with neural excitation locations that would be obtained if the individual stimulation channels of the group would have been stimulated sequentially in time, said stimulation sequence identifier being further provided for cyclically stimulating said groups of stimulating channels.

5. A cochlear implant according to claim 4, characterised in that said set of groups comprises all stimulation channels, each group of to said set comprises all stimulation channels that satisfy said match.

6. A cochlear implant as claimed in claim 4 or 5, characterised in that it comprises an ordering unit provided to order the groups within the set according to sequence defining the order according to which the different groups are sequentially stimulated.

7. A cochlear implant according to claim 6, wherein a time frame is assigned to each group of said set in such a manner that the time frame of the assigned group is at least equal to the waveform duration of the stimulation channel within the considered group having the largest waveform duration.

8. A cochlear implant according to claim 6, wherein said memory element is further provided for storing a neural-repair function H(t), with H(t)=1 for t<

T_AR where T_AR is the total refractery period and $H<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(t\right)=e-\left(\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t-T_{\mathrm{AR}}}{\mathrm{\tau <br><br>}}\right)$

where Δ

t is the stimulus interval and τ

a stimulation channel time constant.

9. A cochlear implant according to claim 5, wherein a time frame is assigned to each group of said set in such a manner that the time frame of the assigned group is at least equal to the waveform duration of the stimulation channel within the considered group having the largest waveform duration.

10. A cochlear implant according to claim 5, wherein said memory element is further provided for storing a neural-repair function H(t), with H(t)=1 for t<

T_AR where T_AR is the total refractery period and $H<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(t\right)=e-\left(\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t-T_{\mathrm{AR}}}{\mathrm{\tau <br><br>}}\right)$

where Δ

t is the stimulus interval and τ

a stimulation channel time constant.

11. A cochlear implant according to claim 4, wherein a time frame is assigned to each group of said set in such a manner that the time frame of the assigned group is at least equal to the waveform duration of the stimulation channel within the considered group having the largest waveform duration.

12. A cochlear implant according to claim 11, wherein said memory element is further provided for storing a neural-repair function H(t), with H(t)=1 for t <

T_AR where T_AR is the total refractery period and $H<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(t\right)=e-\left(\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t-T_{\mathrm{AR}}}{\mathrm{\tau <br><br>}}\right)$

where Δ

t is the stimulus interval and τ

a stimulation channel time constant.

13. A cochlear implant according to claim 4, wherein said memory element is further provided for storing a neural-repair function H(t), with H(t)=1 for t<

T_AR where T_AR is the total refractery period and $H<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(t\right)=e-\left(\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t-T_{\mathrm{AR}}}{\mathrm{\tau <br><br>}}\right)$

where Δ

t is the stimulus interval and τ

a stimulation channel time constant.

14. A cochlear implant comprising M (M>

1) electrode contacts and a signal processor having an input for receiving sound signals, said signal processor having a set of N audio channel units which are provided for applying a conversion of said sound signals according to a frequency related tonotopic division and wherein each audio channel unit is further provided for forming audio signal values by applying a frequency related filtering on said converted sound signals, said signal processor further comprising a sampling unit provided for generating for each audio channel unit an audio channel unit dependent sampling frequency (fsi), each audio channel unit having an output connected to a data input of a storage buffer which is provided for receiving said audio signal values sampled at said audio channel unit dependent sampling frequency and for temporarily storing said sampled audio signal values, wherein said signal processor comprises a stimulation channel configuration unit connected with said storage buffer and provided for configurating stimulation channels to create electrical fields along auditory neural structures, said stimulation channel configuration unit being connected to said electrode contacts and further provided to allocate to each stimulation channel at least two of said electrode contacts, to each stimulation channel there being assigned a memory element provided for storing a waveform pattern and a wave duration according to and during which an intensity value determined on the basis of the sampled signal value attributed to the considered stimulation channel is applicable to the electrode contacts allocated to the considered stimulation channel, said memory element being further provided for storing a maximum value for said intensity value indicating a maximum field strength for the considered stimulation channel and a first and second field identifier identifying a field spread in a basal and apical direction relative to a position of the stimulation channel.

15. The cochlear implant according to claim 14, further comprising a stimulation sequence identifier provided for identifying a set of groups of stimulation channels which are simultaneously stimulatable, the stimulation channels of a same group being selected to enable a neural stimulation at neural excitation locations which match with neural excitation locations that would be obtained if the individual stimulation channels of the group would have been stimulated sequentially in time, said stimulation sequence identifier being further provided for cyclically stimulating said groups of stimulating channels.

16. The cochlear implant according to claim 15, wherein said set of groups comprises all stimulation channels, each group of said set comprises all stimulation channels that satisfy said match.

17. The cochlear implant as claimed in claim 15, further comprising an ordering unit provided to order the groups within the set according to sequence defining the order according to which the different groups are sequentially stimulated.

18. The cochlear implant according to claim 15, wherein a time frame is assigned to each group of said set in such a manner that the time frame of the assigned group is at least equal to the waveform duration of the stimulation channel within the considered group having the largest waveform duration.

19. The cochlear implant according to claim 15, wherein said memory element is further provided for storing a neural-repair function H(t), with H(t)=1 for t<

T_AR where T_AR is the total refractery period and $H<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(t\right)=e-\left(\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t-T_{\mathrm{AR}}}{\mathrm{\tau <br><br>}}\right)$

where Δ

t is the stimulus interval and τ

a stimulation channel time constant.

20. The cochlear implant as claimed in claim 14, wherein said storage buffer is connected to a waveform generator which is provided for forming at least one stimulation channel, said waveform generator and said storage buffer being connected to a read signal generator provided for generating read signals enabling to read the stored sampled audio signal values from said storage buffer, said waveform generator being provided for retrieving under control of said read signal said sampled audio signal values of each audio channel unit from said storage buffer and for generating, based on said sampled audio signal values, waveforms having a time period and a wave pattern, said waveform generator being connected to electrode contacts of said cochlear implant and provided for stimulating by means of said waveforms said stimulation channels, wherein said read signal generator is provided for generating read signals asynchronously from said storing into said storage buffer.

21. The cochlear implant as claimed in claim 14, wherein said storage buffer is provided to set a stored sampled signal value to a preset value under control of a read signal after read of the stored audio signal value, each audio channel unit and said storage buffer are connected to a comparator, said comparator being provided for comparing a sampled audio signal value supplied by an audio channel unit with the stored sampled signal value for that audio channel unit and for generating a writing signal if said supplied sampled audio signal value has a higher absolute signal value than said stored sampled absolute audio signal value, said storage buffer being provided for storing said supplied sampled signal value under control of said writing signal.