Cochlear implant manufacturers now offer
a multitude of speech processing strategies in their speech processors.
It is generally not known, however, which strategy will work the best for
a particular patient. So, clinicians now have the option to program the
patient with multiple strategies, and have the patient select the strategy
they prefer. In addition, clinicians have the capability, thanks to the
flexible fitting software, to change certain speech processing parameters
to optimize performance.
For patients fitted with the CIS strategy, clinicians can vary a number of parameters to optimize speech recognition performance for each patient. These parameters include pulse rate, pulse duration and stimulation order:
For patients fitted with the Nucleus’ CI24M device, clinicians have the option to select a subset of electrodes for stimulation. Research has shown that stimulating only a subset of electrodes, rather than all 22 electrodes, can produce significant benefits for some patients fitted with the CIS strategy. Plant et al. (1999) for instance, showed that some subjects preferred and performed better on word recognition with the CIS strategy when it was programmed with 8 channels than when it was programmed with 16 channels.
For patients fitted with the Clarion device, clinicians have the option to fit the patient with the CIS, the SAS or the PPS strategies. Research has shown that some patients prefer the SAS strategy to the CIS strategy (Osberger and Fisher, 1999; Battmer et al., 1999), while other patients prefer the PPS strategy to the CIS strategy (Armstrong-Bendall et al., 1999). In most cases, Clarion patients seem to perform better on speech recognition tasks with the strategy they prefer.
For patients fitted with the Med-El device (COMBI 40+), clinicians now have the option to fit patients with the n-of-m strategy, in addition to the CIS strategy. Research (Ziese et al., 2000) has shown that Med-El patients performed better with the 7-of-12 strategy (operating at a higher rate) than the CIS strategy (12 channels) on monosyllabic word recognition. This is consistent with research reported by Brill et al. (1997) showing that by trading channels with higher simulation rates (i.e., by using fewer number of channels to obtain higher rates of stimulation) performance can be improved.
Armstrong-Bendall, G., Goodrum-Clarke, K., Stollwerck, L., Nunn, T., Wei, J., Boyle P. (1999). “Clarion Paired Pulsatile Sampler (PPS): User Preference and Performance,” Conference on Implantable Auditory Prostheses, Pacific Grove, California.
Battmer, R., Zilberman, Y., Haake, P., Lenarz, T. (1999). “SAS-CIS Pilot Comparison Study in Europe,” Annals of Otology, Rhinology & Laryngology, 108, 69-73.
Brill, S., Gstottner, W., Helms, J., Ilberg, C.v., Baumgartner, W., Muller, J. and Kiefer, J. (1997). “Optimization of channel number and stimulation rate for the fast CIS strategy in the COMBI 40+,” American Journal of Otology, 18, S104-S106.
P. Loizou, O. Poroy and M. Dorman (2000). "The effect of parametric variations of cochlear implant processors on speech understanding," Journal of Acoustical Society of America, 108(2), 790-802.
Osberger, M. and Fisher, L. (1999). “SAS-CIS Preference Study in Postlingually Deafen Adults Implanted with the Clarion Cochlear Implant,” Annals of Otology, Rhinology & Laryngology, (Suppl. 177), 108(4), 74 – 79.
Plant, K., Whitford, L., Psarros, C., Vandali, A. and Clark, G. (1999). “Parameter selection and programming recommendations for the ACE and CIS speech processing strategies, 1999 Conference on Implantable Auditory Prosthesis, Pacific Grove, CA.
Wilson, B., Lawson, D. and Zerbi, M. (1993).
“Speech Processors for Auditory Prostheses,” NIH Project N01-DC-2-2401,
Fifth Quarterly Progress Report.
B. Wilson, D. Lawson, and M. Zerbi (1995). "Advances in coding strategies for cochlear implants," Advances in Otolaryngology - Head and Neck Surgery, 9, 105-129.
M. Ziese, A. Stutzel, H, von Specht, K.
Begall, B. Freigang, S. Sroka and P. Nopp (2000). “Speech understanding
with the CIS and n-of-m strategy in the MED-EL COMBI 40+ system,“ ORL,