title: Intensity coding in electric hearing: effects of electrode configurations and stimulation waveforms.
abstract: OBJECTIVE
  Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem.
  
  
  METHODS
  The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were five Clarion cochlear implant users. For each subject, data from apical, middle, and basal electrode positions were collected when possible.
  
  
  RESULTS
  Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels.
  
  
  CONCLUSIONS
  The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen.
authors: Department of Biomedical Engineering, University of California, Irvine, California 92697, USA.
authors: Tiffany Elise H
authors: TE
authors: Chua
authors: Mark
authors: M
authors: Bachman
authors: Fan-Gang
authors: FG
authors: Zeng
references: Otol Neurotol. 2005 Sep;26(5):957-64
references: 16151343
references: Hear Res. 1999 Apr;130(1-2):171-88
references: 10320107
references: J Acoust Soc Am. 2000 Aug;108(2):760-3
references: 10955643
references: J Acoust Soc Am. 1980 Mar;67(3):868-74
references: 6892642
references: J Acoust Soc Am. 1982 Aug;72(2):406-10
references: 7119282
references: Hear Res. 2003 Jan;175(1-2):200-14
references: 12527139
references: Acta Otolaryngol. 2004 May;124(4):371-5
references: 15224856
references: J Acoust Soc Am. 2000 Mar;107(3):1637-44
references: 10738817
references: J Assoc Res Otolaryngol. 2004 Mar;5(1):11-24
references: 14605920
references: Hear Res. 2005 Feb;200(1-2):73-86
references: 15668040
references: J Acoust Soc Am. 1994 Oct;96(4):2048-54
references: 7963020
references: Philos Trans R Soc Lond B Biol Sci. 1992 Jun 29;336(1278):367-73
references: 1354376
references: J Neurosci Methods. 2005 Feb 15;141(2):171-98
references: 15661300
references: Laryngoscope. 2006 Aug;116(8):1310-20
references: 16885730
references: Hear Res. 2008 Jan;235(1-2):23-38
references: 18037252
references: Hear Res. 2005 Apr;202(1-2):55-62
references: 15811699
references: Hear Res. 1987;29(2-3):195-206
references: 3624083
references: IEEE Trans Biomed Eng. 1977 Jan;24(1):59-63
references: 851475
references: Hear Res. 1999 Jan;127(1-2):108-18
references: 9925022
references: Hear Res. 2006 Oct;220(1-2):49-60
references: 16904278
references: J Assoc Res Otolaryngol. 2006 Sep;7(3):253-66
references: 16715356
references: J Neurophysiol. 2008 Jul;100(1):92-107
references: 18450583
references: Otolaryngol Head Neck Surg. 1981 Jan-Feb;89(1):125-30
references: 6784070
references: Annu Rev Biomed Eng. 2008;10:275-309
references: 18429704
references: Audiol Neurootol. 2004 Nov-Dec;9(6):341-52
references: 15467287
references: J Acoust Soc Am. 1983 Apr;73(4):1283-92
references: 6687893
references: J Acoust Soc Am. 1999 Feb;105(2 Pt 1):850-60
references: 9972570
references: IEEE Trans Biomed Eng. 1996 Aug;43(8):857-65
references: 9216159
references: Hear Res. 2008 Aug;242(1-2):154-63
references: 18468821
references: Ear Hear. 1999 Feb;20(1):60-74
references: 10037066
references: J Acoust Soc Am. 2004 Oct;116(4 Pt 1):2258-68
references: 15532657
references: Otol Neurotol. 2003 Jul;24(4):590-5
references: 12851550
references: J Acoust Soc Am. 2007 Mar;121(3):1642-53
references: 17407901
references: Brain Res. 2000 Jun 30;869(1-2):251-5
references: 10865084
references: Hear Res. 1996 May;95(1-2):33-48
references: 8793506
references: Arch Otolaryngol. 1977 Dec;103(12):691-9
references: 588122
references: Hear Res. 2008 Aug;242(1-2):141-53
references: 18501539
references: Psychon Bull Rev. 2004 Feb;11(1):192-6
references: 15117008
references: J Acoust Soc Am. 1998 Nov;104(5):2570-7
references: 9821336
references: Neuroreport. 1999 Jun 23;10(9):1931-5
references: 10501535
references: Ann Biomed Eng. 1979;7(2):117-25
references: 533020
references: IEEE Trans Biomed Eng. 1987 Nov;34(11):883-90
references: 3692506
references: Hear Res. 2005 Jul;205(1-2):210-24
references: 15953530
references: Hear Res. 2010 Sep 1;268(1-2):93-104
references: 20580801
references: Hear Res. 1998 Jul;121(1-2):11-28
references: 9682804
references: Hear Res. 1988 Aug;34(3):267-74
references: 3170367
references: J Assoc Res Otolaryngol. 2007 Mar;8(1):42-53
references: 17160638
references: J Acoust Soc Am. 1999 Oct;106(4 Pt 1):1917-24
references: 10530016
references: J Acoust Soc Am. 2007 Aug;122(2):967-81
references: 17672645
references: Hear Res. 1985 May;18(2):135-43
references: 3840159
references: J Assoc Res Otolaryngol. 2004 Sep;5(3):305-22
references: 15492888
references: Hear Res. 2005 Apr;202(1-2):170-9
references: 15811709
references: J Acoust Soc Am. 1996 Oct;100(4 Pt 1):2393-414
references: 8865646
references: Adv Otorhinolaryngol. 2006;64:31-49
references: 16891835
references: Hear Res. 2009 Apr;250(1-2):46-54
references: 19450432
references: J Assoc Res Otolaryngol. 2005 Sep;6(3):269-79
references: 16075190
references: Neuroreport. 2002 Sep 16;13(13):1635-9
references: 12352617
references: J Neurophysiol. 2002 Jan;87(1):478-92
references: 11784764