J Am Acad Audiol 2020; 31(03): 195-208
DOI: 10.3766/jaaa.18092
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Sound Localization in Toddlers with Normal Hearing and with Bilateral Cochlear Implants Revealed Through a Novel “Reaching for Sound” Task

Erica E. Bennett
*   Henry Ford Health System, Detroit, MI
†   Waisman Center, University of Wisconsin-Madison, Madison, WI
Ruth Y. Litovsky
†   Waisman Center, University of Wisconsin-Madison, Madison, WI
› Author Affiliations
Further Information

Publication History

02 June 2019

09 June 2019

Publication Date:
24 May 2020 (online)



Spatial hearing abilities in children with bilateral cochlear implants (BiCIs) are typically improved when two implants are used compared with a single implant. However, even with BiCIs, spatial hearing is still worse compared to normal-hearing (NH) age-matched children. Here, we focused on children who were younger than three years, hence in their toddler years. Prior research with this age focused on measuring discrimination of sounds from the right versus left.


This study measured both discrimination and sound location identification in a nine-alternative forced-choice paradigm using the “reaching for sound” method, whereby children reached for sounding objects as a means of capturing their spatial hearing abilities.

Research Design:

Discrimination was measured with sounds randomly presented to the left versus right, and loudspeakers at fixed angles ranging from ±60° to ±15°. On a separate task, sound location identification was measured for locations ranging from ±60° in 15° increments.

Study Sample:

Thirteen children with BiCIs (27–42 months old) and fifteen age-matched (NH).

Data Collection and Analysis:

Discrimination and sound localization were completed for all subjects. For the left–right discrimination task, participants were required to reach a criterion of 4/5 correct trials (80%) at each angular separation prior to beginning the localization task. For sound localization, data was analyzed in two ways. First, percent correct scores were tallied for each participant. Second, for each participant, the root-mean-square-error was calculated to determine the average distance between the response and stimulus, indicative of localization accuracy.


All BiCI users were able to discriminate left versus right at angles as small as ±15° when listening with two implants; however, performance was significantly worse when listening with a single implant. All NH toddlers also had >80% correct at ±15°. Sound localization results revealed root-mean-square errors averaging 11.15° in NH toddlers. Children in the BiCI group were generally unable to identify source location on this complex task (average error 37.03°).


Although some toddlers with BiCIs are able to localize sound in a manner consistent with NH toddlers, for the majority of toddlers with BiCIs, sound localization abilities are still emerging.

This research was funded by a grant from the NIH-NIDCD (Grant No. 5R01DC00835) to Ruth Litovsky and in part by a core grant to the Waisman Center from the NIH-NICHD (Grant No. P30 HD03352).


  • Ashmead D, Clifton RK, Perris E. 1987; Precision of auditory localization in human infants. Dev Psychol 23 (05) 641-647
  • Ashmead D, Davis D, Whalen T, Odom R. 1991; Sound localization and sensitivity to interaural time differences in human infants. Child Dev 62: 1211-1226
  • Baumgärtel R, Hu H, Kollmeier B, Dietz M. 2017; Extent of lateralization at large interaural time differences in simulated electric hearing and bilateral cochlear implant users. J Acoust Soc Am 141 (04) 2338-2352
  • Blauert J. 1987; Spatial hearing: the psychophysics of human sound localization by Jens Blauert. J Acoust Soc Am 77 (01) 334-335
  • Chadha N, Papsin B, Jiwani S, Gordon K. 2011; Speech detection in noise and spatial unmasking in children with simultaneous versus sequential bilateral cochlear implants. Otol Neurotol 32 (07) 1057-1064
  • Clifton R, Morrongiello B, Kulig J, Dowd J. 1981; Newborns’ orientation toward sound: possible implications for cortical development. Child Dev 52 (03) 833-838
  • Clifton R, Gwiazda J, Bauer J, Clarkson MG, Held RM. 1988; Growth in head size during infancy: implications for sound localization. Dev Psychol 24: 477-483
  • Cullington HE, Bele D, Brinton JC, Cooper S, Daft M, Harding J, Hatton N, Humphries J, Lutman ME, Maddocks J, Maggs J, Millward K, O’Donoghue G, Patel S, Rajput K, Salmon V, Sear T, Speers A, Wheeler A, Wilson K. 2017; United Kingdom national paediatric bilateral project: results of professional rating scales and parent questionnaires. Cochlear Implants Int 18 (01) 23-35
  • Dorman M, Loizou P, Rainey D. 1997; Speech intelligibility as a function of the number of channels of stimulation for signal processors using sine-wave and noise-band outputs. J Acoust Soc Am 102 (04) 2403-2411
  • Dorman MF, Loiselle LH, Cook SJ, Yost WA, Gifford RH. 2016; Sound source localization by normal-hearing listeners, hearing-impaired listeners and cochlear implant listeners. Audiol Neurotol 21 (03) 127-131
  • Godar SM, Litovsky RY. 2010; Experience with bilateral cochlear implants improves sound localization acuity in children. Otol Neurotol 31 (08) 1287
  • Gordon K, Deighton M, Abbasalipour P, Papsin B. 2014; Perception of binaural cues develops in children who are deaf through bilateral cochlear implantation. PLoS One 9 (12) e114841
  • Gordon K, Jiwani S, Papsin B. 2013; a Benefits and detriments of unilateral cochlear implant use on bilateral auditory development in children who are deaf. Front Psychol 4: 719
  • Gordon K, Wong D, Papsin C. 2013; b Bilateral input protects the cortex from unilaterally-driven reorganization in children who are deaf. Brain 136 (05) 1609-1625
  • Grieco-Calub T, Litovsky R. 2010; Sound localization skills in children who use bilateral cochlear implants and in children with normal acoustic hearing. Ear Hear 31: 645-656
  • Grieco-Calub T, Litovsky R. 2012; Spatial acuity in 2-to-3-year-old children with normal acoustic hearing, unilateral cochlear implants, and bilateral cochlear implants. Ear Hear 33 (05) 561-572
  • Grieco-Calub T, Litovsky R, Werner L. 2008; Using the observer-based psychophysical procedure to assess localization acuity in toddlers who use bilateral cochlear implants. Otol Neurotol 29 (02) 235-239
  • Grieco-Calub T, Saffran J, Litovsky RY. 2009; Spoken word recognition in toddlers who use cochlear implants. J Speech Lang Hear Res 52 (06) 1390-1400
  • Hess C, Misurelli S, Litovsky R. 2018; Spatial release from masking in 2-year-olds with normal hearing and with bilateral cochlear implants. Trends Hear 22: 233121651877556
  • Kan A, Litovsky R. 2015; Binaural hearing with electrical stimulation. Hear Res 322: 127-137
  • Litovsky R. 1997; Developmental changes in the precedence effect: estimates of minimum audible angle. J Acoust Soc Am 102: 1739-1745
  • Litovsky R. 2011; Review of recent work on spatial hearing skills in children with bilateral cochlear implants. Cochlear Implants Int 12 (1, Suppl) S30-S34
  • Litovsky R.. 2015 Development of the auditory system.. In: Handbook of Clinical Neurology. Waltham, MA: Elsevier, pp. 55–72.
  • Litovsky R, Godar S. 2010; Difference in precedence effect between children and adults signifies development of sound localization abilities in complex listening tasks. J Acoust Soc Am 128 (04) 1979-1991
  • Litovsky RY, Gordon K.. 2016; Bilateral cochlear implants in children: Effects of auditory experience and deprivation on auditory perception. Hear Res 338: 76-87
  • Litovsky R, Ehlers E, Hess C, Harris S. 2013; Reaching for sound measures: an ecologically valid estimate of spatial hearing in 2- to 3-year-old children with bilateral cochlear implants. Otol Neurotol 34: 429-435
  • Litovsky R, Goupell MJ, Godar S, Grieco-Calub T, Jones GL, Garadat SN, Agrawal S, Kan A, Todd A, Hess C, Misurelli S. 2012; Studies on bilateral cochlear implants at the University of Wisconsin’s Binaural Hearing and Speech Laboratory. J Am Acad Audiol 23 (06) 476-494
  • Litovsky R, Johnstone PM, Godar S, Agrawal S, Parkinson A, Peters R, Lake J. 2006; a Bilateral cochlear implants in children: localization acuity measured with minimum audible angle. Ear Hear 27: 43-59
  • Litovsky R, Parkinson A, Arcaroli J, Sammeth C. 2006; b Simultaneous bilateral cochlear implantation in adults: a multicenter clinical study. Ear Hear 27: 714-731
  • Middlebrooks J, Green D. 1991; Sound localization by human listeners. Annu Rev Psychol 42: 135-159
  • Misurelli S.. 2014 An investigation of spatial hearing in children with normal hearing and with cochlear implants and the impact of executive function (dissertation). University of Wisconsin-Madison, Madison, WI
  • Misurelli S, Litovsky R. 2012; Spatial release from masking in children with normal hearing and with bilateral cochlear implants: effect of interferer asymmetry. J Acoust Soc Am 132: 380-391
  • Mok M, Galvin K, Dowell R, McKay C. 2009; Speech perception benefit for children with a cochlear implant and a hearing aid in opposite ears and children with bilateral cochlear implants. Audiol Neurotol 15: 44-56
  • Morrongiello B, Rocca P. 1990; Infants’ localization of sounds within hemifields: estimates of minimum audible angle. Child Dev 61 (04) 1258-1270
  • Muir D, Clifton R, Clarkson M. 1989; The development of a human auditory localization response: A u-shaped function. Can J Psychol 43 (02) 199-216
  • Murphy J, Summerfield Q, O’Donoghue G, Moore R. 2011; Spatial hearing of normally hearing and cochlear implanted children. Int J Pediatr Otorhinolaryngol 75 (04) 489-494
  • Olsho L, Koch E, Halpin C, Carter E. 1987; An observer-based psychoacoustic procedure for use with young infants. Dev Psychol 23 (05) 627-640
  • Peng ZE, Hess C, Saffran JR, Edwards JR, Litovsky RY. 2019; Assessing fine-grained speech discrimination in young children with bilateral cochlear implants. Otol Neurotol 40 (03) e191-e197
  • Perris E, Clifton R. 1988; Reaching in the dark toward sound as a measure of auditory localization in infants. Infant Behav Dev 11 (04) 473-491
  • Reeder R, Firszt J, Cadieux J, Strube M. 2017; A longitudinal study in children with sequential bilateral cochlear implants: time course for the second implanted ear and bilateral performance. J Speech Lang Hear Res 60 (01) 276-287
  • Steel M, Papsin B, Gordon K. 2015; Binaural fusion and listening effort in children who use bilateral cochlear implants: a psychoacoustic and pupillometric study. PLoS One 10 (02) e0117611
  • Van Deun L, Van Wieringen A, Scherf F, Deggouj N, Desloovere C, Offeciers FE, Van de Heyning PH, Dhooge IJ, Wouters J. 2009; Earlier intervention leads to better sound localization in children with bilateral cochlear implants. Audiol Neurotol 15 (01) 7-17
  • Van Deun L, van Wieringen A, Van den Bogaert T, Scherf F, Offeciers F, Van de Heyning P, Desloovere C, Dhooge I, Deggouj N, Raeve L, Wouters J. 2009; Sound localization, sound lateralization, and binaural masking level differences in young children with normal hearing. Ear Hear 30 (02) 178-190
  • Van Hoesel R. 2004; Exploring the benefits of bilateral cochlear implants. Audiol Neuro-Otol 9: 234-246
  • Zheng Y, Godar S, Litovsky R. 2015; Development of sound localization strategies in children with bilateral cochlear implants. PLoS One 10 (08) e0135790