Acoustic Aspects of Place Contrasts in Children with Cochlear ImplantsKelly Wagner, M.S., & Peter Flipsen Jr., Ph.D. Idaho State University

INTRODUCTION• Cochlear implants (CIs) provide individuals with

significant hearing loss access to sound that is different from normal hearing.

• Individuals who learn speech solely from CIs may do so differently than typical speakers.

• The current study used acoustic analysis to examine selected speech sound contrasts relative to place of articulation in the speech of 17 deaf children fitted with CIs.

METHOD• Participants included 4 males and 13 females born

with severe to profound bilateral hearing loss. • No other known handicaps.

• Implantation age ranged from 1;2 to 8;4 (Mn = 3;9).

• At time of testing the children ranged in age from 4;8 to 11;1 (Mn = 8;0).

• At time of testing implant experience ranged from 1;0 to 7;10 (Mn = 4;3).

• As part of a larger protocol, the children named pictures presented by a trained graduate student examiner.

• Targets were a subset of the words from the Minimal Pairs Production Task (MPPT; Chin, Finnegan, & Chung, 2001). • pie/tie pea/key pat/cat fell/shell

METHOD (cont’d)• Samples were recorded on digital audiotape

in a single wall sound treated booth.• Recordings were parsed into single word

files using CSL 3.4.0 and analyzed using WaveSurfer 1.8.4.

• Place contrasts were examined by looking at:• Spectral peak, spectral moments (mean,

variance, skew, kurtosis), VOT, and relative amplitude.

• Statistical tests were conducted with p < .05.

RESULTS• As a group, the speakers appeared to have

been using the following features contrastively:

Acknowledgments

Many thanks to Julie Beeler, Velvet Buehler, Molly Erickson, Mark Hedrick, Marge Hudson, Gayla Hutsell, Kim Jenkins, Leslie Jolles, Christopher Loether, Tony Seikel, and Saneta Thurman for their assistance. Special thanks to Rhonda Parker for participant testing. Many thanks also to the children and their parents who participated.

ASHA 2012

DISCUSSION• Phonemes in this study that do not correlate well with

normative data (/k/, /f/, and /C/) are also those that frequently present problems for children with hearing impairments, either because the oral movements are difficult to see or because they are distinguished by their high frequency spectrum.

• Speakers in this study succeeded in differentiating between place contrasts, but not necessarily in the same way as their normal-hearing peers.

• Given similarities to normative values, moments analysis may be an appropriate tool for assessing disordered speech and identifying subphonemic contrasts.

• A larger, more homogeneous sample is needed.

REFERENCES• Chin, S. B., Finnegan, K. R., & Chung, B. A. (2001). Relationships among types of

speech intelligibility in pediatric users of cochlear implants. Journal of Communication Disorders, 34, 187-205.

• Forrest, K., Weismer, G., Hodge, M., Dinnsen, D., & Elbert, M. (1990). Statistical analysis of word-initial /k/ and /t/ produced by normal and phonologically disordered children. Clinical Linguistics & Phonetics, 4, 4, 327-340.

• Forrest, K., Weismer, G., Milenkovic, P., & Dougall, R. (1988). Statistical analysis of word-initial voiceless obstruents: preliminary data. Journal of the Acoustical Society of America, 84, 1, 115-123.

• Jongman, A., Wayland, R., & Wong, S. (2000). Acoustic characteristics of English fricatives.Journal of the Acoustical Society of America, 108, 3(1), 1252-1263

• Nissen, S. L. (2003). An acoustic analysis of voiceless obstruents produced by adults and typically developing children. Unpublished doctoral dissertation.Columbus, Ohio: Ohio State University.

RESULTS (cont’d)

• Note differences for /k/, /C/, and /f/.• In subjective assessments, these same

speakers’ productions of /k/, /C/, and /f/ were judged to be correct > 90% of the time. This is similar to Forrest et al. (1990) and suggests that differences may persist even when the child’s error is “fixed”.

Atlanta, GA

RESULTS (cont’d) • Correlations were conducted with feature

distinctiveness and age of implantation, implant experience and chronological age. Results were limited and sometimes contradictory.• Age of implantation was sometimes

associated with greater distinctions between skew and spectral peak.

• Implant experience was sometimes associated with greater distinctions between relative amplitude; and less distinctiveness for variance, skew, mean and kurtosis.

• Chronological age was rarely associated with feature distinctiveness; when this did occur, older children tended to produce smaller distinctions overall. However, older speakers tended to be later implanted.

Comparisons to Normal Hearing Children

• Group averages were compared with data from Nissen (2003), who reported on normal hearing children.

 

VOTRelati

ve Durati

on

Word Durati

on

Relative

Amplitude

Spectral

MeanVariance

Skew

Kurtosi

s

Spectral

Peak

pat/ cat + + + +pie/ tie + + +

pea/ key + + + + + +fell/ shell + + + + + + +

/p/ /t/ /k/ /f/ /C/-15

-10

-5

0

Relative Amplitude

/p/ /t/ /k/ /f/ /C/0

50

100

150

200

250

VOT or Fricative Duration

VO

T (

ms)

/p/ /t/ /k/ /f/ /C/0

2000

4000

6000

8000

10000

Spectral Peak

Fre

quen

cy (

KH

z)

/p/ /t/ /k/ /f/ /C/0

1000200030004000500060007000

Spectral Mean

Fre

quen

cy (

KH

z)

/p/ /t/ /k/ /f/ /C/0

2

4

6

8

Variance

Var

ianc

e (M

Hz)

/p/ /t/ /k/ /f/ /C/-2.5

-1.5

-0.5

0.5

1.5

Skew

Skew

Nissen Wagner

400045005000550060006500

Average Spectral Mean

pietie

(overlapping 20-ms windows)

Freq

uenc

y (K

Hz)

Spectral mean distinguished all four word pairs from one another

0 2 4 6 8 1002468

1012

Age of Implant vs. Chronological Age

CE

Age at Implantation (Years)

Chro

nolo

gica

l Age

(Y

ears

)