Accuracy of the NDI Wave Speech Research System PurposeThis work provides a quantitative assessment of the positional tracking accuracy of the NDI Wave Speech Research System.MethodThree experiments were completed: (a) static rigid-body tracking across different locations in the electromagnetic field volume, (b) dynamic rigid-body tracking across different locations within the electromagnetic field volume, and (c) human jaw-movement tracking ... Research Note
Research Note  |   October 01, 2011
Accuracy of the NDI Wave Speech Research System
 
Author Notes
  • Correspondence to Jeffrey J. Berry: jeffrey.berry@marquette.edu
  • Editor: Anne Smith
    Editor: Anne Smith×
  • Associate Editor: David McFarland
    Associate Editor: David McFarland×
Article Information
Speech, Voice & Prosody / Speech
Research Note   |   October 01, 2011
Accuracy of the NDI Wave Speech Research System
Journal of Speech, Language, and Hearing Research, October 2011, Vol. 54, 1295-1301. doi:10.1044/1092-4388(2011/10-0226)
History: Received August 14, 2010 , Accepted January 28, 2011
 
Journal of Speech, Language, and Hearing Research, October 2011, Vol. 54, 1295-1301. doi:10.1044/1092-4388(2011/10-0226)
History: Received August 14, 2010; Accepted January 28, 2011
Web of Science® Times Cited: 27

PurposeThis work provides a quantitative assessment of the positional tracking accuracy of the NDI Wave Speech Research System.

MethodThree experiments were completed: (a) static rigid-body tracking across different locations in the electromagnetic field volume, (b) dynamic rigid-body tracking across different locations within the electromagnetic field volume, and (c) human jaw-movement tracking during speech. Rigid-body experiments were completed for 4 different instrumentation settings, permuting 2 electromagnetic field volume sizes with and without automated reference sensor processing.

ResultsWithin the anthropometrically pertinent “near field” (< 200 mm) of the NDI Wave field generator, at the 300-mm3 volume setting, 88% of dynamic positional errors were < 0.5 mm and 98% were < 1.0 mm. Extreme tracking errors (> 2 mm) occurred within the near field for < 1% of position samples. For human jaw-movement tracking, 95% of position samples had < 0.5 mm errors for 9 out of 10 subjects.

ConclusionsStatic tracking accuracy is modestly superior to dynamic tracking accuracy. Dynamic tracking accuracy is best for the 300-mm3 field setting in the 200-mm near field. The use of automated head correction has no deleterious effect on tracking. Tracking errors for jaw movements during speech are typically < 0.5 mm.

Acknowledgments
This study was supported by start-up funds from Marquette University and the 2009–2010 Marquette University Research Development Program Award. Portions of this study were presented at the 2010 Conference on Motor Speech, Savannah, GA.
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