D J Zajac

Summary

Affiliation: University of North Carolina
Country: USA

Publications

  1. ncbi Nasal coarticulation in normal speakers: a re-examination of the effects of gender
    D J Zajac
    University of North Carolina, Chapel Hill 27599, USA
    J Speech Lang Hear Res 41:503-10. 1998
  2. ncbi Maxillary arch dimensions and spectral characteristics of children with cleft lip and palate who produce middorsum palatal stops
    David J Zajac
    Craniofacial Center, University of North Carolina at Chapel Hill, NC, USA
    J Speech Lang Hear Res 55:1876-86. 2012
  3. ncbi Direct magnitude estimation of articulation rate in boys with fragile X syndrome
    David J Zajac
    University of North Carolina Craniofacial Center, Chapel Hill, NC, USA
    J Speech Lang Hear Res 52:1370-9. 2009
  4. ncbi Articulation rate and vowel space characteristics of young males with fragile X syndrome: preliminary acoustic findings
    David J Zajac
    University of North Carolina Craniofacial Center, CB 7450, Chapel Hill, NC 27599, USA
    J Speech Lang Hear Res 49:1147-55. 2006
  5. ncbi Aerodynamic characteristics of tracheostomy speaking valves: an updated report
    D J Zajac
    University of North Carolina at Chapel Hill, 27599, USA
    J Speech Lang Hear Res 42:92-100. 1999
  6. ncbi Pressure-flow characteristics of /m/ and /p/ production in speakers without cleft palate: developmental findings
    D J Zajac
    University of North Carolina at Chapel Hill, USA
    Cleft Palate Craniofac J 37:468-77. 2000
  7. ncbi Air pressure responses to sudden vocal tract pressure bleeds during production of stop consonants: new evidence of aeromechanical regulation
    David J Zajac
    Craniofacial Center, University of North Carolina, Chapel Hill, NC 27599, USA
    J Speech Lang Hear Res 47:784-801. 2004
  8. ncbi Temporal characteristics of aerodynamic segments in the speech of children and adults
    David J Zajac
    UNC Craniofacial Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
    Cleft Palate Craniofac J 39:432-8. 2002
  9. ncbi The relationship between spectral characteristics and perceived hypernasality in children
    R Kataoka
    UNC Craniofacial Center, University of North Carolina at Chapel Hill, 27599 7450, USA
    J Acoust Soc Am 109:2181-9. 2001
  10. ncbi Effects of vowel height and vocal intensity on anticipatory nasal airflow in individuals with normal speech
    L H Young
    University of North Carolina at Chapel Hill, USA
    J Speech Lang Hear Res 44:52-60. 2001

Research Grants

  1. Speech of Young Males with Fragile X Syndrome
    David J Zajac; Fiscal Year: 2010
  2. Speech of Young Males with Fragile X Syndrome
    David Zajac; Fiscal Year: 2009
  3. Speech Intelligibility Testing in Children with Repaired Cleft Palate
    David Zajac; Fiscal Year: 2007
  4. Early Assessment of Infants with Cleft Palate Following Surgical Repair
    David Zajac; Fiscal Year: 2007
  5. SPEECH AND RESPIRATORY AERODYNAMICS IN CLEFT PALATE
    David Zajac; Fiscal Year: 2003
  6. Speech of Young Males with Fragile X Syndrome
    David Zajac; Fiscal Year: 2009

Collaborators

Detail Information

Publications18

  1. ncbi Nasal coarticulation in normal speakers: a re-examination of the effects of gender
    D J Zajac
    University of North Carolina, Chapel Hill 27599, USA
    J Speech Lang Hear Res 41:503-10. 1998
    ..Implications relative to aspects of speech production and clinical practice are discussed...
  2. ncbi Maxillary arch dimensions and spectral characteristics of children with cleft lip and palate who produce middorsum palatal stops
    David J Zajac
    Craniofacial Center, University of North Carolina at Chapel Hill, NC, USA
    J Speech Lang Hear Res 55:1876-86. 2012
    ....
  3. ncbi Direct magnitude estimation of articulation rate in boys with fragile X syndrome
    David J Zajac
    University of North Carolina Craniofacial Center, Chapel Hill, NC, USA
    J Speech Lang Hear Res 52:1370-9. 2009
    ..To compare the perceived articulation rate of boys with fragile X syndrome (FXS) with that of chronologically age-matched (CA) boys and to determine segmental and/or prosodic factors that account for perceived rate...
  4. ncbi Articulation rate and vowel space characteristics of young males with fragile X syndrome: preliminary acoustic findings
    David J Zajac
    University of North Carolina Craniofacial Center, CB 7450, Chapel Hill, NC 27599, USA
    J Speech Lang Hear Res 49:1147-55. 2006
    ..The objective of this preliminary study was to determine articulation rate-one component of perceived speaking rate-and vowel space characteristics of young males with FXS...
  5. ncbi Aerodynamic characteristics of tracheostomy speaking valves: an updated report
    D J Zajac
    University of North Carolina at Chapel Hill, 27599, USA
    J Speech Lang Hear Res 42:92-100. 1999
    ..The results of these analyses suggest that although the inspiratory resistance to airflow was similar among various one-way speaking valves, some valves exhibit air loss during speech production...
  6. ncbi Pressure-flow characteristics of /m/ and /p/ production in speakers without cleft palate: developmental findings
    D J Zajac
    University of North Carolina at Chapel Hill, USA
    Cleft Palate Craniofac J 37:468-77. 2000
    ..The purpose of this study was to describe the pressure-flow characteristics of a large sample of speakers without cleft palate ranging in age from early childhood to young adulthood...
  7. ncbi Air pressure responses to sudden vocal tract pressure bleeds during production of stop consonants: new evidence of aeromechanical regulation
    David J Zajac
    Craniofacial Center, University of North Carolina, Chapel Hill, NC 27599, USA
    J Speech Lang Hear Res 47:784-801. 2004
    ..Implications for understanding speech production and the characteristics of individuals with velopharyngeal dysfunction are discussed...
  8. ncbi Temporal characteristics of aerodynamic segments in the speech of children and adults
    David J Zajac
    UNC Craniofacial Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
    Cleft Palate Craniofac J 39:432-8. 2002
    ..A secondary objective was to determine the within-speaker variability of the segments...
  9. ncbi The relationship between spectral characteristics and perceived hypernasality in children
    R Kataoka
    UNC Craniofacial Center, University of North Carolina at Chapel Hill, 27599 7450, USA
    J Acoust Soc Am 109:2181-9. 2001
    ..5 kHz) was associated with an increasing perceived hypernasality. These results suggest that the amplitudes of the three 1/3-octave bands are appropriate acoustic parameters to quantify hypernasality in the isolated vowel [i]...
  10. ncbi Effects of vowel height and vocal intensity on anticipatory nasal airflow in individuals with normal speech
    L H Young
    University of North Carolina at Chapel Hill, USA
    J Speech Lang Hear Res 44:52-60. 2001
    ..The results further suggest that anticipatory nasal airflow may be determined by the configuration of the oral cavity to a greater extent in women than in men. Theoretical and clinical implications are discussed...
  11. ncbi Intraoral pressure and velopharyngeal function
    R Mayo
    Division of Speech and Hearing Sciences, School of Medicine, UNC Craniofacial Center, Chapel Hill, North Carolina 27599 7450, USA
    Cleft Palate Craniofac J 35:299-303. 1998
    ..The objective of this study was to determine the influence of velopharyngeal (VP) inadequacy on respiratory speech compensations...
  12. ncbi Estimation of transpalatal nasalance during production of voiced stop consonants by noncleft speakers using an oral-nasal mask
    Emily L Bundy
    UNC Craniofacial Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
    Cleft Palate Craniofac J 43:691-701. 2006
    ..F1-derived nasalance appears to better reflect transpalatal effects. Clinical implications are discussed...
  13. ncbi The influence of acoustic and perceptual factors on perceived hypernasality in the vowel
    R Kataoka
    UNC Craniofacial Center, University of North Carolina at Chapel Hill, NC, 27599-7450 USA
    Folia Phoniatr Logop 53:198-212. 2001
    ..Voice quality deviation and a particular type of spectral change that related to the severity of hypernasality could be factors that influence perceived hypernasality...
  14. ncbi Velopharyngeal function in young and older adult speakers: evidence from aerodynamic studies
    D J Zajac
    Department of Dental Ecology, University of North Carolina at Chapel Hill 27599, USA
    J Acoust Soc Am 102:1846-52. 1997
    ..The nasal air volume results suggest a gender specific velopharyngeal declination effect. Implications for velar motor control strategies are discussed...
  15. ncbi Effects of altered fundamental frequency on nasalance during vowel production by adult speakers at targeted sound pressure levels
    Kerry C Mandulak
    Division of Speech and Hearing Sciences, Department of Allied Health Sciences, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 7190, USA
    Cleft Palate Craniofac J 46:39-46. 2009
    ..This study investigated the effects of altered fundamental frequency (F0) on nasalance levels of the vowels /i/ and /a/ produced by adults without cleft palate within a controlled sound pressure level (SPL) range...
  16. ncbi Effects of a pressure target on laryngeal airway resistance in children
    D J Zajac
    Craniofacial Center, Department of Dental Ecology, University of North Carolina at Chapel Hill, 27599, USA
    J Commun Disord 31:201-12; quiz 212-3. 1998
    ..It is suggested that use of a pressure target during estimation of LAR in children may provide additional data that more accurately reflect the aerodynamic integrity of the larynx. Implications for clinical assessment are discussed...
  17. ncbi Assessment of aspiration risk in stroke patients with quantification of voluntary cough
    C A Smith Hammond
    Duke University and Durham Veterans Affairs Medical, Durham, NC, USA
    Neurology 56:502-6. 2001
    ..It was hypothesized that aspirating stroke patients would have impaired objective measures of voluntary cough as compared with both nonstroke control subjects and nonaspirating stroke patients...
  18. ncbi Direct measurement of subglottic air pressure while swallowing
    Roxann Diez Gross
    Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
    Laryngoscope 116:753-61. 2006
    ..The primary purpose of this study was to determine if subglottic air pressure is generated during swallowing in a healthy, nontracheostomized person...

Research Grants10

  1. Speech of Young Males with Fragile X Syndrome
    David J Zajac; Fiscal Year: 2010
    ....
  2. Speech of Young Males with Fragile X Syndrome
    David Zajac; Fiscal Year: 2009
    ....
  3. Speech Intelligibility Testing in Children with Repaired Cleft Palate
    David Zajac; Fiscal Year: 2007
    ..abstract_text> ..
  4. Early Assessment of Infants with Cleft Palate Following Surgical Repair
    David Zajac; Fiscal Year: 2007
    ....
  5. SPEECH AND RESPIRATORY AERODYNAMICS IN CLEFT PALATE
    David Zajac; Fiscal Year: 2003
    ..It is possible, for example, that therapeutic techniques may be developed that incorporate specific respiratory strategies employed by speakers with cleft palate who exhibit acceptable speech characteristics. ..
  6. Speech of Young Males with Fragile X Syndrome
    David Zajac; Fiscal Year: 2009
    ....