development of speech breathing
Emergence: birth to 3 years
-vocalizations on exhale
Refinement: 3 to adult
-increased lung size and volume; increased stiffness in airway and chest wall
Adaptation: older child to adult
-efficiency in speech breathing + more linguistically adept
differences in young child vs. older child vs. adult
- pressures for speech
- inhalation: Kids inhale more deeply
- lung volume when initiating speech: kids begin speaking at larger lung volumes
- end speech below REL
- kids use larger %age of vital capacity for speech
- older kids and adults use greater rib cage movement than abdominal
larynx in infancy and childhood
- developed by end of first trimester
- position C3-4 at birth; C6-7 at puberty
- cartilages and hyoid soft and flexible
- epiglottis bulky, omega-shaped
- VF 1.25-3 mm, tilt downward
- lamina propria undifferentiated
- narrowest portion is below VFs
infant vocalizations
- crying requires coordination of laryngeal, respiration & supralaryngeal muscles
- cries, coughs, burps = not much neuromuscular control over laryngeal function
- cry, short moan, wail, croak, laugh, coo, squeal, raspberyy = as baby matures
- squeals, growls and mid-vowels reflect first abilities to form phonemes
FO in infants
- maturation of neuro and physiologic systems as infant matures
- more muscle control means greater control over subglottal air pressure (changes in loudness)
- FO is higher in premies: smaller VF, more stressed by pain, increased tension
- FO is higher in babies with neuro diseases and malnourished
- FO lower in babies with apnea due to low muscle tone
5 preverbal stages
- 0-1 month: no systematic dif in open/close of VF
- 2-3 months: first appearance of laughing, vocal variations
- 4-6 months: vocal play, exploring sounds as squealing/growling, blowing saliva, air, food
- 7-10 months: babbling
- 11 months: babbling with alternating syllables, different Cs and Vs
childhood changes in voice
- larynx: increases in size, descends in neck
- VF: lengthen and layers differentiate
- acoustics: drops in FO from ages 6-14 in males and females; 100 Hz in males, 35 Hz in females
puberty
-laryngeal cartilages grown 2-3x more in males AP than females and weight; angle of thyroid increases to 90 degrees in males, stays 120 in females
-VF = 12 mm in males; 4 mm in females
-vocal ligament: continues to differentiate into layers
-larynx: descends to level of C6 or C7
(this lengthens VFs, lowers pitch and changes resonance)
-adolescent boys: pitch breaks, hoarse voice; age of onset 12.5-14.5; duration ave 18 mod
Adult female voice
- Adult female voice: breathiness due to posterior glottal gap
- fluctuations in quality - hormonal cycles
- estrogen increases secretions & reduces mucosal viscosity; dry voice
- progesterone reduces secretions, increases dehydration, increases mucosal viscosity, thinning of VF mucosa
- androgens cause irreversible masculinization of voice
voice changes caused by PMS, ovulation and pregnancy
-Premenstrual Vocal Syndrome: vocal fatigue decreased range loss of vocal power loss of higher harmonics -ovulation edema thick glandular secretions reduced amplitude of vibration vascular changes -pregnancy vocal fatigue hoarseness
aging voice - structural changes
-changes are gradual and variable
-females have menopause, loss of hydration & GERD
-structural changes:
cartilage: ossification
(thyroid > cricoid; men > women)
-joints
CT: pitch: CA: loudness
-muscles: speed, force, endurance of contractions; less innervation
-VF layers: epithelial and lamina propria (become dry)
aging voice - acoustic effects
- change in FO: increase in men (muscle tone), decrease in women (progesterone)
- decreased phonatory stability (ability to keep vibrations going)
- reduced intensity (laryngeal changes and respiratory factors)
- increased breathiness: can’t pull VF together as well
presbyphonia
term used for normally aging laryngeal mechanism
- auditory perceptual changes: altered pitch, hoarseness, breathiness, strain, slow rate
- visual-perceptual changes: bowing, atrophy, spindle-shaped gap, edema
- acoustic changes: increased FO in males, decreased FO in females; decreased intensity; increased NHR
