phonation measurement 2

Question 1

are vocal fold vibrations period or aperiodic?

Answer 1

periodic

Question 2

what might VF duration that gets longer periodically and then resets indicate?

Answer 2

parkinson’s disease (7-12Hz tremor frequency)

Question 3

normal variability in F0/pitch (jitter)?

Answer 3

0.2-1%

Question 4

normal variability in waveform amplitude/loudness (shimmer)?

Answer 4

<0.5dB or 2-5%

Question 5

normal variability for harmonics to noise ratio (HNR)?

Answer 5

15-40 HNR, anything below 13 = hoarseness

Question 6

T or F: photoglottography and electroglottography are direct measures of jitter, shimmer, VOT, HNR etc…

Answer 6

false – indirect

Question 7

how does photoglottography work? (2)

Answer 7

• illuminates trachea from below
• light-sensitive cell positioned above glottis in pharynx detects light passing through glottis

Question 8

what are some issues with photoglottography? (3)

Answer 8

• amount of light
• vertical movements or larynx
• interference of tongue

Question 9

if you know that the VFs have 3 cycles within 25msec, how would you calculate F0?

Answer 9

• F0 = cycles in 1 second
• 25msec x 40 = 1sec
• 3 cycles x 40msec = 120Hz

Question 10

how does electroglottography work?

Answer 10

• place 2 electrodes on neck, over VFs (right and left)
• VFs close= voltaege increases, VFs
  open voltage decreases

Question 11

what are low frequency direct current (DC) changes in resistance associated with? what about high frequency DC changes in resistance?

Answer 11

• low: vertical larynx movement (swallowing, respiration, articulation…)
• high: VF vibrations proper (Lx signal)

Question 12

how would we get the Lx component from larynx C?

Answer 12

• high pass filter
• VF vibration is normally at least above 70Hz

Question 13

is EGG more accurate than waveforms in detecting VF movements?

Answer 13

• yes
• can even detect pre-phonation initial VF position

Question 14

which end do VFs start to close from, anterior or posterior?

Answer 14

posterior

Question 15

how is glottal width measured?

Answer 15

by light (not EGG)

Question 16

how do we increase subglottal pressure?

Answer 16

keep VFs closed for longer

Question 17

if closing time increases, what happens to speed quotient? what about open quotient?

Answer 17

both become smaller (bc denominator is getting bigger)

Question 18

if you see an EGG signal characterized by a distinctive peak before the maximum amplitude, what does this suggest?

Answer 18

VF nodules

Question 19

how does the angle of the thyroid lamina vary between males and females?

Answer 19

wider in females

Question 20

how can we directly measure laryngeal behaviour?

Answer 20

laryngeal photography (cameras, scopes)

Question 21

why is aliasing a problem in measuring laryngeal movements with a camera?

Answer 21

• if sampling rate matches frame rate, no movement is seen
• if sampling rate is too low, not capturing enough movement
• if oversampling, see in slow motion

Question 22

T or F: flexible fiber optic endoscopes interfere with normal speech and show poor view of the VFs

Answer 22

false – do not interfere with speech, show best unobstructed view of VFs if positioned at level of epigloti=tis

Question 23

endoscopy is often used in combination with ____ to create synthetic representative images of glottal movements.

Answer 23

stroboscopy

Question 24

what does electromyography measure?

Answer 24

laryngeal muscle contractions (electrical potentials)