resonance & tube models - exam 1

Question 1

resonant frequencies

Answer 1

frequencies at which the vocal tract naturally amplifies sound waves

Question 2

formants

Answer 2

specific resonant frequencies of the vocal tract that shape the acoustic properties of vowels & other speech sounds

Question 3

what does F1 relate to

Answer 3

the height of the tongue

Question 4

what does the F2 relate to

Answer 4

advancement of the tongue

Question 5

what happens when a compression wave reflects on the closed end of a tube

Answer 5

it is reflected back as a compression wave

Question 6

what happens when a compression wave reflects off the open end of a tube

Answer 6

it is reflected back as a rarefaction wave

Question 7

standing waves

Answer 7

sound waves in a tube interacting & combining with incoming waves

forms consistent peaks & valleys

Question 8

single tube model

Answer 8

models the vocal tract as a single tube

ideal for understanding basic vowel production

Question 9

multi tube model

Answer 9

represents the vocal tract as a series of connected tubes

entire length is fixed, but can adjust each section
(front gets longer –> back gets shorter)

Question 10

resonance in a closed tube

Answer 10

1. 1st peak enters tube
2. 1st peak reaches halfway point
3. 1st peak reaches end & reflects
   1st trough enters tube
4. reflected peak reaches halfway point
   1st trough reaches halfway point
5. reflected peak reaches speaker again
   1st trough reaches the end & reflectes
   2nd peak enters tube

Question 11

what is the pressure in the middle of a closed tube

Answer 11

always zero - the waves are cancelling each other out

particles are moving the most

Question 12

where is pressure zero in a closed-open tube

Answer 12

at the open end

Question 13

helmholtz resonator

Answer 13

model of sound resonance in a cavity w/ a narrow opening (like vocal tract)

crucial in shaping low-freq sounds

glass bottle shape - large closed back cavity
small closed open front cavity

Question 14

how to calculate resonance in closed tube

Answer 14

fn = nc/2L

n = the harmonic number
c = the speed of sound (35000)
L = length of the tube

Question 15

how to calculate resonance for a closed open tube

Answer 15

fn = (2n-1)c / 4L

(2n-1) = odd numbers

1 = 1
2 = 3
3 = 5
4 = 7

Question 16

source & filter are dependent

Answer 16

formants do not depend on harmonics

Question 17

envelope

Answer 17

broad shape of the wave

peaks = formants

Question 18

are formants equally spaced

Answer 18

no

Question 19

2 closed open tubes

Answer 19

skinny tube in the larynx = back cavity
- closed-open

fat tube in the mouth = front cavity
-closed-open
(technically open where glottis connects, but opening so small it doesn’t really matter)

Question 20

can we set L the length of a complex tube

Answer 20

no

sound waves travel differently in different sized tubes so they need to be measured separately

Question 21

as a cavity lengthens, the frequencies get…?

Answer 21

lower

Question 22

why do shorter cavities have higher freqs

Answer 22

shorter tube takes less time to reflect

want to put energy in more often

more often = more frequent = higher frequency

higher frequency = higher pitch

Question 23

how to find formants on a nomogram

Answer 23

lowest resonance on graph = F1

second lowest = F2

third lowest = F3

Question 24

which tube contributes the formants

Answer 24

the longer one

longer = lower

Question 25

i am sitting in a room - what was it

Answer 25

same recording played over & over again in a room

eventually sound distorted into resonant hums

Question 26

i am sitting in a room - why

Answer 26

the resonant freqs of the room kept amplifying each other