Source filter Oct 11

Question 1

What is the source-filter theory?

Answer 1

This theory hypothesizes that an acoustic speech signal ca be seen as a source signal… filtered with the resonances in the cavities of the vocal tract…”

Question 2

what is the source?

Answer 2

the glottal course or noise generated at a constriction in the vocal tract

Question 3

What is the filter

Answer 3

the supralaryngeal cavitites

Question 4

what is a harmonic in terms of source filters

Answer 4

a simple wave (component frequency) that is available in the source signal

Question 5

How many harmonics do speech signals have

Answer 5

theoretically speaking signals can have infinite number of harmonics

Question 6

Can we calculate harmonics from a voiceless fricative?

Answer 6

No, because voiceless fricative are generated by aperiodic airflow, whereas voiced sounds use periodic source. voiced sounds have a fundamental frequency F0 which is the first harmonic, harmonics are just multiples of the fundamental frequency therefore if there is not fundamental frequency we can’t have harmonics.

Question 7

what are the 3 concepts of filtering

Answer 7

high-pass filter, low-pass filter, band-pass filter

Question 8

what does pass band look like

Answer 8

the curves of the bell shape on either side are rejected bands.

Question 9

what is cut off for pass band

Answer 9

the lower and upper cut offs.

Question 10

after making a recording you now want to keep the frequencies from 200hz and above. what kind of filter do you use?

Answer 10

High-pass filter. Low- pass would do the opposite and band-pass would have 2 cut offs.

Question 11

what kind of fliter does our vocal tract act as

Answer 11

our vocal tract acts as a series of band-pass filters

Question 12

what is the center frequencies of our filters

Answer 12

they create formants

Question 13

what is a node

Answer 13

a particle that stays at zero and does not move.

Question 14

What is an anti-node

Answer 14

an antinode is a particle that oscillate a lot side to side.

Question 15

fundamental frequency/ wavelength for open- open tubes is

Answer 15

2 and the upside down Y

Question 16

fundamental frequency/ wavelength for open- closed tubes is

Answer 16

4 and the upside down Y

Question 17

what is the formula for wavelength of a tube with 2 sides open

Answer 17

Y=2L/n

Question 18

what is the formula for the wavelength of a tube that has one open end

Answer 18

Y=4L/(2n-1)

Question 19

why does the open-closed tube have denominator of (2n-1)

Answer 19

to ensure that it is always an odd number