Lecture 11

Question 1

What kind of graph is used for analysing speech? What does it show?

Answer 1

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Question 2

What does a Spectrogram show?

Answer 2

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Question 3

What are the important quantities in sound?

Answer 3

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Question 4

What is the idea behind Fourier transforms?

Answer 4

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Question 5

What are the features of periodic signals? What makes a signal periodic?

Answer 5

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Question 6

What is the fundamental period?

Answer 6

saddasfa

Question 7

What are simple functions that represent periodic signals? How to map this onto a graph?

Answer 7

asadasfa

Question 8

What can any periodic signals be a sum of?

Answer 8

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Question 9

What is the Fourier series? What is the equation?

Answer 9

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Question 10

Why is just cos used?

Answer 10

ASASAD

Question 11

What variable change would make the approximation of a signal better using the Fourier Series?

Answer 11

sadsasfa

Question 12

What formula can be used to rewrite the Fourier Series equation?

Answer 12

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Question 13

What is Euler’s formula?

Answer 13

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Question 14

How to rewrite the Fourier’s series? What is the resulting formula called?

Answer 14

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Question 15

How to compute the coefficients? What is the theorem?

Answer 15

sadaf

Question 16

What to do for signals that are not periodic? How to represent?

Answer 16

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Question 17

What is a Fourier Transform? What is it used for?

Answer 17

saadfaf

Question 18

What are the formulas?

Answer 18

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Question 19

What is a property of Fourier transforms to analyse audio signals?

Answer 19

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Question 20

What is time-frequency uncertainty? What is the trade off?

Answer 20

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Question 21

If a signal is more localised in time what does that mean for the frequency?

Answer 21

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Question 22

What are most signals in the form of to read it from a computer?

Answer 22

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Question 23

What is sampling? What is it used for?

Answer 23

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Question 24

What is a sampling frequency? What happens if sampling at smaller sampling frequency? What is a consequence of this?

Answer 24

asasasas

Question 25

What is the Nyquist criterion? What are the properties of this sampling theorem?

Answer 25

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Question 26

What happens if sample too slowly?

Answer 26

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Question 27

What is aliasing? How to avoid this? Why does this happen in real life?

Answer 27

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Question 28

How does the low-pass filter work?

Answer 28

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Question 29

What is a Discrete Fourier Transform (DFT)? Why do we have to use it?

Answer 29

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Question 30

What is the process of a DFT? What are the stages?

Answer 30

asadad

Question 31

What are the equations of DFT?

Answer 31

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Question 32

What do you get when you compute the DFT to a sample speech? What is the result? What are the significant components of the results?

Answer 32

assas

Question 33

What is a short-time Fourier Transform (STFT)? What is it used to look at?

Answer 33

asadasd

Question 34

How to look at a particular part of a signal? What is the function?

Answer 34

sasads

Question 35

What is a the widowing function? What is the problem with this function? What is the solution for this?

Answer 35

sdasdas

Question 36

What is the trick used for a spectrogram? What is the result?

Answer 36

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Question 37

What is the fundamental frequency? What is it modified with?

Answer 37

sasaffsa

Question 38

What would the ideal type of windowing function Fourier transform? What are the components?

Answer 38

sadasd

Question 39

What are the different types of windowing functions? What are the advantages and disadvantages of each?

Answer 39

sadasda