Comd 5070 Speech Science Week 2 Of 5 Exam 1

Front 1

A low pass filter
a) restores the frequencies removed by a high pass filter
b) has no effect on speech
c) makes fricatives like /s/ easier to understand
d) holds back/removes high frequency components in a signal
e) amplifies mid frequency components in a signal

Back 1

d) holds back/removes high frequency components in a signal

Front 2

A low pass filter

1. removes low frequencies
2. has no effect on a speech recording
3. blocks high frequencies
4. amplifies vowels
5. none of the above

Back 2

3. blocks high frequencies

Front 3

Electrical analog signals

1. are too vague to be used in science
2. are discrete in amplitude and time
3. are not found in modern recording environments
4. represent a phenomenon by the movement of electrons in a wire
5. are conceptually identical to digital signals

Back 3

4. represent a phenomenon by the movement of electrons in a wire

Front 4

What is digital sound?

Back 4

Note how music on compact discs sounds better than audiotape:
•“it’s different”
•“it’s clearer”
•“it’s more convenient –no rewinding”
•“it’s better”

Front 5

It’s not the sound itself that is digital –it’s the way we ____ the sound signal. Digital ______ tends to make a clearer, higher quality ____ of the sound.

Back 5

store, storage, copy

Front 6

Can your ears hear digits?

Back 6

No. The music is stored in numeric form but it is played back in analog form.

Front 7

What does ‘analog’ mean?

Back 7

‘Analog’ means ‘analogy’ –one phenomenon is represented by another.

Front 8

Example of analogous -

Back 8

The microphone’s sound signal that travels through a wire is analogous to, or represents the sound pressure coming through the air that reaches the microphone.

Front 9

•The microphone voltage represents sound:
•large positive voltage = air ______
•large negative voltage = air _______

Back 9

compression, rarefaction

Front 10

ANALOG SIGNALS:
most important characteristic of analog signals is that they are (2)

Back 10

-continuous in time
-continuous in amplitude

Front 11

Would you find any gaps in an analog recording?

Back 11

No

Front 12

An analog recording can represent: (2)

Back 12

•an infinite number of points in time
•an infinite number of amplitude values between the minimum and the maximum

Front 13

An analog signal ____ be fully represented by a table of numbers.

WHY?

What can show it accurately?

Back 13

cannot

because:
(irrational number)
table of numbers represents the amplitude at a given time, and you cannot have an infinite number of rows to reflect the infinite number of time intervals that there are in a truly continuous signal.

Only a graph could show it ‘truly’.

Front 14

A digital signal ____ be fully represented by a table of numbers.

Back 14

CAN

Front 15

Common analog instruments

Back 15

clock
mercury thermometer
tape measure
cassette recorder

Front 16

Digital recordings are ______:

Back 16

discrete

Front 17

How are digital recordings discrete? (2)

Back 17

in time
in amplitude

Front 18

digital signals are made up of a series of ___________ __________recorded in one long string

Back 18

separate numbers

Front 19

Are there any limitations of digital recordings, if so, what are they?

Back 19

The limitations of digital recordings are that there are ‘unknowns’ between the points.

Front 20

Can the limitations of digital recordings be overcome?

Back 20

But actually, if the individual sample points are close enough together in time, it is almost as if the sample were continuous.

Front 21

COMMON DIGITAL DEVICES

Back 21

digital clock

--numerical display can have various levels of detail…
•am or pm?
•hours?
•minutes?
•seconds?
•1/10ths or 1/100ths?

Front 22

HOW DOES A SOUND BECOME DIGITAL?

Back 22

The analog signal from the wire has to be converted to numbers in order to be used by a computer, etc. , and vice versa:

analog to digital (ADC) conversion (ex: from microphone to computer)

digital to analog (DAC) conversion (ex: from CD to speakers)

Front 23

Sampling rate=

Back 23

the frequency with which the numbers are recorded to represent amplitude values of the sound you are recording.

Front 24

How often do you take each snapshot for the sample?

Back 24

The more samples/snapshots you take, the better you can represent the original signal.

Front 25

The frequency of snapshots in a digital recording is called the

Back 25

Sampling rate

Front 26

The sample rate is specified in?
Example?

Back 26

Hz

Ex: If you take 10 samples/snapshots in a second, that would be a 10 Hz recording.

Front 27

SELECTING A SAMPLING RATE

A higher sampling rate gives better fidelity,

BUT (3 disadvantages)

Back 27

BUTA higher sampling rate requires bigger files, which require:
•more memory usage
•more disk space for storage
•more processing time for computation

Front 28

Part of your decision making regarding the sample rate will involve the?

Back 28

NYQUIST FREQUENCY

Front 29

what is the NYQUIST FREQUENCY

Back 29

The ‘Nyquist’ frequency is half the sample rate.

Front 30

What does the NYQUIST FREQUENCY
represent?

Back 30

highest frequency you can record and then accurately play back

Front 31

How to decide the Nyquist frequency?

Example

Back 31

You must find out the frequencies that are of interest to you–do you want to go up to 10 KHz, 20 KHz? Then you must double that number to choose a sample frequency.

Example:
For example, if you want to record a signal accurately up to 100 hz, you must sample at 200 Hz.

Front 32

The highest quality setting gives you the ______ amount of time to record, because high quality uses ____ data and takes ____ space on the device.

Back 32

shortest, more, more

Front 33

Higher sampling rate =

Back 33

higher quality

Front 34

ACOUSTIC ANALYSIS
Getting good data: (4)

SQMS

Back 34

Quiet Recording Environment
Use a quality microphone
Good Signal Strength
Proper Sample Rate

Front 35

Avoid driving the signal strength in a recording - otherwise you will have a ___________ sensation on the sample.

Back 35

clipping

Front 36

All Sounds Originate With Movement, EXAMPLE:
oscillation of the____ ____ chop the air into small pulses; they oscillate the air in the vocal tract as well as the air between the speaker and listener

Back 36

vocal folds

Front 37

Speech Production Has Many Degrees Of Freedom: Ex: The voice can do one thing, the ______ in the vocal tract can do another, and there are many different elements that can be individually adjusted to create the exact sound that you hear.

Back 37

articulators

Front 38

Benefits of Acoustic Analysis: (2)

Back 38

Acoustic Analysis Is Noninvasive

We Can Draw Inferences From The Changes In The Acoustic Signal About Movements That Generated The Sound

Front 39

disordered voice… indicates disordered vocal fold movement means a change in the ____ _____

Back 39

sound source.

Front 40

distorted/imprecise articulation… indicates abnormal movement of the articulators –a change in the ______

Back 40

filter

Front 41

Limitations of Acoustic Analysis (2)

Back 41

1) Motor Equivalence
(the same sound can be produced several physical ways. You could move the articulators in slightly different ways and still have the same end result. Acoustic analysis cannot always distinguish between these different types of movements with any level of precision)
2) Acoustics cannot reveal all details of Movement
(You can’t tell how many mm a tongue moved upward or forward when a person articulated a given sound. This doesn’t mean acoustic analysis isn’t useful;)

Front 42

Filtering - what does it do? Speech Filter?

Back 42

-remove certain things
A speech filter allows us to be selective in which frequencies we keep for analysis (simulate hearing loss with this)

Front 43

4 types of Filters:

Back 43

High Pass
Low Pass
Band Pass
Band Reject

Front 44

What is a High Pass Filter?

Back 44

allows high frequencies through–holds back lower frequencies

Front 45

What is a Low Pass Filter?

Back 45

allows low frequencies through–holds back higher frequencies

Front 46

What is a Band Pass Filter?

Back 46

allows a middle band of frequencies through–holds back both higher and lower frequencies

Front 47

What is a Band Reject Filter?

Back 47

holds back a middle band of frequencies–allows both higher and lower frequencies through

Front 48

Why use a Band Pass Filter?

Back 48

Show Each Frequency and Its Energy.These were used in the early days of speech analysis because they helped us understand which frequencies were present in the speech sample.

to understand whether the energy was in the lower part of the frequency range, the middle range, or the higher range for a certain sound

Front 49

Why use a Band Reject Filter?

Back 49

Remove Unwanted Noise

Front 50

information about the strength of the different frequencies in a given sound - what kind of filter would help you?

Back 50

Band Pass Filter - Analysis via Fixed Filters

Front 51

You could move from low to high frequencies as the frequency energy was being analyzed - what kind of method/filter would you use?

Back 51

Analysis via Adjustable Filter - Band Pass filter

Front 52

acoustic analysis is a little like looking for the ______ in a complex sound - and the ratios of _____ much like baking

Back 52

ingredients, ingredients

Front 53

Who came up with the FOURIER THEOREM

Back 53

FOURIER THEOREM - Joseph Fourier was a French mathematician & physicist : 1768-1830.

Front 54

What is the way of analyzing complex signals and decomposing them or splitting them into a series of component frequencies.

Back 54

FOURIER THEOREM

Front 55

Whose great contribution was to show that even complex sounds can be broken down into their individual sinusoid components?

Back 55

Joseph Fourier

Front 56

All periodic sounds are made of a combination of sine waves. (component frequencies) These individual sine waves may vary by (3)

Back 56

Amplitudes
Phase Angles
Frequencies