Quiz 5 Flashcards
Visualizing sounds | DSP
Which of the following is TRUE about periodic and aperiodic waves in speech? (Two correct answers.)
A. All approximant sounds produce complex waves containing aperiodic waves.
B. Vowels typically produce periodic waves due to the regular vibration of the vocal folds.
C. Voiced fricatives contain both periodic and aperiodic components due to vocal fold vibration and turbulent airflow.
D. Voiceless fricatives produce periodic waves with clearly repeating patterns.
B. Vowels typically produce periodic waves due to the regular vibration of the vocal folds.
C. Voiced fricatives contain both periodic and aperiodic components due to vocal fold vibration and turbulent airflow.
How does adding multiple sine waves of different frequencies affect the resulting wave? (One correct answer.)
A. It produces a sine wave with an amplitude equal to the sum of the amplitudes of the original waves.
B. It eliminates the periodicity of the wave, making it completely aperiodic.
C. It generates a complex wave that combines the properties of the individual sine waves.
D. It always results in a simple sine wave with a higher frequency.
C. It generates a complex wave that combines the properties of the individual sine waves.
Which of the following statements about analog signals is TRUE? (Two correct answers.)
A. The digitization of analog signals involves storing all possible values continuously.
B. Analyzing analog signals is generally slower than analyzing digital signals due to their continuous nature.
C. Analog signals have a finite set of possible values for points in time.
D. To digitize analog signals, we must sample them at specific intervals, which means only some values are retained.
B. Analyzing analog signals is generally slower than analyzing digital signals due to their continuous nature.
D. To digitize analog signals, we must sample them at specific intervals, which means only some values are retained.
Which of the following statements about the sampling rate and its impact on digital signals is FALSE? (One correct answer.)
A. A sampling rate equal to the Nyquist limit is sufficient to perfectly reconstruct all components of the signal.
B. Increasing the sampling rate above twice the highest frequency of interest reduces aliasing.
C. A sampling rate lower than the Nyquist frequency causes aliasing, distorting the original signal.
D. The choice of sampling rate influences the storage space and processing power required for the digital signal.
A. A sampling rate equal to the Nyquist limit is sufficient to perfectly reconstruct all components of the signal.
Which of the following correctly describes the behavior of a sine wave function as the angle increases? (One correct answer.)
Correct answer:
A. The sine value increases continuously without oscillation as the angle increases beyond 90 degrees.
B. The sine value oscillates between -1 and +1, representing the ratio of the opposite side to the hypotenuse.
C. The sine value remains constant as the angle changes, representing a steady signal amplitude.
D. The sine value oscillates between -2 and +2, determining the amplitude of the wave.
B. The sine value oscillates between -1 and +1, representing the ratio of the opposite side to the hypotenuse.
Which of the following is true about quantization in digitizing analog signals? (Two correct answers.)
A. Quantization ensures that the signal retains its continuous nature even in digital form.
B. Increasing the bit depth improves the accuracy of representation and reduces quantization error.
C. Quantization ensures that the signal retains its continuous nature even in digital form.
D. Quantization introduces quantization noise/error due to rounding of signal values.
B. Increasing the bit depth improves the accuracy of representation and reduces quantization error.
D. Quantization introduces quantization noise/error due to rounding of signal values.
What is a complex wave?
Many sine waves combined into one
T or F : Sine waves are not always simple waves
F
Which kinds of speech sounds have PERIODIC waves?
- [a]
- [j]
- [k]
- [l]
- [a] - vowel
- [l] - sonorant
T or F : prevoicing has periodic waves but voiceless fricatives have aperiodic waves
T
What is periodicity in complex waves?
The entire period where complex waves start to end
Voiced fricatives have what kind of waves?
- Periodic
- Aperiodic
- Mixed
- Mixed
_____ amplitude _____ darkness ____ energy
- Greater; less; less
- Less; greater ; greater
- Low; low; low
- Greater; greater; greater
- Low; low
- Greater; greater
How are spectrum and waveform different in terms of the info their provide?
Waveforms don’t provide the F0, formants, etc.
How to change complex waves to power spectrum?
- Make a list of the sine waves from complex.
- Decompose the waves + their frequencies
- Graph - frequency on x-axis, amplitude on y-axis
What info do we get from a spectrum/waveform?
F0 - fundamental frequency
F1, F2 - formants
H1 = H0, individual harmonics
How do we find the formants?
Each peak represents a formant
In vowels, what does F1, and F2 represent
- F1 = Tongue height | High f1, low vowel
- F2 = tongue backness | High f1, front vowel
To calculate a spectrogram, can we use just one periodic wave
No, you need MANY samples
Broad band gives us ______ information and narrow band gives us ________ info
- Harmonic; formant
- formant; harmonic
- formant; harmonic
What is a sonorant?
a liquid, glide ([w]), or nasal
T or F : analog signals carry staggered points in time
F ; continuous
Digitizing analog data can be very slow and difficult to store because analog signals are _____
continuous
Which one does not involve analog signals?
A. light
B. your position (when moving between places)
C. photo captured on your phone
D. pressure
C. photo captured on your phone
What do we have to do to do analog-to-digital data analysis
sampling at specific intervals
How do we actually digitize 1 sine wave?
We have to store the AMPLITUDE in a function of TIME
Sampling rate is measured in :
- Dyne
- dB
- Hz
- Hz
What is the default sampling rate (Hint : found in PRAAT)?
44100 Hz
Nyquist’s Theorem
To prevent aliasing (the mistmatch of digitalization of waves), the sampling rate has to be AT LEAST DOUBLE the frequency - if you do this, you can recover the analog signals with no loss of info.
Nyquist’s Frequency/Limit
Highest frequency being recorded
Human speech are mostly distributed in frequencies under 5Hz. What sampling rate would you pick to capture frequencies up to this frequency?
A. 5,000 Hz
B. 10,000 Hz
C. 20,000 Hz
D. 15,000 Hz
B. 10,000 Hz
What frequency does speech usually go up to?
8000Hz
Sampling rate LOWER than Nyquists = ______
Aliasing
Anti-aliasing filter/low pass filter
Before the audio file gets sampled, the filter takes out any frequencies that go above 20k
T or F : if detailed enough, a sampled wave can be perfectly smooth
F : it will never be 100% smooth
Which of the following represents the average bit amount for sampling?
- 20bit
- 25bit
- 16bit
- 10bit
- 16bit
Quantization noise - when does it occur
The noise that occurs when transferring analog signals to digital signals - will happen no matter if you go UP or DOWN
Fourier transform - who can generate it
PRAAT or any sound analysis software
IS a mathematical analysis of a complex wave - looks at the degree of correlation between waves
You want to see if peaks follow peaks in diff Hz, and valleys too
What is the formula for sine function? What range do oscillations occur in?
sin() = Opposite/Hypotenuse
-1 to 1
Which of the following is the correct value for sin90?
- -1
- 0
- 1
- 1
(SINE) When a wave moves, an ______ is created
angle
