COMD 5070 EXAMS 1 AND 2 | ALL
QUESTIONS AND CORRECT
ANSWERS | ALREADY GRADED A+ |
VERIFIED ANSWERS | LATEST
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COMD 5070 EXAM 1
Why use a band reject filter? ------CORRECT ANSWER---------------To
remove unwanted noise.
(Removing a narrow band doesn't really impact the quality of speech, but
using a wider band reject filter would, because you would be deleting a
number of frequencies that would be important for speech perception)
These were used in the early days of speech analysis because they helped
us understand which frequencies were present in the speech sample, and
they showed the energy at each frequency level (Was the energy in the
lower, middle, or higher part of the frequency range?) This yielded a crude
idea of the ingredients list (frequencies) of a certain sound. ------CORRECT
ANSWER---------------Band-Pass Filter
Using a ___________ filter, you could move from low to high frequencies
as the frequency was being analyzed. (For both types of filter, the
researcher would need to play the sound again and again, looking at a
different frequency each time in order to compare the energy for each.) -----
-CORRECT ANSWER---------------Variable/Adjustable
,The __________ of the components make one sound different from
another - they alter its quality perceptually. ------CORRECT ANSWER--------
-------Relative PROPORTIONS
_______ was a French mathematician and physicist (1768-1830) who
came up with a way of analyzing complex signals and decomposing them
or splitting them into a series of component frequencies. ------CORRECT
ANSWER---------------Joseph FOURIER
All periodic sounds are made of a combination of sine waves (component
frequencies). These individual sine waves may vary by: ------CORRECT
ANSWER---------------Amplitudes
Phase Angles (where they are in the cycle relative to one another)
Frequencies
A ____________ creates a spectrum from a time domain waveform (such
as a microphone signal.) This spectrum shows what the individual
components are. ------CORRECT ANSWER---------------Fourier Transform
(changes the time domain to the frequency domain)
______ Domain Data:
A waveform represents sound directly.
(Air pressure) changes over time.
______ Domain Data:
A line spectrum shows the frequency components of a periodic sound. ------
CORRECT ANSWER---------------Time
Frequency
The human voice is NEARLY periodic. T or F? ------CORRECT ANSWER---
------------True. It has a fundamental and then harmonics which are
,multiples of that fundamental. (But it is NOT truly periodic/perfect in the
scientific sense...its spectrum does not have pure lines, but has peaks and
some spread of energy around the fundamental and harmonics...at the
bases)
_______ is when:
1) All frequencies are present
2) With various different phase relationships to each other
3) with approximately equal amplitude. ------CORRECT ANSWER-------------
--NOISE
The ________ encloses an area that would have been completely filled in
by vertical lines that represent the individual sine waves. It is a
representation of where the tops of all those lines would have been. It
shows us the relative strength of the different frequency components in the
noise. ------CORRECT ANSWER---------------Spectral envelope
What is the FFT Spectrum? What does it show us? What does it show
LESS clearly? Why is it useful? ------CORRECT ANSWER---------------Fast
Fourier Transform
Shows us the range of harmonics that are present in each sound, with a
peak for each of those harmonics.
Formants
Useful for displaying features of the sound SOURCE, not so much about
the vocal tract FILTER.
What is the LPC spectrum? What does it show us? What does it lack? ------
CORRECT ANSWER---------------Linear Predictive Coding
Shows a spectral envelope (with formants).
Doesn't show individual harmonics.
, Tells us more about what the vocal tract FILTER is doing (what its
resonance frequencies are relative to one another), but doesn't give details
of the sound SOURCE.
Spectrum or Spectrogram?
A snapshot in time. Doesn't show progression of a signal over time. ------
CORRECT ANSWER---------------Spectrum
Spectrum or spectrogram?
Shows us individual spectral slices that are arranged side by side over
time. Shows how the frequency components of the signal change over
time. ------CORRECT ANSWER---------------Spectogram
(x-axis is time, y-axis is frequency, darkness indicates intensity)
It is kind of a hybrid domain display (shows both time and frequency).
Shows how the strength in each range of frequencies is changing or
evolving over time.
A wide band spectrographic analysis (300 Hz) gives good ________ detail.
A narrow band spectrogram (45 Hz) tends to blur things together over time,
but gives great ___________ resolution. ------CORRECT ANSWER-----------
----Time/temporal
Frequency
On a 3D spectrogram display, you can have good _________ resolution
OR good ________ resolution, but NOT BOTH. ------CORRECT ANSWER-
--------------Time
Frequency
Wide Band or Narrow Band?
1) Shows individual vertical glottal pulses (vertical striations)
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