Chapter 10 Flashcards
Please choose the best description of a wave pulse that propagates from left to right and is reflected from a fixed boundary.
The displacement remains zero and the reflected wave changes its polarity (undergoes a 180 degree phase change).
Two sinusoidal waves having the same frequency (and wavelength), the same amplitude and are 180 degrees out of phase are traveling in opposite directions. When the two waves are out-of-phase with each other they cancel, and when they are exactly in-phase with each other they add together. Which of the following best describes the combined wave?
A standing wave
The node is a point in a wave where amplitude is ____ .
zero
When a mass-spring system is Driven Below Resonance, the displacement of the mass will be (choose from below):
in phase with force
If you are looking at the resonance plot of a system, and you look at the frequencies below resonance, this region of the plot is said to be ____ because ____ determines the value of displacement.
stiffness-controlled
stiffness
When a wave pulse is reflected from a soft (open) boundary, particle displacement reflects ____ , velocity reflects ____ , and pressure reflects ____ .
in phase
in phase
out of phase
For a tube closed at one end and open at the other, when driven at a resonant frequency, pressure at the closed end is best represented by ____ and pressure at the open end is best represented by ____ .
an anti-node
a node
As a wave propagate, it loses energy over time, and so it experiences a reduction in amplitude of both its position and velocity. This process is called ______.
damping
A resonant cavity can behave like a filter.
True
At the open of a resonator there is a mismatch between the rapidly moving molecules inside the resonator and the relatively slower-moving air molecules outside the resonator. What is this called?
Impedance mismatch
A resonator like the vocal tract is a passive acoustic filter.
True
The ear canal can be approximated by an:
open-closed tube
Resonant frequencies in the vocal tract have their own term, which is __________.
formants
If F1 = 500 Hz, what was the length in centimeters of the vocal tract? Assume that sound travels at 340 m/s. (enter a number only)
17
Suppose you have a vocal tract 10 cm in length that can be approximated with the equation below. What is the frequency of the first resonant mode in Hz? Assume that sound travels at 344 m/s.
f= c* (2n-1) / (4*length)
860
What is the second resonant frequency in Hz of a 4 cm pipe closed at one end and open at the other? Round your answer to the nearest integer. Assume sound travels at 344 m/s.
Choose from one of the following two equations:
f = c* (2n-1) / (4*Length)
f = c* (n) / (2*Length)
6,450
The resonant frequencies are those frequencies having wavelengths equal to f = c* (2n-1) / (4*Length). Assume sound travels at 344 m/s. What is the third resonant frequency in Hz of a 11 cm tube closed at one end and open at the other? Round your answer to the nearest integer.
3,909
Suppose you have a vocal tract 14.6 cm in length. What is the frequency of the third resonant mode in Hz? Round your answer to the nearest integer. Assume that sound travels at 344 m/s.
f = c* (2n-1) / (4*L)
2,945
If the second formant = 2,026 Hz, what is the length of the vocal tract in cm? Round your answer to 2 decimal places. Assume that sound travels at 344 m/s.
L = c(2n-1) / (4f)
12.73
For a pipe closed at one end and open at the other, when driven at a resonant frequency, pressure at the closed end is best represented by
____ and pressure at the open end is best represented by ____.
an anti-node
a node
