MidTerm Summary Flashcards
(146 cards)
1
Q
is one of regular vibration, of one or more definite frequencies. It contains, in addition to a fundamental frequency, higher tones that are harmonics of the fundamental frequency.
A
Musical sound
2
Q
is an alteration in pressure, stress, particle displacement, or particle velocity that is propagated in elastic material.
A
Sound or a sound wave
4
Q
The subjective unit of loudness is the
A
Sone
5
Q
The human ear is sensitive to waves in the frequency range from about, called the audible range.
A
20 to 20,000 Hz
6
Q
is the sensation produced through the ear by the sound wave alterations
A
Sound sensation
7
Q
Types of Ordinary Sound
A
- Speech
- Music or Musical Tone
- Noise
8
Q
is the science of sound including its production, propagation, and effects.
A
Acoustics
8
Q
contains a complex mixture of sounds, some (but not all) of which are in harmonic relation to one another.
A
Speech
9
Q
is sound of irregular vibration, or no definite range of frequencies. It consists of a mixture of many different frequencies within a certain range
A
Noise
10
Q
The ______________ is a measure of the number of waves passing given point in 1 second.
A
frequency of a sound wave
11
Q
that attribute of auditory sensation in terms of which sound may be ordered on a scale primarily related to frequency.
A
Pitch
11
Q
the quality of sound related to its harmonic structure.
A
Timbre
12
Q
is an observer’s auditory impression of the strength of a sound and is associated with the rate at which energy is transmitted to the ear.
A
Loudness
14
Q
The distance between two successive crests of the wave is called the
A
wavelength
15
Q
Intensity also depends on the __________ of the source from the observer.
A
distance
16
Q
Attributes or Characteristics of Sounds
A
Pitch
Timbre
Loudness/Intensity
16
Q
Phon =
A
40 + 10 log2 (Sone)
17
Q
A ______ generates a bright sound and a jagged waveform.
A
violin
18
Q
Sound Power Level (PWL) in dB
From an Isotropic Source in Free Space:
PWL = _________________
A
SPL + 20 log d + 11
19
Q
The__________ produces a mellow, true sound and a relatively curved waveform.
A
flute
20
Q
The maximum distance a wave travels from the normal, or zero, position is the
A
amplitude
23
Q
is the characteristic of sound waves that we perceive as volume.
A
Amplitude
24
Q
A______ makes a pure sound, vibrating regularly in a curving waveform.
A
tuning fork
25
Q
Speed of sound in Various Bulk Materials Materials
Material Speed of Sound (m/s)
Water (0°C) ____________
A
1402
27
The _____ is the number of cycles, or oscillations, a sound wave completes in a given time.
frequency of a sound
28
The product of the wavelength and the frequency must equal the
speed of propagation of the wave
28
Speed of sound in Various Bulk Materials Materials
Material Speed of Sound (m/s)
Air (20°C) ______________
344
28
Speed of sound in Various Bulk Materials Materials
Material Speed of Sound (m/s)
Water (20°C) _________
1482
29
–the root mean square (rms) of the instantaneous sound pressure in a stated frequency band and during specified time interval, unless another time-averaging process is indicated, expressed in N/m2(Pa)
Sound Pressure
30
Speed of Sound in a Solid
V = sqroot (Y/ρ)
31
Speed of Sound in Gases
| V= ______________
V = sqr root of (ˠRT/M)
31
the radiated acoustic power in a stated frequency band expressed in Watts (W).
Sound Power
32
–ten times the common logarithm of the ratio of the sound power to the reference sound power, Wo, (10-12 W) expressed in decibel (dB)
Sound Power Level
34
Sound Power Level (PWL) in dB
From a Source at Ground Level:
PWL = __________________
SPL + 20 log d + 8
35
SPL = _____________
20 log P + 94
36
a delayed return of sound that is perceived by the ear as a discrete sound image.
Echos
37
From Sources with Equal Levels:
| PWLT= ___________
10 log n + PWL
40
Sound Pressure Level (SPL) in dB
From a source at ground level
SPL = ____
PWL –20 log d –8
41
Classes of Microphone Applications
Communication Microphones
Sound Recording & Broadcasting Microphones
General-purpose Microphones
Measurement Microphones
42
–ten times the common logarithm of the square of the ratio of the sound pressure to the reference sound pressure, Po, (20 µPa) expressed in decibel (dB)
Sound Pressure Level
43
Speed of Sound in a Fluid
V = sqroot(B/ρ)
44
–the output impedance of the microphone which determines the amplification methods that are suitable.
Electrical Characteristics
45
Types of Microphone
```
Condenser Microphones
Electret Microphones
Piezoelectric Microphones
Dynamic Microphones
Ribbon Microphones
Carbon Microphones
```
46
–ten times the common logarithm of the ratio of the sound intensity to the reference sound intensity, Io, (10-12 W/m2) expressed in dB.
Sound Intensity Level
47
is the tailing off of sound in an enclosure because of multiple reflections from boundaries.
Reverberation
48
–the average rate of sound energy transmitted in a specified direction through a unit area normal to this direction at the point considered.
Sound Intensity
49
–is concerned with the behavior of sound within an enclosed space with a view to obtaining the optimum effect on the occupants.
Room Acoustics
50
An ______ is a reflected sound wave.
echo
52
SIL = ___________
10 log I + 120
53
This microphone exhibit poor linearity and poor dynamic range but are very rugged. They are poor choice of microphone for high-humidity environments, as the carbon granules coalesce.
Carbon Microphones
54
Properties of Microphones
Electroacoustic Performance
Electrical Characteristics
Sensitivity to External Influences
Cost
55
those intended for high-fidelity reproduction of speech and music.
Sound Recording & Broadcasting Microphones
56
–the ability of the microphone to perform task for which it was designed, generally measured in terms of its sensitivity, directivity, frequency response, transient response, linearity, SNR, and dynamic range.
Electroacoustic Performance
57
–the ability of the microphone to operate independently of the air temperature, relative humidity, and wind speed.
Sensitivity to External Influences
58
is a succession of echoes.
Reverberation
60
We also use the term sound for similar waves with frequencies above (______) and below (________) the range of human hearing.
ultrasonic, infrasonic
60
Sound Pressure Level (SPL) in dB
From an Isotropic Source in free space
SPL = _______
PWL –20 log d -11
60
those intended for speech communication between a small no. of individuals. Examples include telephone microphones & hearing aids
Communication Microphones
60
-those intended for sound reinforcement systems, public address systems, and home use.
General-purpose Microphones
61
Echo and Reverberation Equations
Stephen & Bate Equation
Sabine Equation
Norris-Erying Equation
Fitzroy Equation
61
those intended for laboratory measurement of acoustic pressure. These microphones must be very accurate and highly stable.
Measurement Microphones
63
–in this type of microphone, conversion of acoustic energy to electrical energy occurs because the sound pressure causes small motions of the microphone diaphragm.
Condenser Microphones
64
–these microphones are very similar to the condenser microphone; the main difference is that the externally applied bias voltage is eliminated through the use of a polarized material referred to as an electret.
Electret Microphones
65
–it is a resistive sensor that has been used over the years extensively in situations where it is acceptable to trade a high sensitivity for a poor linearity.
Carbon Microphones
66
these microphones rely on piezoelectric materials for the fundamentally linear conversion of mechanical energy to electrical energy.
Piezoelectric Microphones
66
–moving-coil electrodynamic microphones are the sensor counterpart of conventional electrodynamic loudspeakers.
Dynamic Microphones
69
–are quite similar to moving-coil electrodynamic microphones, but the diaphragm and the coil are replaced by a corrugated ribbon suspended in the gap of the magnetic circuit.
Ribbon Microphones
70
is the time required for the mean square sound pressure of a given frequency in an enclosure, initially in a steady state, to decay after the source is stopped, to 60dB or one-millionth of its initial value.
Reverberation time
70
–a room designed to suppress internal sound reflections as much as possible.
Anechoic chamber
71
–a distortion produced by combining an electrical or acoustical signal with a delayed replica of itself.
Comb Filter Effect
72
In this type of microphone, sound is incident on a diaphragm attached to a plunger that applies a force to carbon granules.
Carbon Microphones
73
–a measure of the efficiency of a surface or material in absorbing sound.
Absorption Coefficient
74
the distortion of a signal detectable by the ear.
Coloration of sound –
75
–the ability of a driver to send the sound waves out in a wide path.
Dispersion
76
–a graph showing the correlation of one signal with another
Correlogram
77
–a room in which the floor, ceiling, and wall are lined with a sound absorbing material to reduce reflections of sound to a minimum. It is also known as anechoic room or free-field room.
Dead Room
78
–also called Precedence Effect. Delayed sounds are integrated by the auditory apparatus if they fall on the ear within 20–40ms of the direct sound.
Haas Effect
79
a loudspeaker designed to reproduce middle-frequency sounds.
Driver
80
–the distortion of a wavefrontcaused by the presence of an obstacle in the sound field.
Diffraction of sound
81
-a proprietary sound-absorbing/ diffusing unit for use in corners of rooms
Korner Killer
82
–a ratio between the sudden drop of sound intensity from its loudest level to its softest level.
Dynamic Range
83
–a divider board used to separate the sound pressure areas in order to reduce the cancellation of sound.
Baffle
84
–a repetitive echo set up by parallel reflecting surfaces.
Flutter echo
85
–the ave.distance traveled between successive reflections
Mean free path
86
–an acoustical treatment plan for rooms in which one end is highly absorbent and the other end reflective and diffusive.
Live end Dead end
87
–the first wavefrontfalling on the ear determines the perceived direction of the sound.
Law of the First Wave front
88
–a delayed return of sound that is perceived by the ear as discrete sound image
Echo
89
–sound generated by air turbulence as it passes through ductwork and air control devices. It increases with an increase in air velocity.
Regenerated sound
90
-a proprietary device for the diffusion of sound through reflection phase-grating means.
Diffusor
91
Total Sound Power Level (PWLT) in dB
From Sources with Unequal Levels:
PWLT= __________
10 log WT+ 120
92
–a loudspeaker type that is used to transform sound energy having a high pressure and low velocity to sound energy having a low pressure and high velocity.
Horn
93
–a plot of frequency vs. sound pressure level in dB on standard NC chart.
Noise Criteria
93
–the interval between two frequencies having a ratio of 2:1.
Octave
95
–a reactive, tuned sound absorber; it is an air cavity within a massive enclosure, connecting to the surroundings by a narrow neck opening.
Helmhotz Resonator
96
–the study of the interaction of the auditory system and acoustics
Psychoacoustics
97
–the bending of sound waves travelling through layered media with different sound velocities.
Refraction of sound
98
TYPES OF SERVICES
1. Aeronautical Fixed Service
2. Aeronautical Mobile Service
3. Aeronautical Mobile-Satellite Service
4. Aeronautical Radio navigation Service
5. Aeronautical Radio navigation-Satellite Service
6. Amateur Service
7. Amateur-Satellite Service
8. Broadcasting Service
9. Broadcasting-Satellite Service
10. Earth Exploration-Satellite Service
11. Fixed Service
12. Fixed-Satellite Service
13. Inter-Satellite Service
14. Land Mobile Service
15. Land Mobile-Satellite Service
16. Maritime Mobile Service
17. Maritime Mobile-Satellite Service
18. Maritime Radio navigation Service
19. Maritime Radion avigation-Satellite Service
20. Meteorological Aids Service
21. Meteorological-Satellite Service
22. Mobile Service
23. Mobile-Satellite Service
24. Port Operations Service
25. Radio Astronomy Service
26. Radio determination Service
27. Radio navigation Service
28. Radio navigation-Satellite Service
29. Safety Service
30. Ship Movement Service
31. Ship Operation Service
32. Space Research Service
33. Special Service
34. Standard Frequency & Time Signal Service
35. Standard Frequency & Time Signal-Satellite Service
99
–the loss of hearing sensation due to the thickening of the eardrum usually at old age.
Presbycosis
100
–is a graph wherein time is plotted in the x-axis, frequency is plotted in the y-axis, and the sound level is indicated roughly by the density of the trace.
Sound spectograph
101
-the maximum sound pressure which the human ear understands without discomfort of pain.
Threshold of Pain
102
–a large loudspeaker that reproduces low audio frequencies at relatively high power level.
Woofer
103
–one of a group of frequencies not necessarily harmonically-related to the fundamental, which appears in complex tones.
Partial
104
–a range of sound measure which the human ear can understand without discomfort or pain or evoke an auditory sensation.
Threshold of tolerance
105
–a high-pitch ringing
Tinnitus
106
–a loudspeaker designed to reproduce high-frequency sounds
Tweeter
107
–a room designed to emphasize reverberations. It is the converse of a dead room.
Reverberation Room
108
TYPES OF STATIONS
1. Aeronautical Station
2. Aeronautical Fixed Station
3. Aircraft Station
4. Amateur Station
5. Base Station
6. Broadcasting Station
7. Coast Station
8. Commercial Receiving Station
9. Experimental Station
10. Fixed Station
11. Land Mobile Station
12. Mobile Station
13. Mobile Portable Station
14. Portable Station
15. Radio Direction-Finding Station
16. Radio Training Station
17. Radio beacon Station
18. Radio location Station
19. Radio navigation Station
20. Radio navigation Land Station
21. Ship Station
22. Standard Frequency & Time Signal Station
23. Transmitting Station
109
–a baffle with two openings at the front in which the back pulsations are bounced back and forth through a maze of small internal boxes.
Labyrinth Baffle
110
Types of Baffles
1.
2.
3.
Bass Reflex
Infinite Baffle
Labyrinth Baffle
111
–a resonance condition in an enclosed space in which sound waves traveling in one direction interact with those traveling in the opposite direction, resulting in a stable condition.
Standing Wave
112
-in this type of baffle, the wave from the back of the diaphragm is isolated from the front wave, except that internal reflections may bounce back through the diaphragm or set-up secondary vibrations of the box itself. It is also known as closed box.
Infinite Baffle
113
-Refers to the airborne transmission of electromagnetic audio signals (radio) or audiovisual signals (television) that are readily accessible to a wide population via standard receivers.
BROADCASTING
113
–a loudspeaker baffle that has an opening dimension below the loudspeaker so that the bass frequencies from the rear emerge to reinforce those radiated directly forward.
Bass Reflex
114
– refers to that period of time between 2100 GMT – 1000 GMT (5:00AM – 6:00PM local standard time).
Daytime
115
– the greatest percentage of modulation that may be obtained by a transmitter without producing in its output harmonics of the modulating frequency in excess of those permitted by these regulation.
Maximum percentage of modulation
116
– refers to that period of time between 1600 GMT – 2100 GMT (12 midnight – 5:00 AM local standard time).
Experimental period
117
– refers to that period of time between 1000 GMT – 2100 GMT (6:00PM – 5:00AM local standard time).
Nighttime
118
– the carrier frequency authorized by NTC.
Authorized Frequency
119
– the effective value of the harmonic voltages present in the audio frequency output of the equipment under test.
Total Harmonic Distortion (THD)
120
– a sinusoidal voltage or current generated in a transmitter and subsequently modulated by a modulating wave.
Carrier wave
121
– the ratio of half the difference between the maximum and minimum amplitude of the AM wave to the average amplitude express in percentage.
Percentage of Modulation
122
– the power that is actually supplied to the radio station
Operating Power
123
– the frequency of the carrier wave.
Carrier Frequency
124
– a station operating on any one channel and is designed to render service over a primary service area which is limited by the subject to such interference as maybe received from a clear channel station.
Secondary Station
125
– the area in which the ground wave field of 3.16 mV/m (70 dBu) is not subject to objectionable interference or objectionable fading.
Primary Service Area
126
– the area receiving service from the ground wave but beyond the primary service area and subject to some interference and fading
Intermittent service area
127
– the area served by the skywave and not subject to objectionable interference. The signal is subject to intermittent variations in intensity.
Service Area
128
– the maximum power at which the transmitter can be operated satisfactorily and is determined by the design of the transmitter.
Maximum Rated Carrier Power
129
– the emission of any frequency outside of the assigned channel or authorized band of frequency and tolerances allowed by these regulations.
Spurious Emission
130
The frequencies are assigned at _______ interval
10 kHz
131
The allocation might be: is indicated by small letters
secondary allocation
132
▪ An entry of the time the station begins to supply power to the antenna and time it stops.
▪ An entry of the time the program begins and ends.
▪ An entry of each interruptions
▪ An entry of the following every 30 minutes: operating constants and antenna current.
Operating Log Entries
133
REGULATING BODIES
| A number of standards bodies work on standards for frequency allocation, including:
▪International Telecommunication Union (ITU)
▪European Conference of Postal and Telecommunications Administrations (CEPT)
▪Inter-American Telecommunication Commission (CITEL)
134
Initially developed Arc Transmitter in 1903
Valdemar Poulsen
135
The allocation might be: is within the responsibility of administrations
exclusive or shared utilization
136
▪ An entry of the time each station identification announcement is made.
▪ An entry briefly describing each program broadcast.
▪ An entry showing that each sponsored program broadcast has been announced as sponsored
▪ An entry showing, for each program of network origin, the name of the network originating the program
Program Log Entries
137
credited as the primary developer of AM technology
Raginald Fessenden
138
The Amplitude Modulated (AM radio) carrier frequencies are in the frequency range of ___________.
535 - 1605 kHz
139
"undamped waves" are now called as
continuous waves
140
AM BROADCAST OPERATING REQUIREMENTS
Operating Schedule
Program Log Entries
Operating Log Entries
141
In what year an American established the first AM station
1924
142
The earliest public radiotelegraph broadcasts were provided as government services, beginning with daily time signals inaugurated on ________, by a number of U.S. Navy stations.
January 1, 1905
143
On _________, Nathan Stubblefield gave a short-range "wireless telephone" demonstration that included simultaneously broadcasting speech and music to seven locations throughout Murray, Kentucky.
January 1, 1902
144
On _________ a London publication, The Electrician, noted that "there are rare cases where, as Dr. Oliver Lodge once expressed it, it might be advantageous to 'shout' the message, spreading it broadcast to receivers in all directions".
October 1898
145
Transmission of radio and television programs from a radio or television station to home receivers by radio waves is referred to as________________ and in most countries requires a broadcasting license.
"over the air" (OTA) or terrestrial broadcasting
146
-a low-frequency flutter
Wow
