Hurry up collection, 100 common sense of acoustics, have you passed?
[Home Theater Network HDAV.com.cn] Sound is everywhere, but it is also very easy to be ignored. Do you know what is acoustic staining? Do you know what binaural effect, Haas effect, Deboe effect, and masking effect mean? Do you know what is the death point of the hall? Know what it is...
These acoustic common senses are not complicated, but are not widely known. Many acoustic practitioners may not be fully aware of it, and many of their friends can't even pass the passing line. I want to have a friend who has "dry goods" in my head. Here, I will learn 100 items of acoustic common sense together with "New Life of Video and Audio".
1. The frequency range that the human ear can hear is 20Hz-20KHz.
2. The device that converts sound energy into electrical energy is a microphone.
3. The device that converts electrical energy into acoustic energy is a loudspeaker.
4, the audio system has a sound feedback whistling, usually to adjust the equalizer.
5, the room reverberation time is too long, there will be sound turbidity.
6, the room reverberation time is too short, there will be sound dry.
7, singing feels too dry, when adjusting the reverberator.
8. The voice is turbid when speaking. The possible reason is that the reverb effect is added.
9. The three elements of sound refer to sound intensity, pitch, and tone.
10. The objective evaluation scale corresponding to the sound intensity is the amplitude.
11. The objective evaluation scale corresponding to pitch is frequency.
12. The objective evaluation scale corresponding to the tone color is the spectrum.
13. The loudness of the human ear is related to the frequency of the acoustic vibration.
14. The relationship between the loudness and frequency of the human ear's perception of high sound pressure level sound is small.
15. The ear is most sensitive to the sound of the mid-range.
16. The human ear feels slower to the sound of high frequency and low frequency band.
17. The relationship between the loudness and frequency of the human ear to the low sound pressure level sound is very large.
18. Each curve in the equal-tone curve shows different sound pressure levels at different frequencies, but the human ear feels the same loudness.
19. In the equal-tone curve, the number marked on each curve indicates the loudness level.
20. The voltage gain formula for the amplifier expressed in decibels is 20 lg (output voltage / input voltage).
21. The unit of the loudness level is phon.
22. The dB value measured by the sound level meter indicates the weighted sound pressure level.
23. The tone is determined by the waveform of the sound being emitted.
24. The time required for the sound signal to drop by 60 dB from the steady state is called the reverberation time.
25. The basic elements of music are melody, rhythm, and harmony.
26. The maximum instantaneous value of the sound wave is called the amplitude.
27. The number of vibrations in one second is called the frequency.
28. If a sound sounds the same as the selected 1KHz pure tone, the sound pressure level of this 1KHz pure tone is defined as the loudness of the sound to be tested.
29, the human ear is most sensitive to the sound of 1-3KHz.
30, the human ear is below 100Hz, the sound of 8K or more Hz is slower.
31. The early reflections on both sides of the stage aggravate and thicken the original sound, which is beneficial to the reflection sound.
32. The reflected sound on the back side of the auditorium acts as an echo to the original sound, which is a harmful reflection.
33. The sound travels in the air at a speed of about 340 m/s.
34. To make the stadium unable to hear two sounds from the main speaker about 34m, a delay of 0.1s should be added to the sound box near the audience.
35. A material with a small reflection coefficient is called a sound absorbing material.
36. A material with a small transmission coefficient is called a sound insulating material.
37. A material with a large transmission coefficient is called a sound-permeable material.
38. The fully sound absorbing material refers to the sound absorption coefficient α=1.
39. The total reflection material refers to the sound absorption coefficient α=0.
40. Rock wool, glass wool and other materials mainly absorb high frequency and medium frequency.
41. Polyurethane sound absorbing foam mainly absorbs high frequency and intermediate frequency.
42. The thin plate plus cavity mainly absorbs low frequency.
43. The thin plate is directly nailed to the wall and the sound absorption effect is very poor.
44, curtain fabric mainly absorbs high and medium frequency.
45, the rough cement wall sound absorption effect is very poor.
46. ​​The human ear can determine the spatial orientation of the sound source through the intensity difference and time difference of the sound source signal, which is called the binaural effect.
47. Two sounds, one after the other, arrive at the human ear for 5-50ms, and the human ear feels that the sound is from the first arrival sound source, called the Haas effect.
48. The left and right sound sources have a sound intensity difference greater than 15 dB. The listener feels that the sound source is a sound source with a strong sound level, called the Deboe effect.
49. The listening threshold of a sound must be improved because of the existence of other sounds. This phenomenon is called the masking effect.
50. Due to the interference of sound in some places in the hall, some frequencies cancel each other out, and the sound pressure level is reduced a lot, called dead point.
51. The sound encounters a concave reflecting surface, causing the sound pressure level of a certain area to be much larger than other areas called sound focusing.
52. The sound is reflected back and forth between two parallel walls in the room to produce a plurality of identical sounds, called vibrating echoes.
54. The room is excited by external sound vibrations to vibrate according to its own natural frequency, called room resonance.
55. There are several overlapping phenomena with the same resonant frequency in the room, which is called the degeneracy of the resonant frequency.
56. The original sound signal spectrum is changed due to degeneracy and the like, and the added timbre is caused to cause distortion, which is called acoustic dyeing.
57. The distance between the point where the direct sound energy density in the sound field is equal to the density of the sound energy of the reverberation and the sound source is called the reverberation radius.
58. When the listening point is within the reverberation halfway, the direct sound plays a major role.
59. The listening sound plays a major role in reverberation when it is outside the reverberation halfway.
60. Sound source vibration causes the air to generate additional alternating pressure, called sound waves.
61. The vibration direction of the particle is perpendicular to the propagation direction of the wave, and is called a transverse wave.
62. The vibration direction of the particle is parallel to the propagation direction of the wave, which is called longitudinal wave.
63. The sound wave radiated by the general point sound source in space belongs to a spherical wave.
64. Sound waves travel in different materials, and the fastest is metal.
65. The slowest speed of sound waves in different materials is air.
66. Sound waves propagate in different materials, and the speed is in the order of metal, wood, water, and air.
67. The echo is generated because the reflected sound is different from the direct sound by more than 50ms.
68. The tremor echo is generated because the sound is reflected back and forth between two parallel walls of light.
69. The sound focus is generated because the sound encounters a concave reflecting surface.
70. Sound diffusion occurs because the sound encounters a convex reflecting surface.
71. In a seat in the auditorium, the speech on the stage is changed into two repeated sounds. The possible reason is that the reflected sound is more than 50ms away from the direct sound.
72. The auditory characteristics of the human ear to different frequencies are most sensitive to the midrange, followed by the high pitch, and the lower the frequency, the less sensitive.
73. The directivity characteristics of sound waves of different frequencies are high directionality and low woofer directivity.
74. The diffracting ability of sound waves of different frequencies is easy to be diffracted by the bass, and the high sound is not easy to be diffracted.
75. The usual way of speaker layout is to hang the high-pitched speaker and adjust the angle; the woofer is close to the ground.
76. The low frequency reverberation of the hall is too long. The more effective measure is to install a thin plate with a cavity on the wall.
77. The best material for sound insulation is double-glazed brick wall with air layer in the middle.
78, 50HZ non-sinusoidal periodic signal, its 4th harmonic is 200Hz.
79. The 3rd harmonic of the 100HZ non-sinusoidal periodic signal is 300Hz.
The 5th harmonic of the 80, 300HZ non-sinusoidal periodic signal is 1500Hz.
The 5th harmonic of the 81, 80HZ non-sinusoidal periodic signal is 400Hz.
82. To make the stadium unable to hear two sounds from the main speaker about 17m, a 50ms delay should be added to the sound box near the audience.
83. The equalizer divides the frequency band by 63, 125, 250, 500, 1K, 2K, 4K, 8K, and 16K, which is 1/1 octave division.
84. The equalizer divides the frequency band by 50, 200, 800, 3.2K, and 12K, and is divided by 4 times.
85. The equalizer divides the frequency band by 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400...20K, which is 1/3 octave division.
86. The best place to choose the best reverberation time is the concert hall.
87. The shortest place to choose the best reverberation time is the multi-track staging studio.
88. The suitable place to adjust the reverberation time is the multi-purpose hall.
89. The Sabin formula is applicable to the calculation of the reverberation time of a room with a small sound absorption coefficient.
90, Ai Run formula is suitable for calculating the reverberation time of various types of rooms.
91. The content of the Sabin formula is: the reverberation time is equal to 0.161X room volume / room surface area X sound absorption coefficient.
92. In order to reduce the degeneracy of the room and avoid sounding, the best length of the room: width: the height ratio is 2:3:5.
93. In the large theater, the seat that is most likely to hear the echo is the front seat.
94. The main way to solve the echoes heard by the audience in front of the large theater is to enhance the sound absorption on the back wall of the auditorium.
95, the correct way to write decibel is dB.
96. The 1 and i in the music notation are one octave apart.
97. The distance between 1 and 2 in the music notation is 1 degree.
98. Sound velocity C, acoustic wave frequency ƒ, acoustic wave wavelength λ, and the relationship between them is C=fxλ.
99. The relationship between the acoustic frequency ƒ and the acoustic period Τ is f=1/T.
100. The condition of standing wave formation is back propagation, the amplitude is the same, the frequency is equal, and the phase difference is 0 or constant.
Let yourself be a primary school student, 100 acoustic common sense, know that 60 are passing, have you passed the exam? Or have you got 100 points? If not, then quickly collect this article! More fresh and fun home theater information Please pay attention to the home theater network (WeChat: cnhifi) http://, the country's most influential home theater audio player interactive media website.
Note: This article is transferred from the new life of audio and video. The article is an independent view of the author and does not represent the position of the home theater network.
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