Are you satisfied with the sound in your car?
Do you think that the original car's sound is not layered, the sound field is narrow, and the voice is not full?
Even if you have upgraded the sound once, still feel that the high frequency is not bright enough, and the low frequency is not enough?
Do you think that the original car's audio listening song is not as good as listening to the radio?
If you have one of the above questions, you may need to upgrade the sound in your car. If you don't know how to modify the car stereo, then you can pay attention to us. Now every Monday, Wednesday and Friday, very urban cars will bring you special courses - car audio modification from entry to mastery, only need to spend each lesson Read in a few minutes and easily learn if you modify the car stereo!
First, the acoustic knowledge is divided into three parts (1) The sound is the vibration of air molecules. The vibration of the object (we call it "sound source") causes the corresponding vibration of the air molecules, which is transmitted to the human ear and causes the tympanic membrane to vibrate. Through the joint action of a series of auditory organs such as the middle ear and the inner ear, the sound is heard. Not all vibrations of air molecules form sound, and the vibration of air molecules has a certain regularity. We describe it as "wave". Below we make a simple explanation of "sound wave":
(2) Sonic waves throw stones into the calm water surface, which will form a group of water waves that spread to the surrounding. This is a relatively intuitive "wave" that we can see. The sound waves formed by the vibration of air molecules are more complicated. A group of dense waves that are diffused into the surrounding area. The air molecules do not run from the sound source to your ear, but vibrate in its original position, causing the air molecules adjacent to it to vibrate. This is how the sound propagates quickly from the sound source, and the speed of the sound in the air is 331 m / sec.
As a simple example, the movement of the wheat wave is very similar to that of the sound wave. The direction of vibration of the particle is parallel to the direction of motion of the wave. The wave needs to be transmitted through the medium, and the movement of the wheat wave naturally stops at the edge of the field. The medium of sound wave propagation is air molecules, so the sound cannot be transmitted in the vacuum.
(3) Frequency of sound The frequency of sound waves per second is called frequency, and the frequency is called sound wave between 20Hz and 20KHz;
Frequency greater than 20KHz is called ultrasonic wave;
A frequency less than 20 Hz is called an infrasound wave.
Ultrasonic and infrasound waves are inaudible, and seismic waves and tsunamis are secondary sound waves. Some animals have much more sensitive ears than humans, such as bats that can "hear" ultrasound.
There are very few "pure sounds" of a single frequency in the world. The sounds we hear are mostly composite sounds of various frequencies. For example, the single tone of a musical instrument is a periodic composite sound, and the voice is a non-periodic composite sound.
Let us have a more intuitive concept of the frequency of sound:
The "bucket" sound frequency of the drum is very low, about tens of hertz;
The human voice frequency range is mainly between 200 Hz and 4000 Hz;
The frequency of buzzing and ringing is about 2000 Hz to 3000 Hz;
In human speech, female voice is higher than male voice; child voice is higher than adult frequency; "ah" sound frequency is lower, "咿咿" sound frequency is slightly higher, "嗤嗤, 嘶嘶" sound frequency is the highest. It is useful to know this. In actual matching, you can often test the response of the patient to the frequency of the sound before and after wearing the hearing aid.
Second, the basic properties of sound (a) the propagation characteristics of sound waves Sound waves will produce reflection, refraction, diffraction and interference in the propagation:
(1) Reflection and refraction. When sound waves enter the interface of another medium, the reflection phenomenon occurs. When an obstacle is encountered, a part of the sound wave will enter the obstacle and cause refraction.
(2) Diffraction, when the sound wave encounters a wall or other obstacle, a part of the sound wave bypasses the edge of the obstacle and continues to propagate forward. This phenomenon is called diffraction.
(3) Interference, interference refers to the phenomenon that some sound waves with the same frequency superimpose each other in the propagation, which will make the sound wave strengthen in some places and weaken in some places.
In addition to the above three main characteristics, sound waves also have absorption and transmission phenomena, resonance phenomena, and attenuation phenomena during the propagation process.
(2) The three-element sound of the sound mainly expresses its characteristics through three elements: volume, pitch and tone.
(a) Volume, also known as loudness, refers to the subjective feeling of the human ear on the strength of the sound. The volume is mainly determined by the amplitude of the sound wave.
(b) The pitch, also known as pitch, refers to the subjective feeling of the human ear on the tone of the tone. The pitch is mainly determined by the frequency of the sound wave.
(c) Tone is the subjective feeling of the human ear on the characteristics of the sound. The tone depends primarily on the spectral structure of the sound.
The three elements of the sound can be heard the intensity and frequency range of the sound. The basic characteristics of the human ear hearing. (1) The human ear hearing range can be heard, the hearing threshold and the pain field determine the hearing range of the human ear.
(1) audible sound: refers to the sound that normal people can hear, the frequency range is 20 Hz ~ 20 kHz, called audio.
(2) Hearing threshold: The audible sound must reach a certain intensity to be heard, and the intensity range that normal people can hear is 0-140 dB. The lowest sound pressure level that makes the sound audible is called the hearing threshold, which is related to the frequency of the sound. In a good listening environment, the hearing threshold of young people with normal hearing is very close to zero decibels in the frequency range of 800 to 5000 Hz (the corresponding sound pressure value of sound waves is 0.00012 Pa).
(3) Pain area: The sound pressure level that makes the ear feel pain is called the pain field, and it has little relationship with the frequency of the sound. When the sound pressure level reaches 120 dB, the human ear feels uncomfortable; when the sound pressure level is greater than 140 dB, the human ear feels pain; when the sound pressure level exceeds 150 dB, the human ear may experience acute damage.
(2) Hearing characteristics The auditory characteristics of the auditory response are the basic characteristics that reflect the loudness perception of pure tones of different frequencies, and are usually expressed by equal-curve curves.
(1) The human ear is most sensitive to the acoustic sound in the frequency range of 3 to 4 kHz. The sensitivity of the human ear to low frequency and high frequency sounds is reduced.
(2) The higher the sound pressure level, the more the equal-tone curve tends to be flat, the sound pressure level is different, and the equal-tone curve has a large difference, especially in the low frequency band. Therefore, when playing, especially when playing at a small volume, it is necessary to wait for the control circuit to compensate.
(III) Auditory Threshold Characteristics The auditory threshold characteristic refers to the characteristic that the human ear has different auditory sensitivities to sounds of different frequencies. Normally, the sound intensity that a normal person can hear ranges from 0 to 140 dB. The hearing threshold of the human ear in the frequency range of 800 Hz to 5 kHz is very close to 0 dB, while the hearing sensitivity to signals below 100 Hz or signals above 18 kHz is greatly reduced.
(4) Auditory masking characteristics The auditory masking characteristic means that a strong sound tends to cover a weaker sound, so that weaker sounds cannot be heard. This masking feature has frequency domain masking and time domain masking.
(1) Frequency domain masking. It means that a large amplitude frequency signal will mask a relatively small amplitude frequency signal at an adjacent frequency, so that the small signal cannot be inaudible.
(2) Time domain masking. It means that in time, a strong signal will mask the weaker sounds for a period of time before and after, so that they cannot be heard.
8P8C (RJ-45) modular jacks (computer networking)
F connector (TV antenna/cable/satellite)
Do you think that the original car's sound is not layered, the sound field is narrow, and the voice is not full?
Even if you have upgraded the sound once, still feel that the high frequency is not bright enough, and the low frequency is not enough?
Do you think that the original car's audio listening song is not as good as listening to the radio?
If you have one of the above questions, you may need to upgrade the sound in your car. If you don't know how to modify the car stereo, then you can pay attention to us. Now every Monday, Wednesday and Friday, very urban cars will bring you special courses - car audio modification from entry to mastery, only need to spend each lesson Read in a few minutes and easily learn if you modify the car stereo!
First, the acoustic knowledge is divided into three parts (1) The sound is the vibration of air molecules. The vibration of the object (we call it "sound source") causes the corresponding vibration of the air molecules, which is transmitted to the human ear and causes the tympanic membrane to vibrate. Through the joint action of a series of auditory organs such as the middle ear and the inner ear, the sound is heard. Not all vibrations of air molecules form sound, and the vibration of air molecules has a certain regularity. We describe it as "wave". Below we make a simple explanation of "sound wave":
(2) Sonic waves throw stones into the calm water surface, which will form a group of water waves that spread to the surrounding. This is a relatively intuitive "wave" that we can see. The sound waves formed by the vibration of air molecules are more complicated. A group of dense waves that are diffused into the surrounding area. The air molecules do not run from the sound source to your ear, but vibrate in its original position, causing the air molecules adjacent to it to vibrate. This is how the sound propagates quickly from the sound source, and the speed of the sound in the air is 331 m / sec.
As a simple example, the movement of the wheat wave is very similar to that of the sound wave. The direction of vibration of the particle is parallel to the direction of motion of the wave. The wave needs to be transmitted through the medium, and the movement of the wheat wave naturally stops at the edge of the field. The medium of sound wave propagation is air molecules, so the sound cannot be transmitted in the vacuum.
(3) Frequency of sound The frequency of sound waves per second is called frequency, and the frequency is called sound wave between 20Hz and 20KHz;
Frequency greater than 20KHz is called ultrasonic wave;
A frequency less than 20 Hz is called an infrasound wave.
Ultrasonic and infrasound waves are inaudible, and seismic waves and tsunamis are secondary sound waves. Some animals have much more sensitive ears than humans, such as bats that can "hear" ultrasound.
There are very few "pure sounds" of a single frequency in the world. The sounds we hear are mostly composite sounds of various frequencies. For example, the single tone of a musical instrument is a periodic composite sound, and the voice is a non-periodic composite sound.
Let us have a more intuitive concept of the frequency of sound:
The "bucket" sound frequency of the drum is very low, about tens of hertz;
The human voice frequency range is mainly between 200 Hz and 4000 Hz;
The frequency of buzzing and ringing is about 2000 Hz to 3000 Hz;
In human speech, female voice is higher than male voice; child voice is higher than adult frequency; "ah" sound frequency is lower, "咿咿" sound frequency is slightly higher, "嗤嗤, 嘶嘶" sound frequency is the highest. It is useful to know this. In actual matching, you can often test the response of the patient to the frequency of the sound before and after wearing the hearing aid.
Second, the basic properties of sound (a) the propagation characteristics of sound waves Sound waves will produce reflection, refraction, diffraction and interference in the propagation:
(1) Reflection and refraction. When sound waves enter the interface of another medium, the reflection phenomenon occurs. When an obstacle is encountered, a part of the sound wave will enter the obstacle and cause refraction.
(2) Diffraction, when the sound wave encounters a wall or other obstacle, a part of the sound wave bypasses the edge of the obstacle and continues to propagate forward. This phenomenon is called diffraction.
(3) Interference, interference refers to the phenomenon that some sound waves with the same frequency superimpose each other in the propagation, which will make the sound wave strengthen in some places and weaken in some places.
In addition to the above three main characteristics, sound waves also have absorption and transmission phenomena, resonance phenomena, and attenuation phenomena during the propagation process.
(2) The three-element sound of the sound mainly expresses its characteristics through three elements: volume, pitch and tone.
(a) Volume, also known as loudness, refers to the subjective feeling of the human ear on the strength of the sound. The volume is mainly determined by the amplitude of the sound wave.
(b) The pitch, also known as pitch, refers to the subjective feeling of the human ear on the tone of the tone. The pitch is mainly determined by the frequency of the sound wave.
(c) Tone is the subjective feeling of the human ear on the characteristics of the sound. The tone depends primarily on the spectral structure of the sound.
The three elements of the sound can be heard the intensity and frequency range of the sound. The basic characteristics of the human ear hearing. (1) The human ear hearing range can be heard, the hearing threshold and the pain field determine the hearing range of the human ear.
(1) audible sound: refers to the sound that normal people can hear, the frequency range is 20 Hz ~ 20 kHz, called audio.
(2) Hearing threshold: The audible sound must reach a certain intensity to be heard, and the intensity range that normal people can hear is 0-140 dB. The lowest sound pressure level that makes the sound audible is called the hearing threshold, which is related to the frequency of the sound. In a good listening environment, the hearing threshold of young people with normal hearing is very close to zero decibels in the frequency range of 800 to 5000 Hz (the corresponding sound pressure value of sound waves is 0.00012 Pa).
(3) Pain area: The sound pressure level that makes the ear feel pain is called the pain field, and it has little relationship with the frequency of the sound. When the sound pressure level reaches 120 dB, the human ear feels uncomfortable; when the sound pressure level is greater than 140 dB, the human ear feels pain; when the sound pressure level exceeds 150 dB, the human ear may experience acute damage.
(2) Hearing characteristics The auditory characteristics of the auditory response are the basic characteristics that reflect the loudness perception of pure tones of different frequencies, and are usually expressed by equal-curve curves.
(1) The human ear is most sensitive to the acoustic sound in the frequency range of 3 to 4 kHz. The sensitivity of the human ear to low frequency and high frequency sounds is reduced.
(2) The higher the sound pressure level, the more the equal-tone curve tends to be flat, the sound pressure level is different, and the equal-tone curve has a large difference, especially in the low frequency band. Therefore, when playing, especially when playing at a small volume, it is necessary to wait for the control circuit to compensate.
(III) Auditory Threshold Characteristics The auditory threshold characteristic refers to the characteristic that the human ear has different auditory sensitivities to sounds of different frequencies. Normally, the sound intensity that a normal person can hear ranges from 0 to 140 dB. The hearing threshold of the human ear in the frequency range of 800 Hz to 5 kHz is very close to 0 dB, while the hearing sensitivity to signals below 100 Hz or signals above 18 kHz is greatly reduced.
(4) Auditory masking characteristics The auditory masking characteristic means that a strong sound tends to cover a weaker sound, so that weaker sounds cannot be heard. This masking feature has frequency domain masking and time domain masking.
(1) Frequency domain masking. It means that a large amplitude frequency signal will mask a relatively small amplitude frequency signal at an adjacent frequency, so that the small signal cannot be inaudible.
(2) Time domain masking. It means that in time, a strong signal will mask the weaker sounds for a period of time before and after, so that they cannot be heard.
A keystone jack is a standardized snap-in package for mounting a variety of low-voltage electrical jacks or optical connectors into a keystone wall plate, face plate, surface-mount box, or a patch panel.
Many types of jacks are available in the keystone module format, limited mainly by their physical size, including:
8P8C (RJ-45) modular jacks (computer networking)
F connector (TV antenna/cable/satellite)
RCA jacks (audio/video)
4-pin mini-DIN (S-Video jacks)
HDMI jacks (high-definition video and audio)
Optical fiber connectors
BNC connector
4-pin mini-DIN (S-Video jacks)
HDMI jacks (high-definition video and audio)
Optical fiber connectors
BNC connector
With compact size, integral shutter, keystone mounting format a, our keystone Jack for voice and Category 5e and 6A ensure a smart, reliable installation. All copper conductors are plated with gold. The 8 pins of RJ45 tool-less keystone jack are effortlessly terminated in one simple operation resulting in reliable interconnection in record time. The jacks can be reused several times if a wiring mistake is made.
What's more,we can also supply you blank patch panel, face plate and surface mount box to use together with our modular jacks.
Keystone Jack, Cat6 Keystone Jack, Cat5e Keystone Jack, Rj45 Keystone Jack, Australian Keystone Jack
NINGBO YULIANG TELECOM MUNICATIONS EQUIPMENT CO.,LTD. , https://www.yltelecom.com