As we all know, when deploying professional audio, we will all face microphone howling, so how can we avoid this kind of howling interference? Let us start with the best pickup range of the microphone to solve this problem for everyone.
Sound sources have different sound-generating parts, and each microphone has a different pickup range. Can different types of microphones be used to record different characteristics of sound sources perfectly? This is an important topic that audio workers cannot ignore.
Today, there are many types of microphones that are frequently used. The most common types are microphones, condensers, goosenecks, head-mounted and collar clip buttons. They each have their own sound pickup characteristics. It is widely used in different sound pickup occasions.
Vocal mic pickup range
When picking up vocal language programs in the broadcast quotation room, two types of dynamic microphone and condenser microphone are often used. The dynamic microphone is durable, high sensitivity, good directivity, the sound picked up is clear, pure and soft, and the frequency response is in the range of 40 Hz to 16 kHz; the condenser microphone has good sound quality, high sensitivity, and the picked up sound is full, bright, subtle and exquisite , The frequency response is in the audible frequency band of the human ear at 20 Hz-18 kHz. Condenser microphones have good directional characteristics. For example, NeumannU89i microphones have a total of 5 directional characteristics to choose from: omnidirectional, semicircular, cardioid, supercardioid, and figure eight, which can be used in a variety of recording conditions.
The recording in the form of a host of broadcast language programs uses clarity as the main indicator, and most of them use cardioid, supercardioid dynamic microphones or condenser microphones to pick up the sound. The heart-shaped pointing feature is a one-way pickup, only the sound in front of it is picked up. When the angle between the mouth of the vocal and the center axis of the microphone is "0 °", the output frequency response of the microphone is the best. If the speaker sways his face and neck while shaking, and shakes up and down, the mouth deviates from the center axis of the microphone The sound energy will drift or decay. The figure-eight directional microphone is a two-way directional feature, and the sound on the front and back of the microphone can be picked up, which can be used for the pickup of interview programs.
The omnidirectional microphone can be recorded in the range of 360 °. For example, the Neumann U89i microphone has a large pickup area and can be used for pickup occasions with a large number of people. To record broadcast language programs, not only should you be familiar with the directional characteristics of the microphone, but also adjust the distance between the microphone and the sound source. The pickup distance affects the timbre of the sound, and it is also related to the proportional relationship of the reverberation of the direct sound. "Direct mixing ratio" affects the clarity of the sound. In other words, the microphone is too close to the sound source, the low frequency is strengthened, and the sound can not be divided into layers and there is no sense of space. The recording practice proves that: under the good sound collection conditions of balanced room frequency response and uniform sound power distribution, the pitch angle of the microphone, the height of the microphone pole and the distance from the sound source are adjusted repeatedly, and placed within the reverberation radius of the sound field This is the best angle for the microphone to pick up sound, it is also the effective distance for picking up sound, and it also ensures sound clarity and fusion.
It is undeniable that there are many factors that affect the intelligibility of the language, such as the "pop" in the voice. The phenomenon of spraying microphones often exists because the microphone diaphragm is vibrated under the impact of sonic air currents. When the sound of the words is too loud, you will hear a pop. If this happens, you can slightly increase the pickup distance, slightly deviate from the direction of the airflow impact, or turn on the microphone gain attenuation switch to eliminate distortion, reduce gain, and improve sound quality. The problem of too loud and too small vocals also often exists. When two or more sound sources sound at the same time, people will have a different sense of sound in hearing. As far as people's ordinary speech is concerned, everyone has their own characteristics of vocalization, with their own tone, basic tone, harmonic tone, high and low sound, strong and weak, and the sound energy of 20-30 dB when speaking in a low voice, loud The speech is about 60dB, and the voice and audio bandwidth ranges from 60 Hz to 10 kHz. Therefore, the inconsistency in loudness when people are speaking may be a problem with the angle, orientation and pickup distance of the pickup microphone when recording, or it may be a problem with the inconsistency of the quality, characteristics and frequency of the sound source. In the actual recording operation, the use of the mixer and peripheral equipment to adjust the various frequency bands of audio is an important means to ensure audio balance. There are equalizers, compressors, effects, frequency shifters and other hardware peripheral devices in the broadcast quotation room or news live room. This is an important recording method to beautify the voice and ensure the clarity of language programs.
The sound pickup technology of TV audio system is almost the same as the application technology of broadcasting microphone. However, TV audio pickup requires higher sensitivity and directivity of the microphone. At present, most cameras are equipped with two microphones, one of which is above the fuselage, and the microphone follows the camera to rotate, so that the main axis of the microphone pickup always points to the sound picture; the other microphone is used for the sound source around the camera Pickup of the sound. The two microphones configured by the camera generally have super directional characteristics, and the audio picture picked up always appears "simultaneously" with the lens projection in the same pickup direction.
With the development of microphone technology, people have designed various types of microphones, including hand-heldmic, clip-on mic, lavalier mic, and goose-neck mic, to adapt to different Pickup environment. Especially in recent years, the microphone has become more and more concealed, and the gooseneck is getting shorter and shorter. For example, when watching the TV screen of the CCTV news live room, people can hardly see the pickup microphone, and there will be no obstruction to the host ’s face. Scenarios that interfere with the projected picture. The Goose-neck microphone and the gun mic series are the most widely used conference microphones in recent years. These two models have high sensitivity and strong directivity. They can clearly collect the voice of the speaker in front of the microphone, automatically suppress environmental noise and feedback howling, compare Suitable for on-site camera and video conference, interview, TV broadcast and other occasions.
Musical instruments are an indispensable sound source factor in music performance. The sound characteristics of the sound source are extremely complex, but the sound components are nothing more than strings, membranes, springs, rods and air columns. From the point of view of the structure of a single sound source, the piano has a wide range of sound, crisp treble, full midrange, thick bass and rich timbre. Two microphones can be selected, one in the treble string area and one in the bass string area. At a distance of about 30 cm, the quasi-strings will pick up crisp and full sound. The violin pulls the pony tail to wipe the string, and the sound is beautiful and shiny. You can choose an omnidirectional microphone to pick it up above the bridge; the recorded sound is soft and elegant; the cello has a rich tone, like a bass bass, and the pickup part is also above the bridge; Wind instruments such as wooden tubes belong to the air column vibration sound. You can choose a heart-shaped dynamic coil microphone placed at a position close to 40 cm in the tube hole to obtain a soft and bright sound effect; the brass instrument trumpet, trombone and French horn sound bright, The vocal part is at the horn mouth, when using the microphone, you should pay attention to the direction of the sound wave flow slightly deviated from the horn mouth, suitable for collection in the sound source area beyond 50cm. If a condenser microphone is used for sound pickup, it can be attenuated by 10 dB, and a good sound pickup effect may be achieved. The drum kit is a more commonly used kit instrument during the performance of the program. Both the Tongtong drum and the bass drum can be picked up with a heart-shaped dynamic coil microphone. The microphone is at an angle of 45 ° to the drum surface, and the microphone is placed 30 cm above the drum surface. Dynamic response. Picking up the sounds of hi-hat and standing cymbals, it is better to choose a cardioid condenser microphone. The microphone picks up the sound of the front of the cymbals in one direction. It sounds crisp and sharp, the rhythm is bright, and the tone is rich.
Pick up the live performance of a large concert, the scene is magnificent, and more microphones are used. Generally, the main microphone pickup method is adopted. The NeumannSM69 microphone has a large pickup area, and can use X / Y and ORTf to pick up the sound field reverb. Auxiliary microphones can be selected from U87 and U89, which are respectively placed in the best pickup position in the middle of string instrument group, woodwind instrument group, brass instrument group and percussion instrument group. The dynamic range of brass instruments and percussion instruments is large, and the dynamic sound can also be obtained by using dynamic microphones.
When using multiple microphones to pick up sounds, the auxiliary microphone cannot be divided equally with the main microphone. The auxiliary microphone's pickup volume should be less than the main microphone, otherwise it will affect the entire sound field effect. The microphone settings should be fine. The vocals and instruments should be carefully arranged in the pickup position of the entire band. The pickup height, angle and pickup distance of each microphone should be carefully adjusted. To be adjusted. The ratio of microphone to vocals and music is also one of the important adjustments. If the singer accounts for 60% of the entire performance sound field, the instrument sound field can only account for 40% of the loudness. According to the characteristics of the orchestration and the change of melody, singing and music sound field Modulation according to the ratio of 5: 5 is also possible. During the normal performance, the microphone and line adjustments are basically in place, and you can obtain a state in which the vocal level is natural and orderly, and the sound image layout of the band seats is reasonable.
The recording is learned, and the use of microphones is more demanding. You must carefully interpret, understand, and calm down to taste carefully. No matter how high the digital equipment index is, it needs to be carefully adjusted; no matter how good the sound source is, there are artificial factors. Only by complementing resources, using it, combing left and right, and taking advantage of each, can we record the natural and harmonious sound and obtain Perfect recording effect!
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