Sound sources have different sounding parts, and each microphone has a different pickup range. Can different types of microphones be used to perfectly record different characteristics of sound sources? This is an important topic that audio workers cannot ignore.
Today, there are many types of microphones that are often used. The most common ones are dynamic, condenser, gooseneck, head-mounted, and lavalier button styles. They each have their own pickup characteristics. It is widely used in different pickup situations.
When picking up vocal language programs in the broadcast quotation room, two types of dynamic microphones and condenser microphones are often used. The dynamic microphone is sturdy and durable, with high sensitivity, good directivity, and the picked up sound is clear, pure and soft, and the frequency response is in the range of 40 Hz～16 kHz; the condenser microphone has good sound quality, high sensitivity, and the picked up sound is full, bright, subtle and delicate , The frequency response is in the audible frequency band of 20 Hz-18 kHz. Condenser microphones have good directional characteristics. For example, the Neumann U89i microphone has 5 directional characteristics to choose from: omnidirectional, semicircular, cardioid, supercardioid and figure-8, which can be used in a variety of recording conditions.
In the form of broadcast language program host, the main indicator is clarity, and most of them use cardioid, super-cardioid dynamic microphones or condenser microphones to pick up the sound. The cardioid pointing characteristic is one-way pickup, only picking up the sound directly in front. When the vocal mouth is aligned with the central axis of the microphone at an angle of "0°", the output frequency response of the microphone is the best. If the speaker is speaking, the face and neck are swaying from side to side, shaking up and down, and the mouth deviates from the central axis of the microphone. The sound energy will drift or decay. The figure-of-eight directional microphone has a two-way directional characteristic, and the sound on the front and back of the microphone can be picked up, and it can be used for the pickup of interview programs.
The omnidirectional microphone can record the sound in the range of 360°, such as the Neumann U89i microphone, which has a large pickup area and can be used for pickup occasions with a large number of people.
To record broadcast language programs, you must not only 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 sound of the direct sound. The "direct mixing ratio" affects the clarity of the sound. That is to say, the microphone is too close to the sound source, the low frequency is strengthened, and the sound is indistinguishable, and there is no sense of space; the microphone and the sound source are too far away, the vocal clarity is poor, the sound is faint, the direct sound is weakened, and the intelligibility is poor. Recording practice has proved that under the condition of good sound pickup with balanced indoor frequency response and uniform sound power distribution, repeatedly adjust the pitch angle of the microphone, the height of the microphone pole and the distance from the sound source, and place it within the reverberation radius of the sound field , This is the best angle for the microphone to pick up the sound, it is also the effective distance for picking up the sound, and it also ensures the clarity and fusion of the sound.
It is undeniable that there are many factors that affect the intelligibility of speech, such as the "poof" sound in speech. The phenomenon of microphone spraying often exists, because the microphone diaphragm is vibrated under the impact of sound wave airflow. When the voice is too loud, a popping sound will be heard. If this happens, you can slightly increase the pickup distance, slightly deviate from the direction of the impact of the airflow, or turn on the microphone gain attenuation switch, so as to eliminate distortion, reduce gain, and improve sound quality. The problem of excessively loud or small human voices also often exists. When two or more sound sources sound at the same time, people will have a sense of different sound levels. As far as people’s ordinary speech is concerned, everyone has their own vocal characteristics, with their own tone, with fundamental, homophonic, high and low, strong and weak, and the energy of speaking in a low voice is 20-30 dB, loudly The speech is about 60dB, and the voice audio bandwidth is in the range of 60 Hz-10 kHz. Therefore, the inconsistency of loudness when people speak may be caused by the angle, orientation, and distance of the microphone during recording, or the quality, characteristics, and audio frequency of the sound source are inconsistent. In the actual recording operation, the use of the mixer and peripheral equipment to adjust each frequency band of the audio frequency is an important means to ensure the sound frequency balance. There are hardware peripherals such as equalizers, compressors, effectors, frequency shifters, etc. in the broadcast quotation room or live news room. This is an important recording method for beautifying people's voice and ensuring the clarity of language programs.
The sound pickup of a TV audio system is roughly the same as the application technology of a broadcasting microphone. However, TV audio pickup requires a higher sensitivity and directivity index of the microphone.
At present, most cameras are equipped with two microphones, one of which is on the top of the body, the microphone follows the camera rotation, so that the direction of the main axis of the microphone pickup always points to the audio screen; the other microphone is used for the sound source around the camera The sound of the pickup. The two microphones of the camera configuration generally have super strong directional characteristics, and the audio picture picked up always appears "simultaneously" in the same pickup direction as the lens projection.
With the development of microphone technology, people have designed various types of microphones, including hand-held mic, clip-on mic, lavalier mic, and goose-neck mic to adapt to different types of microphones. Sound pickup environment. Especially in recent years, the microphone has become more and more concealed, and the gooseneck has become shorter and shorter. For example, when watching the TV screen of the CCTV news broadcast room, people can hardly see the pickup microphone, and there will be no obstruction of the host’s face. A scene that interferes with the projection screen. The Goose-neck microphone and gun mic series are the most widely used conference microphones in recent years. These two styles have high sensitivity and strong directivity. They can clearly collect the voice of the speaker in front of the microphone and automatically suppress environmental noise and feedback howling. Suitable for on-site photography and video conferences, interviews, TV broadcasts and other occasions.
In summary, recording is knowledgeable and the use of microphones is exquisite. It must be carefully interpreted, comprehend, and tasted carefully. No matter how high the index of digital equipment is, it needs to be carefully tuned; no matter how good the sound source is, there are also human factors. Only when resources are complementary, used for it, combed left and right, and each has their own strengths, can they record natural and harmonious sounds and reproduce familiar sounds. , Pleasing and beautiful sound effects.