What Should I Consider When Buying an Audio Recording Program?

The recording studio is a special room for recording or broadcasting of systems such as radio, television, film, record, and audio-visual education. It is the most demanding type of building in terms of indoor acoustics. The design process is the same as that of the hall.

Studio sound quality design

The recording studio is a special room for recording or broadcasting of systems such as radio, television, film, record, and audio-visual education. It is the most demanding type of building in terms of indoor acoustics. The design process is the same as that of the hall. However, the reverberation time of the recording studio is slightly shorter than that of the hall, and the frequency characteristics are more stringent. In order to meet the needs of different programs, the reverberation time and frequency characteristics of the recording studio can be adjusted appropriately. The recording studio's noise tolerance standards are extremely strict. In terms of sound quality design and noise control, there are special requirements for the recording studio.
The design content includes the choice of recording room volume and size ratio; the choice of reverberation time and its frequency characteristics; the selection and arrangement of sound-absorbing materials and structures. The sound quality design of the recording studio should meet the requirements of different nature programs and different performance scales.
Volume and size ratio In the design, the volume and size ratio of the recording studio should be determined according to the nature and scale of the program. If a large band is recording in a small recording studio, the loudness will be too loud, which will cause the player and conductor to lose their sense of direction, leading to an imbalance in the sound of various instruments. Language recording studios usually record for 1 or 2 people, and their volume should not be very large. However, the small room has few normal vibration modes, the distribution is not uniform enough, and low frequency is prone to hum. According to experience, the relationship between the number and volume of various recording studios is shown in Table 1. For multi-channel recording, since each channel is recorded under the conditions of short reverberation and sound isolation, the recording room volume can be appropriately reduced.

In order to prevent sound quality defects such as sound focusing and trembling echoes, and to facilitate the arrangement of bands and microphones, the recording studio is generally used in irregular shapes such as rectangular, trapezoidal or non-parallel walls, inclined roofs, etc. Avoid using arches or concave surfaces. See Table 2 for commonly used size ratios.

In addition to the size ratio of Table 2 in the language recording studio, in order to make the normal vibration mode evenly distributed and eliminate hum, other ratio sizes can also be selected. The interval of normal vibration frequency is relatively uniform. Designing the recording studio into an irregular shape is effective for evenly distributing normal vibration frequencies and eliminating hum. The length, width and height of the music recording studio should be considered from the arrangement of the band. The volume and size of the TV studio should be determined according to the requirements of the TV process.
Reverberation time and its frequency characteristics People do not directly listen to the recording of the program in the studio, but send it through the playback system, and listen in a room with reverberation, so for similar programs, the reverberation time of the recording studio The hall is slightly shorter. To ensure that the recording studio meets the sound quality requirements, the best reverberation time and its frequency characteristics must be selected according to its purpose and volume:
The reverberation time of language recording studios in many countries use a straight frequency characteristic curve in the range of 125 to 4000 Hz, about 0.3 seconds. In China, a frequency characteristic curve in the range of 100 to 4000 Hz with an increase of 0.3 to 0.4 seconds is often used, or a flat frequency characteristic curve of 0.4 seconds is used. Properly increasing the absorption of the low frequency and shortening its reverberation time can reduce or eliminate the hum of the recording studio.
The music recording studio should choose the best reverberation time and frequency characteristics according to different contents. Experience shows that when recording classical music, you must use mono or stereo two-channel recording in the natural reverberation recording room to obtain beautiful sound quality. When recording modern music, a multi-channel recording method should be used to adjust the volume and sound quality of the split; add split reverb time and split recording to facilitate post-processing. In order to ensure that each channel is adjusted as described above without affecting other channels, the reverberation time of the recording studio must be short, and screen isolation is also required. For strong sound or weak music instruments, such as percussion instruments and pianos, in order to meet the requirements of sound insulation, you can record in small recording rooms with strong sound insulation and short reverberation time. The frequency characteristics of these instruments should be as straight as possible, because shortening the low frequency reverberation time is necessary to ensure the low frequency isolation. In order to meet the above two types of recording technology requirements, two recording rooms with different sound quality conditions can be designed; a recording room can also be designed, but the characteristics of the indoor sound absorption structure must be able to be changed, and the reverberation time and frequency characteristics must be larger. Adjustment of the amplitude. Music recording control room, audition room, etc. must adjust or evaluate the sound quality of the recording according to the monitored sound quality. Its reverberation time can be in the range of 63 ~ 6300 Hz, and a flat frequency characteristic curve of about 0.3 seconds is used.
The microphones of TV studios (including those used to broadcast arts and television programs) are far away from the performers, indoor background noise is high, and various work and living environments are often simulated. Therefore, shorter ones are often used. Reverberation time.
The relationship between volume and reverberation time recommended by the British BBC and Japanese NHK is shown in the figure, and China's approach is close to the recommended value of Japanese NHK.

Sound-absorbing materials, sound-absorbing structures and arrangements In order to obtain the above-mentioned various reverberation times and their frequency characteristics, the recording studio can be designed with various sound-absorbing materials and structures, including porous materials with different cavities, different thicknesses and bulk densities Plate resonator made of materials and various plates, perforated plate or slotted plate structure of different specifications. For TV studios, because there are many indoor lighting electrical equipment and layout props, fire-resistant sound-absorbing materials and structures must be selected, such as inorganic porous materials installed on metal keels. In order to obtain the best reverberation time and frequency characteristics of recording studios, various resonance sound absorption structures with large sound absorption coefficients in the low frequency band and materials and structures with large sound absorption coefficients in the middle and high frequency bands are often used in combination. For recording studios with short reverberation and strong absorption, full-band absorption structures are commonly used, such as porous materials or composite structures with large cavities.
When recording in a recording room, the positions of the sound source and microphone are not fixed, so the sound field distribution needs to be more uniform than the hall, in order to arrange the band and microphone. For this reason, it is necessary to arrange the absorption surfaces and reflection surfaces staggered, and the low-frequency sound absorption structure and the middle and high frequency sound absorption materials. The acoustic coefficients are approximately equal. At the same time, some diffusers can be installed on the wall or ceiling. Diffusion bodies are often made of materials with small sound absorption coefficients, such as square cylinders, triangular cylinders, and cylinders. When the size of the diffuser is equivalent to the wavelength, it has a good diffusion effect in this frequency band. The diffuser can be arranged with materials and structures with large sound absorption coefficients. In the movie recording studio, in order to dub, the layout of the indoor screen must also be considered.
There are many sets, props, and lighting equipment in the TV studio, and the sound field is well distributed, so there is no need to install a diffuser.
Sound quality decoration materials and their construction quality have a great impact on sound quality effects. Construction must be strictly controlled. Acoustic measurements (see Architectural Acoustics) and subjective evaluation of sound quality of recorded programs are required near completion, and necessary adjustments are made until So far. On the premise of meeting the sound quality requirements, the architectural art effect must also be fully considered when designing the recording studio.
Noise control In order to reduce environmental noise, we must start with site selection, general floor layout, sound insulation, and vibration isolation in accordance with the requirements of various recording studios, and combine them with the allowable building noise standards and noise source conditions.
Noise tolerance standards When designing a recording studio, you must first determine the noise tolerance standards to be used. The noise tolerance standards of various recording studios are shown in Table 3. In the table, NC is the noise evaluation standard (see Building noise tolerance standards).

Both Japan and the United Kingdom have adopted similar standards, while Federal Germany has adopted stricter standards.
Site selection The recording studio should be selected with convenient transportation, low environmental noise and a wide area. The recording studio site should be far away from areas and facilities with high noise and vibration such as airfields, railway stations, railways, ports, factories, and traffic arteries, in order to simplify the sound insulation structure and reduce the construction cost.
The overall layout of the outdoor noise should be measured, and the distance between the recording studio and the noise source should be determined based on the actual measurement results and the recording room noise tolerance standards. In the general arrangement, it is also necessary to keep the facilities with high noise and vibration such as refrigerator room, boiler room, garage, set production workshop and the recording studio at a sufficient distance.
The layout of the recording studio should be as far as possible to avoid language recording studios, reverberation rooms, etc. with low sound pressure levels directly adjacent to music recording studios with high noise (program sound pressure level); avoid directly adjacent to large and medium-sized TV studios, To simplify the structure of sound insulation and vibration isolation. Recording studios should generally not be directly adjacent to elevators, toilets, air-conditioning rooms, etc.
Source of interference The sound of various recorded programs is a source of interference to other recording studios. When designing the sound insulation structure of a recording studio, it is necessary to understand the noise of the interference source in order to calculate the sound pressure level of the recorded program based on the measured sound power levels of various programs and the indoor acoustic conditions of the recording studio under consideration. The noise level of the interference source at the time of sound insulation.
Sound insulation and vibration isolation According to the noise tolerance standard of the recording studio and the noise level of the surrounding interference sources, consider using a single or double 12-49 cm thick brick wall (or a concrete wall of similar weight) and a single layer of about 10 cm thick Or double concrete floors. Leave a gap of more than 10 cm between the double wall and the double floor. When necessary, the sound insulation and vibration isolation structure of the recording studio can also be made into a room in the room. The inner room is placed on the floor of the outer room through elastic cushions (metal springs, glass wool pads, etc.), and the other five sides of the gap are filled with sound absorption. Materials to improve sound insulation. In high-rise buildings, in order to reduce the load, materials such as aerated concrete or gypsum board can be used for the internal wall. In order to avoid the interference of environmental noise, the recording studio should not be provided with windows, and mechanical ventilation or air conditioning should be used. Ventilation and air-conditioning systems must be silenced (see Noise control of ventilation and air-conditioning systems) to ensure that the noise of the recording studio does not exceed the allowable value specified in Table 3. According to the sound insulation requirements, the communication window between the recording room and the control room should use 2 to 3 layers of glass with different thicknesses to improve the effect of the anastomosis effect. The recording studio should adopt a double sound insulation door, and a sound lock should be set in between.