The audio mobile truck is a special-purpose vehicle equipped with materials for live broadcasting and recording sports (baseball, golf, etc.) and music events. Regarding the functionality, it is the same as a sub control room and editing room in a broadcast station in which people can switch pictures, make recording, mix sound and finally transmit them. Especially, the audio mobile truck specialized in sound carries a large console like a recording studio and it accommodates not only for broadcasting but also making live-recording of concerts which require many recording channels. Requests for surround monitor environment have been increasing along with the popularization of surround contents such as terrestrial digital broadcasting and DVD. A sub-room is prepared in the audio mobile truck and used when a concurrent job is preceded for a 2ch-mixdown.
We also have an audio mobile truck for marathon broadcast, which has a recording room like a commentary-booth. However, there are so many restrictions to manufacture an audio mobile truck which is different from construction in a building.
The most difficult tasks are to build a monitoring environment for a studio in a narrow space of a vehicle. The design technique to give the fine acoustic treatment with maximum efficiency in the limited space is needed, because of space for the sound insulation and sound absorbing is not enough. Moreover, this truck is essentially required to pass a car inspection for special use vehicle. Concerning the live load and the interior material, limitation exists, therefore special know how is necessary to design an audio mobile truck , for example, the weight balance for each wheel and the method of interior construction well cared for safety of installing the equipment while driving.

Sound Insulating Construction

An audio mobile truck cannot get enough sound insulation from only steel sheets that cover the truck because it is mainly parked in an outdoor space where the noise level is high. To obtain a silent monitoring environment, using a double or triple reinforced sound insulation wall which is inserted materials for sound absorbing or dumping are needed for the truck. If the truck is equipped with a motor generator as a power supply unit, countermeasure for the sound insulation is the most important job during the design phase because the motor generator is the biggest source of the noise and vibration. Using Noise Vision, we can search the weak point of the sound insulation and examine the effective point for reinforcement and then we can create a precision countermeasure for the sound insulation.

Air-Conditioning Facilities

To secure the silence (usually NC-25 to 30 approx) in the monitor room, creating a muffling arrangement for the air conditioning unit becomes important. First of all, to set a noisy air-conditioning unit (both indoor & outdoor unit) outside the monitor room and to install a flexible mounting will prevent the noise and vibration from getting inside the truck. Secondly, to reducing not only the wind noise and the mechanical noise radiated from the air conditioner itself but also the crosstalk from a motor generator, we will install a silencer within the narrow space under the roof. Moreover, we will propose an air condition design to achieve a cozy work area environment within a tight space, for example, creating a countermeasure against condensation in the air outlet and the air outlet layout located except above of the operator and console.

Because an audio mobile truck has exceedingly narrow space inside and a slight difference of the room acoustic treatment and the mounting condition of the speakers will be appeared more remarkably than a common studio, a better detailed design is needed. Therefore, we will pay close attention to the environment around the speakers and study the setting method to fully educe the performance of each speaker.
Regarding the low frequency range, a narrow audio mobile truck can easily receive influences of the standing wave to the higher frequency compared to a studio. We recognize the importance to examine the efficient acoustic treatment using a wave motion sound simulation and to realize a well-balanced room sound field from low to high frequency range.
Moreover, we intend to do sound field creation where our customer will not have a cooped-up or oppressive feeling while working long hours in a tight space and finally to complete a sound field fit for the needs of our customer, sharing the process of sound tuning with them.
Additionally, we will provide various ideas and devices for tight spaces, for example, adopting a movable mount for the console and rear speaker to improve equipment maintenance and to secure maximum work space.