At present, the handling of sound signals requires careful attention to accurately locate audio levels. With the new sound reproduction systems, it is important for the sound engineer to achieve maximum sound power with the minimum of distortion components to use all available dynamic range.
With this range offered by digital audio and the bandwidth available for sound production in film and video, this has become a fundamental aspect that requires new monitoring methods and the establishment of maximum degrees of safety in which a sound system can operate.
With these arguments, a series of specialized measuring instruments have emerged for the management and control of both analog and digital audio signals. Dolby Labs, a company recognized for its research work in sound and the development of technologies applied to the television and film industry, offers a portable diagnostic tool for audio monitoring, capable of measuring Dolby bitstreams (Dolby Digital, Dolby E) and PCM (Pulse-code modulation). The DM-100 enables system integrators and service engineers to quickly perform bitstream integrity and composition tests on production, broadcast and home theater systems.
The DM-100 identifies the input stream format and decodes it appropriately. By using headphones users can monitor pairs of individual channels or two-channel mixes of any multichannel program, while the sum of the two channels can be heard on a small speaker that comes included. Test flows are stored in a non-volatile internal memory of the RAM type and can be changed in the field via software update.
Moreover, Dolby Labs also offers the DP570 multichannel audio tool, developed to simplify the process of multichannel audio monitoring and dolby digital metadata creation with minimal professional audio effort. This processor also allows the user to hear the metadata effect in real time while preparing the sound tracks to be sent at the end as Dolby Digital bitstreams. The DP570 accepts eight channels of audio input and processes them according to metadata values chosen by program creators, including values for compression dynamic range, mixing characteristics, and settings for the program channel.
Audio Precision, developed a new accessory for audio performance testing on PC. With Microsoft Windows certification, this resource offers a complete solution for explaining, tuning and testing audio behavior on any PC installed on Windows platform, according to Microsoft Hardware Quality Lab (WHQL) specifications. The audio system input and output sections of a sound card or motherboard are fully tested using the capabilities of the System Two audio analyzer. Several paths of each PC audio system are tested to deliver a full performance image of both the audio mixer and the entire system, including the converters.
For sound monitoring of 5.1 and 7.1 Surround formats, the company Logitek Meters developed the SV51, UV51 and UV71 measurement systems. These measuring instruments use digital signal processing based on SHARC DSP analog equipment, for accurate measurement that correspond to international standards. All meters can be configured to accept analog or digital inputs. The SV51 has six LED graphic bars. Analog inputs are able to receive balanced and unbalanced signals. These units can be calibrated as a reference between –10 to +24dBu. Digital models accept professional or consumer digital signals and automatically secure the sampling rat of input signals.
In the same line of systems for Sound Monitors Sourround, Leader Instruments Corp. offers the LV 5836B model, a device capable of exposing an accurate image of sound that exactly equates to the aural perception of the human ear. Developed in collaboration with NHK, the Japanese broadcasting company, this digital processor works out of phase and amplitude aspects to display a sound image. The unit accepts the latest in the form of six channels of AES/EBU digital audio. A level indicator on the screen is dedicated to the low frequency channel. In addition, it accepts five analog audio channels in balanced or unbalanced form.
These measurement systems were recently presented at NAB 2000.
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