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Kids Wail Into Lectrosonics Wireless

Orfield Laboratories bravely recorded kids like this happy camper for the University of Minnesota’s Tantrum Study.

While most of us would wince or cover their ears at the wails of childhood tantrums, David Berg and Steve Orfield of Orfield Laboratories are looking for ways to record those unpleasant moments. In late 2001, Prof. Michael Potegal of the University of Minnesota Department of Pediatrics approached Minneapolis-based Orfield Labs—a company that specializes in acoustics vibration, vision, lighting, architecture and market research—about choosing and testing equipment for a study that required the acoustic monitoring of children in the midst of a tantrum. Orfield Labs’ task was to devise a means of recording the children’s vocalizations in an “accurate and unobtrusive manner.”

To capture and record the study’s associated histrionics effectively, Berg insisted on a wireless recording system. “In all cases, we needed equipment that was accurate, compact, durable, and easy to use,” says Berg. The recorded all sounds via a miniature microphone embedded in a vest worn by the child. A compact wireless transmitter would also be located on the vest, and its associated receiver and a digital recorder would be located nearby. Once recorded as .WAV files, tantrum audio data could be transferred to audio workstations for evaluation and further manipulation.

Orfield Labs’ recording rig included the Lectrosonics MM400A transmitter, Lectrosonics R400 receiver, Countryman model EMW microphone and the Marantz PMD670 digital recorder. “When selecting the wireless link for our project, we had several general requirements and several additional requirements specific to our needs,” explains Berg. “For the transmitter, we needed a compact and durable package with minimal controls and a usable battery life. The receiver’s form-factor was less important, but the link required high dynamic range, wide frequency response, and low noise. A requirement specific to our use is faithful reproduction of the dynamic character of the signal being recorded. For this reason, we chose a system that eliminates the compandor circuitry found in most wireless links. The Lectrosonics 400 Series wireless systems utilize a digital hybrid technology that eliminates the need for compandor circuitry.”

The MM400A miniature transmitter uses Lectrosonics’ compandor-eliminating Digital Hybrid Wireless operational technology, which combines 24-bit audio with an FM radio link to suppress noise and improve fidelity. Features of the MM400A include 256 synthesized UHF frequencies, 100mW of hearty output power, wide range input limiting, dual bicolor LEDs for indication of gain adjustment, and a waterproof machined aluminum casing.

The R400 Digital Hybrid Wireless receiver has 256 UHF frequencies and is compatible with all 400 Series transmitters as well as many analog models. The unit provides a backlit LCD display, a balanced XLR audio output, and a compact, sturdy chassis.

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