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Development of High-performance Microphone for
Announcers
At the commencement of digital BS broadcasting, the NHK News Center facility
and equipment were upgraded to be Hi-Vision compliant. A high-performance
microphone for announcers, developed at the STRL, has been used since
December 2000.
The microphones used at the News Studio for announcers are either the
double capsule type in a tiepin shape, or a boundary microphone placed
on a table. This time, we have developed a high-sensitivity, small microphone
with an improved SN ratio and reduced dimensions (See Picture 1).
 Double
capsule microphone
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| Microphones for announcers are equipped with two independent pick
up systems, main and reserve, to prevent sound failure even in the
case of trouble in the main line. To accomplish this, two diaphragms
are built into the tiepin type microphone case. This newly developed
microphone has improved sensitivity and size (approx. 27% the volume
of a conventional microphone). This is achieved by the adoption
of a rectangular diaphragm, and by changing the diaphragms location. |
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Boundary
microphone
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| A boundary microphone is used to make news programs fail-safe,
even if both of the systems in the double capsule microphone fail.
This type of microphone achieves higher sensitivity than ordinary
microphones through the use of reflective sound from the table.
In addition to its miniaturization (approx. 52% of the volume of
a conventional one), the application of a thin microphone capsule
has improved its sensitivity and SN ratio performance. |
| Table: Specifications of a
newly developed microphones
|
 |
Double capsule
microphone |
Boundary
microphone |
| Type |
Condenser |
Condenser |
| Directivity |
Omnidirectional |
Unidirectional |
| Sensitivity
(0dB=1V/Pa) |
-36dB (15dB improvement) |
-28dB
(15dB improvement) |
SN ratio
(standard sound
pressure:94dB (1Pa)) |
69dB (3dB improvement)
|
78dB
(11dB improvement) |
|
():comparison
with conventional type microphones. |
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