BRUEL & KJAER 4111 - Page 5

2
Fig. 2 shows an exploded view of the instrument.
The other end o.
the tube tapers and continues as a self-supporting goose neck with
a length of 400 mm.
This terminates in a 7-pin plug, directly fit-
ting the socket marked "Condenser Microphone" on the amplifier or
analyzer. It is thus possible to mount the microphone directly on the
above mentioned 3 pieces of apparatus. By bending the goose neck the
microphone can then be placed in any desired position.
Fig. 2. Explodea view of Condenser Microphone type 4111.
The sensitivity of the microphone, about 2 mV per fbar, is compara-
tively high, particularly when taking into acc..ount its small dimens-
ions and high re~onance frequency. The accurate sensitivity of each
individual microphone as well as the total frequency response charac-
teristic are shown on a recording in the back cover, made individually
for each r."licrophone delivered. Fig. 3 shows an arbitrary example of
such a calibration curve. Both the sensitivity (ex,pressed in mV/fbar
(==dynes/ em
2
)
or decibels below 1 volt/fbar) and the frequency response
are valid for the sound waves of a free sound · field impinging normal-