Abstract
The sensitivity of condenser measurement microphones depends on
the environmental conditions due to the changes in the acoustic
properties of the air enclosed between diaphragm and backelectrode
and in the cavity behind the backelectrode. A theoretical
investigation has been performed based on an extended lumped
parameter representation of the mechanical and acoustic elements
of the microphone. The extension involves the frequency dependency
of the dynamic diaphragm mass and stiffness as well as a
first-order approximation of resonances in the back cavity. It was
found that each coefficient, for a given type of microphone, can
be described by a single function when the coefficients are
normalized by their low-frequency value and the frequency is
normalized with respect to the individual resonance frequency of
the microphone. The theoretical results are supported by
experimentally determined coefficients for about twenty samples of
microphone types B&K 4160 and B&K 4180.
| Original language | English |
|---|---|
| Journal | Metrologia |
| Volume | 36 |
| Issue number | 4 |
| Pages (from-to) | 265-273 |
| Publication status | Published - 1999 |