Audio Engineering

Microphone Technology 673

wavelength, λ. When this occurs, the sound fi eld is disturbed by refl ection from the
capsule’s diaphragm as well as diffraction by the capsule’s protective grid and the
microphone housing. The degree of this disturbance depends on the angle of incidence of
the sound and is greatest for direct incidence.

The acoustic pressure at the diaphragm for directly incident sound at high frequencies
can, in fact, exceed by several decibels that which would have existed in the free fi eld.
The free fi eld pressure is that which would have existed if the obstacle

pP

Ax ft

V

γ m π

0

0

cos ( 2 )

. (22.25)

Further Reading.....................................................................................................

Ballou, G. M. , Handbook for sound engineers , 3rd ed., Boston : Focal Press , 2002.

Beranek, L. L. , Acoustics , New York : Mc-Graw-Hill , 1954.

Brüel and Kjaer, Measuring microphones , Technical review: Naerum, 1972.

Eargle, J. , The microphone book , 2nd Ed. , Boston : Focal Press , 2004.

Morse, P. M. , Vibration and sound , 2nd ed., New York : Mc-Graw-Hill , 1948.