November Meeting Notice
November 1999 Meeting Notice
| Subject: | A Brief Tutorial on Proximity
Effect |
| Speaker: | David Josephson, Josephson Engineering |
| Place: | Cogswell College, Sunnyvale, CA |
| Time and Date: | Nov. 2nd, 7:30 PM (refreshments at 7:00 PM) |
During the 1999 convention in New York, David presented a paper “A Brief Tutorial on Proximity
Effect” which is the basis for his talk for the San Francisco section. Many people are unaware of
this basic characteristic of directional microphones. The talk will cover basic physics of pressure
and pressure gradient in the near and far field, common methods used in mic design to achieve
directivity using pressure gradient, and the practical results for the microphone user. Two main
points will be discussed in detail, which are often missing from the literature on this subject. The
first is that proximity effect is an issue not only for close sound sources, where it causes bass
boost, but for distant ones too in many cases. The second point is that proximity effect can only
occur where there is pressure gradient — at 90 degrees to the mic’s axis, there is no gradient
and no proximity effect. Differences between theory and reality will be illustrated with near and
far-field measurements of several dynamic, ribbon and condenser microphones.
Mr. Josephson studied Electrical Engineering at UC Berkeley and was the chief engineer of the
university’s radio station from 1975 to 79. From 1979 to 89 he worked in geophysical sensors
and systems with survey contractors and with the equipment manufacturer EG&G Geometrics
in Sunnyvale. In 1989 he started Josephson Engineering to develop condenser microphones
for studio, stage and measurement. The company moved to larger facilities in 1997 and now
produces complete microphones and OEM microphone elements for customers worldwide.
Mr. Josephson holds three patents in directional microphone design and has given several
papers at AES section meetings and conventions. He has served the AES San Francisco
section as Vice Chairman and committee member, has chaired sessions and workshops at
AES conventions. He is now chair of the AES Standards Committee working group on
microphone characterization, and of the AES Technical Council committee on microphones
and applications.
Directions
click here for a map
From the East Bay - Take 880 to 237 west. Exit on Mathilda Ave. north. Turn right on the
frontage road and then left onto Bordeaux Drive. The meeting is in the auditorium.
From the Peninsula - Take 101 to 237 east. Exit on Mathilda Ave. north. Turn right on the
frontage road and then left onto Bordeaux Drive. The meeting is in the auditorium.
