Meeting Review, September 13, 2007
However, Dr. Warren was quick to point out that as people more familiar with traditional electrodynamic transducers encounter this application, it is important to understand the desired acoustic response curve is not the traditional “flat” line targeted by many loudspeaker designers. The reason for this is that in free-air, sounds travelling past the soft portions of the outer ear, and the horn-like cavity at the entrance to the inner ear, have an “ear transfer function” applied to them, and this response has a sizeable peak in the midrange frequencies, plus a dip in the higher frequencies.
At this point, Mr. Llamas-Young took over, and pointed out some specifics of the Knowles’ balanced armature transducers, including some of the electroacoustic models, and how various component parameters may be varied to affect the acoustic response of the finished transducer. In particular, Mr. Llamas-Young highlighted one of the newest and smallest Knowles units, the FK receiver which has been used very successfully in the in-ear application, due to an ability to combine and filter multiple FK’s into woofer/tweeter-like combinations for dual-receivers or other multi-receiver combinations.
Following Mr. Llamas-Young’s talk, visitors got to see highlights of several development and test labs featuring such items as production testing of balanced armature receivers, prototype assembly of Knowles’ SiSonicTM surface mount microphones, and other activities. An enjoyable time was had by all attendees, and the Chicago Section thanks Knowles for opening it’s doors to us for this special event.
Dan Mapes-Riordan (center) and Jeff Segota (right) look on as John Beard demonstrates the KEMAR head and torso
simulator in the Knowles anechoic chamber.