Andrew Bellavia (Twitter) of Knowles Corporation gave a talk at AES@NAMM 2018 last month on the 27th of January and went into depth about the acoustic science behind in-ear monitors and multiple balanced armature acoustic design.
Even if you’re not a technically-inclined person, the talk is a great listen with just the right amount of technical detail for almost everyone to learn something new! Mr. Bellavita talks about the new GRAS 43BB system designed to supplant the old IEC 60318-4 (formerly the IEC 60711 standard), artifactual higher-order distortions measured from balanced armature IEMs because of resonances at fundamental frequencies, exactly what goes into a custom-ordered balanced armature (versus a general version with well known part numbers, e.g. ED-29689, TWFK-30017), and the most important design variables within a multi-driver system. Also included within the talk are preview slides of how Harman (now part of Samsung) tuned the new flagship 5-driver AKG N5005 to match their modified Olive-Welti equalization target. In other words, this video is a MUST WATCH! Happy viewing!