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Microphone preamplifier

Binaural microphones

Rotating Turntable

Spherical loudspeaker

High-quality miniature microphones for binaural recordings / HRTF measurements

For my spatial hearing research (1996 - 2005) at the Helsinki University of Technology, Laboratory of Acoustics and Audio Signal Processing I made severals designs using the Sennheiser KE4-211-2 capsules both for binaural field recordings as well as HRTF measurements. The capsule is small enough (diameter 4.75 mm ~ 3/16") to fit into the ear canals of a person, either blocked or open.

The Sennheiser KE4-211-2 capsules have been widely used for HRTF research. They are reasonably priced yet offer good quality (frequency response ca. +/- 3 dB 20 Hz - 20 kHz, maximum SPL ca. 142 dB lin. @ 1 kHz, THD = 3 %). The hum is reasonable (A-weighted, DIN IEC ca. 26 dB; CCIR-weighted, CCIR 468-3 ca. 39 dB).

KAR-BMPF microphones for binaural field recordings

The design for binaural field recordings is robust enough to sustain the wear and tear of heavy use. An extra re-formable frame, shaped to the size and form of an average pinna, makes it easy to install and wear the microphone, as well as enhances the robustability. The skin-colored kevlar reinforced cables and Neutrix Nanocon connectors are used for maximal rigidity, while connected to the taylor-made preamplifier, KAR MPA10E. Model KAR-BMPFe is aimed for extended SPLs involving Sennheiser KE4-211-7 capsule (diameter 4.75 mm ~ 3/16"; frequency response ca. +/- 6 dB 20 Hz - 20 kHz, maximum SPL ca. 172 dB lin. @ 1 kHz, THD = 3 %; hum A-weighted, DIN IEC ca. 36 dB; hum CCIR-weighted, CCIR 468-3 ca. 49 dB).

KAR-BMPF microphones on a Cortex MK II dummy head
KAR-BMPF microphones worn on a Cortex MK II dummy head.

KAR-BMPH microphones for HRTF measurements

The KAR-BMPH model, applying Sennheiser KE4-211-2 capsule, is taylor-made for HRTF measurements. In other words, the cabling involves less re-inforcement compared to KAR-BMPF and a 90 dgr angle for the cable so that the capsule fits well to the (blocked) ear canal entrance. The KAR-BMPHk model uses kevlar-reinforced cabling for high robustabily against tear and wear.

KAR-BMPH microphones on a Neumann KU 100 dummy head
KAR-BMPH microphones worn on a Neumann KU 100 dummy head.


The KAR-BMP microphones are in use, e.g., in the following research institutions: