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ELC Audio Engineering
1534 N Dorsey Ln Tempe, AZ 85281


ELC Audio Engineering and Cochlear Concepts are currently developing a new cochlear implant (CI) processing strategy and active-circuit electrode array. For additional information, please visit Cochlear Concepts' FAQs page via cochlearconcepts.com. Cochlear Concepts also develops controlled, real-world auditory environments (with occasional video stimuli) for speech & hearing science research. It is our belief that the external validity of investigations regarding cochlear implants, hearing aids, and hearing protection devices will be enhanced by the use of periphonic systems that utilize Ambisonics (not to be confused with ambiophonics). High-order Ambisonics is an appropriate technology for testing hearing aids and cochlear implants because the sound field is reproduced correctly in the middle of the loudspeaker array--as opposed to wave-field synthesis (WFS), where the error is spread around the whole area of reproduction. Our Ambisonic recordings were made in a variety of establishments, to include "quiet" restaurants and coffee cafés. Recordings of quieter establishments are useful for studying cochlear implant processor strategies because the judicial use of moderate background noise allows the researcher to maintain positive signal-to-noise ratios (e.g., + 10 dB) that accurately represent real-world scenarios. The recordings were made using a specially designed Ambisonic microphone to capture each sound sources' direction (in the horizontal and vertical directions!) as well as natural reverberation. The raw (A-format) recordings were 24 bit, 96 kS/s digital recordings. Many of the B-format files and multi-channel stimulus files have been dithered to 16 bit for portability.

Future postings on this site will include information on how ELC Audio Engineering / Cochlear Concepts re-creates soundfields in the laboratory--just as they existed in the real world. In the meantime, interested parties are encouraged to read related articles from The Hearing Journal and Acta Acustica united with Acustica. It should be noted, however, that our Ambisonic surround system incorporates live recordings in addition to auralization techniques utilizing room impulse responses (RIRs). Cochlear Concepts will also be providing information on the development of ergonomic participant interfaces with embedded microcontrollers. The microcontroller-based interfaces are used to automate stimuli presentation and data acquisition for experiments performed in our virtual listening environments. While this website is new (last update: December, 2011), Cochlear Concepts will soon be adding links to our research, articles on Ambisonics (with permission from their respective authors and publishers), and the mathematics behind spherical harmonics. Note: Spherical harmonics should not be confused with the usual definition of "harmonics" that we often encounter while discussing sound or music. Spherical harmonics are, in a nutshell, the angular portion of a set of solutions to Laplace's equation, first introduced by Pierre Simon de Laplace (click here for Wikipedia link to spherical harmonics). Ambisonics, largely developed by the late Michael Gerzon (Professor of Mathematics, University of Oxford), is mathematically based on spherical harmonics.

Many thanks to Dr. Bengt-Inge Dalenbäck of CATT-Acoustic (www.catt.se) and Dr. Pauli Minnaar of Oticon (www.oticon.com) for their insight, suggestions and kind words. A brief blurb about yours truly that appeared in The Hearing Journal can be seen here (I appear on pages 14-15). A draft of my paper titled "Ecological Considerations for Cochlear Implant Research" can be accessed here. A PowerPoint presentation that delineates this paper and includes photos can be accessed by clicking here (the file is currently titled psy591 ecarmich).

A short list of articles by Eric L. Carmichel (author of this site) can be viewed here. Please click CV for my curriculum vitae. I can be reached at


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