Welcome to the ELC Auditory Research & Engineering website.  This site is mainly used to post research regarding hearing science, instrumentation & measurement, and electronic design.  Expert consultation is available for organizations involved with the Speech & Hearing Sciences; Test and Measurement; Sound & Vibration Assessment and Control; OSHA Compliance Regarding Noise in the Workplace; & Electronic Design.  Please visit Cochlear Concepts (www.cochlearconcepts.com) for my latest ventures in hearing science. For information regarding our Excessive Noise Level Alerting Device / ENLAD® (US Patent 7315244), please see ENLAD.  The ENLAD® includes patented features for minimizing false triggers; it is NOT a noise dosimeter or SLM that simply triggers at a user-specified SPL or Leq.  Future & current research endeavors include Electrophysiology, Otoacoustic Emissions, Cochlear Implants, Psychoacoustics, Spatial Hearing, and electronic instrumentation.  Eric Carmichel's curriculum vitae can be viewed by going to cv-resume.  Thank you for visiting the ELC Audio Engineering website.

Caution:  The phrase "lend us your ears" is taken literally in this lab.

Eric L. Carmichel can be contacted at elcarmichel@elcaudio.com.

The PHANTOM (Profile Head for Acoustical Noise Testing & Otological Measurement) has two matched “ears” per side which allows simultaneous real-time comparisons of protected versus unoccluded ears.  Elliptical markings facilitate centering HPDs over the microphones.  A built-in strain gauge allows measurement of HPD headband force.  A thermocouple in one ear enables measurement of temperature.  Preliminary research indicates that the resiliency of foam earplugs varies with temperature, thus affecting the Noise Reduction Rating (NRR) of insert foam plugs.  See "The Big Bang!" by J. Carmichel & E. Carmichel, Outdoor Life (April, 2000) for my experience using foam plugs in a cold climate.

Localization study:  Three different styles of HPDs from three different manufacturers were investigated.  Stimuli were a (1) firearm loading, (2) telephone ringing, (3) 0.5-kHz FM toneburst, and (4) 4-kHz FM toneburst.  Localization responses and their respective response times were measured for eight normal-hearing participants.  For detailed information, click Localization below.  Please read 'Page 10' of The Hearing Journal, Vol. 57, No. 9, 2004 September, pp. 10-16 for author bios.  Go to HJ2004_09_pg10-16.pdf for HJ article.

For Localization Ability & Response Time with Binaural Electronic HPD / Electronic Earmuffs /

Binaural Electronic Hearing Protectors / Personal Hearing Protection, please go to

Noise & Health

The ELC Data-Recording System (Pat. Pending) records participants' responses and response times (RT).  This system was designed to be used with multi-channel audio recording software such as Cool Edit Pro or Adobe Audition.  CD-quality (or better!) digital recordings can be used to present aural stimuli.  Stimuli automatically presented at precise, experimenter-defined intervals.  Data recording stops if the participant does not make a selection within a specified time (part of the forced-choice paradigm).  An optional LED automatically flashes and gives the participant a visual "heads up" before each stimulus is presented.  For more information and photos of the hardware (minus computer), please see data collect.

For Firearm Muzzle Blast SPL Peak Pressure Levels (dB PPL) / Acoustic Trauma /

Noise Adverse Effects / Sensorineural Hearing Loss, please go to

Muzzle Blast

The Muzzle Blast (pdf) file below is 1.42MB, but it includes figures and tables.

Muzzle Blast PDF

ELC Audio Engineering's Visual Reinforcement Audiometry (VRA) System

Despite assumptions that TEOAEs, DPOAEs, ABR, or other physiological measurements will replace behavioral tests, Visual Reinforcement Audiometry (VRA) continues to be popular among Pediatric Audiologists.  The ELC Single-Button VRA System (Pat. Pending) can reduce tone presentation-to-visual reinforcement time, thus increasing the efficacy of VRA.  There's no hesitation selecting a Left or Right presentation button.  Only a single push button is needed because electronic memory 'knows' which ear the test tone was presented to.  Wireless (UHF or optical) connections make setting up our Toy Tier™ VRA systems a snap--there's no need to route wires through test booth walls!  Contact elcarmichel@elcaudio.com for details.

For our Vintage VT Audio Amplifier bibliography, please visit

Hi-Fi Amplifiers

For photos of my single-ended vacuum tube amplifier (one of many that I've built since grade school) see

SE 807 VT Amp

The paintings and photos below have little or nothing to do with anything else on this site. Have fun browsing!

Click thumbnail for paintings 1, 2, and 3.

Click thumbnail for paintings 4 and 5.

Conversation with a Lightbulb.

Single-Ended 807 VT Amplifier (top view).

Self portrait (egad!).