Hearing Tester

Background:
In 1996, Etymotic Research, Inc. developed a product concept for a hand-held, otoacoustic emissions (OAE) testing device for screening for sensorineural hearing loss. The concept was conceived as a low-cost device to be used for screening infants and other individuals incapable of eliciting a voluntary response to standard screening instruments. At the time, the devices used in infant screening were expensive, cumbersome or difficult to use, and required operation by a specially trained professional such as an audiologist. (These devices included several OAE test instruments as well instruments based on other technologies.)

A 16-year veteran in the field of hearing technology, Etymotic Research, sought to introduce a reliable, competitively-priced instrument that could be easily used by nurses and trained volunteers rather than by hearing professionals -- and could produce results in a very short period of time. With many states legislating universal screening of newborns, Etymotic conceived of a Distortion Product Otoacoustic Emissions (DPOAE)* instrument that could simplify and reduce the costs of implementing universal screening programs.

Etymotic started with the development of a now-patented acoustical probe tip assembly with three acoustically isolated orifices -- two for delivering pure tones into the ear canal and one for collecting response tones (otoacoustic emissions) into a miniature microphone. Etymotic also developed a basic electronics scheme and working, proof-of-principle prototype proved the viability of their technology.

Looking for a design partner to bring the ERO-SCAN from a proof-of-principle prototype to a marketable product, Etymotic Research enlisted the product development services of BIT 7, Inc. (Mundelein, IL and Madison, WI). Etymotic came to BIT 7 with the probe tip assembly, a board** hardwired with wires and electronic components, and three ìblackî boxes (independently housing digital components, analog components, and acoustic measurement components). BIT 7ís task was to consolidate these items into a single, user-friendly, hand-held device for accurate screening both infants and adults. At the same time, the final design needed to maintain original performance criteria and comply with all FDA medical device standards.

Time frame:
Within three months of receiving the proof-of-principle prototype and product objectives, BIT 7 delivered a fully functioning prototype to Etymotic for functional testing, field testing, and marketing response. Incorporating feedback from Etymotic Research and typical users, BIT 7 then made several minor design modifications and, within a few months, delivered additional units for beta testing. Successful beta tests led Etymotic Research to launch the first production run of the ERO-SCAN Test System just seven months (including field testing) after enlisting the services of BIT 7, Inc. Circuit Works Corporation (Lake Bluff, Illinois), an electronic manufacturing services provider and sister company to BIT 7, Inc., is currently manufacturing and testing the ERO-SCAN for Etymotic Research.

Turn-key product development services:
By providing a full complement of electronic, industrial, mechanical, and software engineering services, BIT 7 was able to deliver a fully developed product design to Etymotic Research in just seven months. An important key to the rapid turn-around from design to manufacturing was the assistance BIT 7 provided in specifying all materials and identifying potential suppliers for ERO-SCAN sub-assemblies and tooling. For example, by taking advantage of BIT 7's solid working relationship with Circuit Works Corporation for, Etymotic Research avoided the time-consuming task of finding a suitable resource for electronic and final package assembly.

Design challenges and solutions:
- The ERO-SCAN, in effect, is designed to measure the microscopic movement of a hair cell (cilia) in the human ear. Accurate measurement of this movement (technically, the measurement of the otoacoustic emission) depends upon detecting movement alone, without interference from the operator, the subject, the environment, or the screening device itself. The greatest design challenge faced by BIT 7, was to design a hand-held instrument that was free of vibrational, electromagnetic, and electromechanical interference. That meant harmoniously combining digital and sensitive analog electronics, along with acoustical and mechanical assemblies into a single instrument that could easily be operated in one hand. The task was met with carefully designed electronics and mechanical features that isolated the sub-systems from one another.

- To fit a wealth of electronics in a small space, BIT 7 took advantage of surface mount technology (SMT). SMT enables a high density of electronics within a very small space.

- For durability, the ERO-SCAN needed to be impact resistant. With a molded housing of a polycarbonate/ABS blend, the ERO-SCAN withstood repeated drop tests from 6 feet onto a cement floor.

- The BIT 7 industrial design team incorporated ERO-SCAN features enhancing comfort and ease-of-use in an attractive, non-threatening design allowing simple, one-handed operation. When each test is complete, the hand unit is placed in cradle which downloads the data for printing and/or saving to a computer file.

- To keep manufacturing costs down, BIT 7 employed Design for Manufacturing and Assembly (DFM / DFA) principles throughout the design process. Each design consideration was weighed against manufacturing time and costs. For example, the housing provides snap-fit features for the printed circuit board assemblies. In addition, a minimal number of fasteners are used and a ìtop downî assembly method is applied to simplify assembly. As the direct result of low manufacturing costs, Etymotic Research has been able to introduce a high quality instrument at $4,000, a price well below that of competitive devices.

BIT 7, Inc., 2742 Agriculture Dr., Madison, WI 53718. Tel: 608-224-0377; Fax: 608-224-0455.