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September 1998

Headsets: The Technology Behind The Fit


The Problem
Telephone headsets are unique hybrid products that span the chasm between electrical componentry and ergonomic design. While the electrical-acoustic side of the equation is traditionally where one applies the label of technology, in recent years it has been the ergonomics of the product that have most enjoyed a technology boost.

Consistently, users of telephone headsets - whether they wear a unit all day long in a call center, or intermittently in an office environment - cite sound quality and comfort as the two most important product attributes, well ahead of durability or feature enhancements. And why not? Those of us familiar with headsets understand the tremendous productivity boost associated with their usage, but if it isn't comfortable, we're not going to wear it.

Product fit and comfort are the domain of human factors, the study of the interaction between products and the human body. Any product you wear, hold or otherwise touch - from sunglasses to shoes to the controls on your dishwasher - has passed under the watchful eye of a human factors specialist. Historically the process has been iterative, with product prototypes being developed, tested by customer focus groups and then sent back for redesign to incorporate user demands. The difficulty with this process is that it takes considerable time, it is reactive rather than predictive and it depends upon the opinions of a small group of customers. As often as not, if a comfortable headset fit was achieved, the success involved many cycles of hard work and no small amount of good luck.

Comfort is a difficult concept to define and an even more difficult metric to quantify. It is recognized that product fit is a component of comfort, but fit again defies measurement. The human ear is arguably the most variable of the external human organs and until recently, its physical layout had not been deeply studied, let alone mapped. The "take a stab at it and hope for the best" approach historically dominated headset design.

Several years ago, Plantronics, a world leader in communications headsets, began to rethink the paradigm. With millions of new headset users joining the ranks every year, and with concern over discomfort leading the list of reasons why headsets are rejected, an analytical approach to the comfort issue became a corporate imperative.

The Solution
In 1994, Plantronics commissioned the largest ergonomic study of the human ear ever undertaken. Hundreds of ears, appropriately representative by gender, age and ethnicity, were measured in excruciating detail. Three-dimensional laser scanning was employed to capture ear sizes, shapes, topography and placement relative to the mouth, cheeks and crown of the head. An enormous database was created and an entirely new vocabulary was developed to define ear features which, prior to this study, didn't even have names. From the cavum to the tragion, the apex to the concha - for the first time, a headset company had the data necessary to quantify its fit ratios analytically rather than anecdotally.

The next step, an infamously "gooey" chapter in Plantronics history known as the "Lend Us Your Ears" program, was to create a representative sample of ear models. Several hundred Plantronics employees went through the same laser scanning as the original study participants. From those measurements, a subset of employees was chosen that represented the full range of ear sizes and shapes. Those employees then endured having a mold taken of their ears, a messy and disorienting process involving having a blob of "gooey" clay-like material held to the side of their heads for enough time that the mold could harden. A synthetic rubber-like material - chosen for its similar pliability to actual human ears, was then used to create the models. The "Wall of Ears" was born, although for reasons lost in the corporate history logs, blue was the color chosen for the models, conjuring up images of Vincent Van Gogh and a large Smurf population.

These models permitted, for the first time, a statistical link between fit and comfort. With an available pool of fully measured human ears upon which to test, product models and prototypes could be created against the numerical database, then tested on live subjects. From those internal tests, further data was captured which accurately correlated the complex relationship between fit and comfort. A number of widely accepted assumptions about customer acceptance of headset products was relegated to the trash heap replaced by a new and statistically supportable set of design guidelines.

The new process, while a vast improvement over prior methods, still involved an iterative design process, although, by virtue of intelligent processes, a considerably shortened one. Rapid advances in computer technology, however, particularly in 3-D modeling software, have given new life to the original database. It is now possible to create electronic contour models of any of the measured ears. Industrial designers and human factors specialists can map the size range of the market population and determine with high statistical probability the percentage of the population that will accept a product as comfortable, long before a single model is generated. This has resulted in shorter development cycles, lower related costs, and, most importantly - higher customer satisfaction.

Refinement of the concept continues, with new and important information emerging on a regular basis. Ear contour analysis is yielding data not only on the test subjects but, through statistical extrapolation, on the entirety of the human population. Future development may permit Plantronics to design products unique to ethnic groups, geographical locations, gender, and age. The ability to simulate the weight and pliability of different materials in advance of modeling is showing promise of more flexible and body-conformable designs in a single package. Human factors technology will allow Plantronics to provide comfortably fitting units even to those who rejected headsets in the past.

The Results
No single headset product, either from Plantronics or from competitive vendors, has achieved a 100% comfort acceptance rate in the market. No matter how closely we study the ergonomics of the ear, we still must accept that individuals users are, frankly, individual, with unique likes and dislikes, in different body shapes and sizes.

It is already well documented that telephone headset usage boosts productivity rates, by a whopping 43% in a recent study. If, as a result of its analytical approach to human factors design, Plantronics can successfully fit one additional percentage point of the potential user pool, then over five million users will benefit from the research. Those new users, even at the most conservative payscales, will deliver back to their employers an additional forty-three billion dollars per year's worth of productivity - not a bad return on investment for a couple hundred gooey ears.

Nick Eisner is product marketing manager of Plantronics, Inc. Founded in 1961, the company is headquartered in Santa Cruz, California and maintains offices in 14 countries. Plantronics products are sold and supported through a worldwide network of authorized Plantronics marketing partners.

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