Image: Anthropometric and Human Factors studies. Monster Purity Pro, Nokia WH-308.

I have done ergonomics research and validation for many types of products: wearable, portable and stationary. My main focus area lately has been in ergonomics of different types of headsets: over-ear, on-ear, intra concha, semi-canal and in-ear headsets, both wireless (Bluetooth) and wired.

In an ergonomics project the tasks include: anthropometric research, validation plan, benchmark product evaluations, project daily support (for designers, engineers and project management) and the actual ergonomic validation for the product.

Ergonomic requirements

The work starts from early concepts, where the research results from previous products, benchmark products and from anthropometric studies are used for defining the product concept frame and ergonomic targets. Learning from previous products and benchmark products are collected from actual end users e.g. via interviews, surveys or customer reviews. More detailed ergonomic benchmark evaluations are done by user testing. In ergonomics research it is important to achieve this way the comparison measurements, pressure targets and material comfort targets. In headset ergonomics, the measures and dimensions of head and ears are naturally needed. In addition, other human factors affect in wearable devices design: personal differences in sensitivity for pain or irritation, sweating, allergies, wearing glasses, amount of hair etc. All these variables need to be included in the evaluation.

The measuring should be done  both with machine to get accurate numeric data and with actual users testing to get the comfort evaluation which only can be provided by humans.

To get enough accurate data from the ergonomic user testing, the validation needs to be done using enough anthropometric variation in the  test user group. This is done by measuring enough amount of people, comparing the measurements to anthropometric statistics in different ethnographic population, and then choosing the test users to the group so that there are representatives covering the population percentile. Typically, it is difficult to find enough suitable measure matched test users without making really wide studies. Also typically, in product developement there is not much time to be spent in this phase of project, which means that compromises in validation often needs to take place.

Image: Ergonomic fitting tests in measured user group.

Ergonomic validation process

The ergonomic validation process is iterative. When project proceeds, enough many validation rounds are needed. More complex the product is, more testing is needed. Iterations should start by first validation the basic structure, adjustments and geometry, then in next rounds bring more variables in the test, e.g. materials audio and the physical UI. I have found it a good practice to divide the test areas clearly when project is in consepting phase. More full ergonomic validation rounds come in later phase of the project.

Ergonomic wearing tests should include quick first impressions, how does the headset feel when trying it out the first time (e.g. simulation of trying the product at the shop), comparing with benchmark headsets and then most importantly, wearing the headset continuously for a long period. Repeating these tests in the same format gives a possibility for comparison and following the improvement.

Physical UI ergonomics validation can be started by expert evaluations and then by normal user tests.  At the later phase of the project, more final ergonomic testing is done by using the headset for some weeks in normal, daily use and then collecting the feedback about wearing comfort, UI ergonomics and overall user experience in different context of usage.

Image: Physical UI ergonomics. Camera Grip for Lumia 1020, Nokia BH-121.