You Don't Know What You Don't Know

In my career I’ve remained curious and in so doing have tended to ask questions going another layer deeper. I’ve sought the “why” behind the “what.” The most satisfying answers have been those that elicit the reaction, “I wouldn’t have even thought to ask that.” I can’t tell you how many times I’ve not only known something but didn’t know it was something to even be known. Let’s look at a few of the surprising examples I’ve picked up along the way.

27”

When first designing direct-view LED displays, we wanted them to float above the upstage portion of the stage. We knew about the ADA requirement to have the bottom above 80” so that people wouldn’t hit their head, but we also knew that being right at the floor was okay. So what if we raise it an inch? Two inches? We knew these would’ve been fine at those lower heights, but what would be the upper limit when it becomes unsafe again? Two feet? Three feet?

So I did some reading up on the ADA to find the answer. Turns out it’s 27”. If it’s floating out in space or more than four inches from the wall, below 27” is good and above 80” is good. What was surprising was the reason why. The ADA considers obstructions below 27” to be within the cane sweep of those who use canes to accommodate visual impairment. Further, if an obstruction is within that 27”-80” range, placing a barrier under 27” as a warning for the object above is acceptable.

While I did think of the question of what the lower limit was, I did not think to pursue the question in terms of cane sweep. Even more, there is a certain arbitrariness to the answer. I don’t know why it’s 27” as opposed to 24” or 25” or 30”. It may have been the product of careful research locked up in academia. It may have been a truly arbitrary product–within a reasonable range but some number, or any number, so that a standard could be enforced. Without already knowing the answer, it would be very difficult, if not impossible, to arrive at the right answer with any confidence.

Subs and Sharks

I was part of a design team for an AV system within an under-the-sea type exhibit. It was an aquarium setting with immersive audio and video. When the design went under review by the owner, their animal care specialists came back with notes.

The audio system had been of a fairly standard distributed design, with HF drivers throughout the space with the special element of some speakers being embedded within the scenery and subs centralized for low-end extension. The animal care specialists requested that we remove the subs because the lower frequencies were disturbing to the sharks and other wildlife.

Once we were told this, it was seemingly obvious, but it revealed a blind spot that we would not otherwise have considered. We were proficient at designing systems for human experience, even taking into account Fletcher-Munson curves (describing how well humans perceive various frequencies) and other accommodations to human physiology and the psychoacoustic phenomenology of sound. We were so finely tuned to designing for humans that we were deaf to designing the experience for other species.

We were also proficient at designing sound transmission through the medium of air. This project introduced the need to consider when that air transmission meets the medium of water. While the animal experience of sound and the transmission of sound through water can each be rich fields, both beyond the expertise of general system design, sound designers can know to ask the right questions of the right experts. These are questions they might not have even thought to ask without that specific experience.

RF on the River

The next task was a difficult one. It was a deployment of wireless microphone antennas set to cover 40,000 square feet. This would be comprised of several zones merged together in what was expected to be a busy RF environment. This included the usual cellular traffic, Bluetooth and wireless access points. To complicate matters the room was full of devices with wireless monitoring capabilities for security and regulatory compliance.

As a matter of practice, we would prefer to measure the existing RF noise floor and target clear frequencies where we could achieve significant signal to noise ratios. However, the monitored equipment was set to arrive only after the system was designed and installed and then the patrons with their cell phones after that. We needed a system beyond bedrock solid to anticipate whatever RF environment this room would become.

So, I worked with several manufacturers to develop the strongest design possible. One of them pointed me to a detail I would not have otherwise considered. The site was next to a river busy with shipping traffic. Apparently the frequencies used for maritime communication interfere with several frequencies used by wireless microphones. I would never have thought to consider boat traffic in designing a wireless system.

This insight from the manufacturer not only directed us to frequency selection and certain band-pass filters but also informed the orientation of the antennas. We were using directional antennas; simply having them point away from the river saved us from interference.

Many of us are generalists and integration firms like mine specialize in integrating the various technologies. That specialty often comes at the cost of letting others carry the burden of unsoundable depths of knowledge in narrow fields. Relying on their subject matter expertise is crucial. There are questions we wouldn’t have thought to ask that we may encounter only a handful of times in our career. These are the questions they answer every day.

We will continue to encounter questions to which we do not have the resource within ourselves to answer. We may not have the experience to even ask the questions. But if we stay humble and curious and rely on the expertise of others, we can continue to grow and develop designs that concentrate the knowledge and experience of an entire industry. We may not always know what questions to ask, but we can always remember to ask for the guidance of subject matter experts and optimize the design for every person (and animal) who experiences it.