Happy New Ear!

01/01/2016

Blog post by SimGHOSTS President Scott Crawford, MD, CHSOS

Audio monitoring and recording of a simulation room is arguably the most important portion of an A/V system.  While many rooms have one-way glass for viewing, the only way to hear what is happening in a room is through microphones and recording, unless you are physically inside of the room.  This discussion will describe features and limitations of audio reproduction systems for use in your control room. Speakers are one of the easiest options for sound reproduction and can be built into a computer that is connected to a large A/V system for remote viewing, or may be an independent part of an analog output directly from a microphone in the room. Wireless Bluetooth speakers can be easily implemented either as an integrated unit (receiver and speaker) or as a Bluetooth receiver connected to a larger speaker system. Each option has pros and cons.

 

Speaker connection type   Pro  Con
 Computer based A/V system (IP)  -Remote accessible
-Low cost
-Small space
-Low audio quality (often)
-Audio delay
-Requires a computer and 
program 
 Analog connection  -No delay
-Can be used with any speaker or system
-Best quality available
-Expensive
-Requires direct wiring 
 Wireless connection (Bluetooth)  -No wires
-Portable
 -May require battery
-Pairing or frequency 
matching required
-Limited distance
-Potential security issues

 

Speaker systems in general work well to allow many people to listen at the same time while still being able to talk behind the scenes about elements of a scenario or specific learner actions. If the control room is adjacent to the simulation room, however, audio may be heard through the wall or out into the hallway, allowing for feedback or eavesdropping by other learners. This design does not work well in a room with a shared control room space (one control room to view and operate multiple learner scenarios) due to cross talk from the adjacent scenario. Depending on the center’s design and scenario type, speakers may still be the easiest and most cost effective option.

 

Headphones have made some major improvements since the Walkman of the mid-80s. Now earbuds, on-ear, over-ear, open back, closed back and noise canceling options can confuse this technology. If your control room is a shared space, has remote or direct viewing, headphones can provide private listening for one or many observers.  Headphone splitters and headphone amplifiers can expand this option with little additional cost.


Earbuds are the smallest and usually cheapest option, but these can make it difficult to hear those around you if talking is required due to the noise isolating nature of their design. Use in a shared space is problematic because many people do not wish to share a product that is inserted into another person’s ears.

 

On-ear designs are the more traditional design, heralding from the era of the Walkman. Although quality on these has  improved, they may appear cheap and often are. Because they do not plug the ear or cover it, they can allow for communication from a facilitator, educators and operator more easily. Despite the term on ear, some may have the appearance of their larger over ear counterpart due to the large vinyl surround.

 The “Professional” design, appearance and features of over-the-ear headphones make  them an excellent solution for simulation centers with shared space, or noise pollution concerns. The hygienic concerns of earbuds are removed, and the comfort and adjustability for all-day wear become clear after a single day’s use. This style of headphone usually ships with a ¼” stereo connection, allowing them to interface with professional audio equipment from splitters of large-scale installation systems. The important features of these headphones to learn about before implementation are open back, closed back and noise cancellation.

 

An open back headphone allows outside noise to penetrate the ear cup more easily so talking can still occur between adjacent wearers. A closed back design provides a physical blockage for outside noise, which is great if working around significant cross talk or noise, but can inhibit communication with a wearer. Noise cancellation may seem like a good option to remove outside noise, but it requires power and frequent battery changes. Noise cancellation was designed to remove a persistent hum or constant background sounds (like what may be encountered on a train or airplane) by reproducing an inverted sound wave to the wearer to “cancel” the outside noise.  This does not work well for removing variable noise, talking or clatter, because the inverted signal is both low in volume and not fast enough to minimize all outside sounds. Noise isolation from earbuds or closed back headphones is best for this concern.