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Man pointing to the sky in a drysuit and iwcs headset

Joining incoming transmissions or dividing them?

Headsets are a common part of our workplaces. Whether used in rugged noisy conditions, or in the office, they have become an important part of our ability to communicate efficiently. In this article I would like to discuss the differences between how we, as the human animal, hear and register sound. I will also discuss the difference between separating incoming transmissions in the L and R speakers vs having all incoming audio in both speakers simultaneously. Rounding it off with the importance of volume contra quality. I hope this can give you some food for thought next time you choose what to go with for your next mission critical operation or industrial intercom solution. 

How does sound filter to the brain under different conditions

Two main factors have an influence on how well we register sound. The dynamic range of the incoming sound, and the intensity of that sound.

Intensity would be what we usually understand as the volume of sound. How loud we hear it in our ears.

The Dynamic range roughly translates to what we usually understand as the quality of the sound.

It is important to know that by adjusting these factors we can affect the legibility of the incoming message. An increase in sound volume can to some degree negate a low sound quality. Similarly, a good quality of sound will negate a low volume. This can be important to remember in regard to hearing loss. Over a double increase in sound volume is needed to compensate for a halving of sound quality. This can in certain situations be detrimental to our hearing in the form of permanent hearing loss. Our ears are sensitive instruments, and we need to take care of them.

Two ears contra one

On top of the fact that we use both volume and sound quality to discern what we are hearing; we also take advantage of the fact that we have two ears to do this. In fact, an American study has shown that we decipher sound differently with each ear. The right ear hearing speech better and the left ear hearing music and song better *1. This is because we are “hearing” the sound in a part of our brain, where sound waves are deciphered. Each ear being connected to its own side of the brain and therefor being influenced by that brain-hemisphere’s predominant function. There is therefore a “marrying” of this information in the brain which adds a depth to sound that is above and beyond just volume and quality.

Deciphering multiple sounds

Group of workers in hardhats and coats all talking at once

Our brains are made to use small cues in sound intensity, direction, and quality to be able to create a 3D “image” of what we are hearing in our minds. Imagine closing your eyes in a room full of people talking. You will be able to discern which voices are closer to you, and where they are in the room approximately. You will be able to determine approx. how many people are in the room, by deciphering differences in their voices. Moreover, you will even be able to favor a certain voice or conversation, and “home in” on it, using your brain to block out some of the other talking, which now becomes background noise.

In practice

So, this is why headsets that collect all incoming transmissions in both ears work so well. Because they support our brains own ability to decipher different inputs and “home in” on what is critical or desired. We are working with our natural preferences. Your brain is an amazing thing to handle that with such ease!

Helicopter pilots interviewed about the use of headphones when having to decipher up to four external radios (plus intercom) at once are quoted as saying that they can do so with ease. Quickly their brain notices differences in how each individual radio transmits and which voice belongs to which. Categorizing, grouping, and organizing incoming transmissions in their mind.*2

These same helicopter pilots, when asked if they could benefit from a system which divided transmissions one to each ear (Only applicable with a max of two radios) were quoted as saying that it would feel unnatural to group transmissions in this way. They would have to “…think too much about it…”.

In conclusion

We are always as humans striving to increase our functionality and effectivity in our workplaces to increase efficiency, safety, and comfort. This is an honorable and noble mission, and we can be proud of ourselves for the progress we have made as a species. Sometimes imitating nature, and the natural way of doing things, and then tweaking it to increase the desired outputs can be the best way to reach our goals. The brain is an amazing thing, and we are just beginning to understand the capabilities of which it comprises.

*1 Quote Web: hear-it, Your ears differ, 2020, https://www.hear-it.org/Your-ears-differ-

*2 Quote: Captain ALS, SAR Squadron 722, Royal Danish Air Force. January 2020. Denmark.

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