Memory is a funny thing. Sometimes just the simple smell of bread baking in the oven or the sound of children laughing can trigger vivid memories of something that happened to you many years before, and with such detail that you’re amazed by your powers of recollection. Then you start looking for the keys that you put down somewhere just five minutes ago and they’ve vanished, leading to hours of fruitless searching before you realize you left them in the door. Equal parts endlessly amazing and frustrating.
Sensory memory, that which is gleaned from our five senses, is the most short-term form of memory. The amount of time between the information being captured and processed and when it can be retrieved and used is only mere seconds to minutes. The areas of sensory memory that have been most keenly studied by researchers are iconic, or visual input, and echoic, or auditory input.
We all know that the eye is one of the most complex parts of our body, but as anyone who’s spoken to a specialist hearing organization such as Hidden Hearing will be aware, the workings of the ear are also extremely elaborate. Any damage to the ear and how it performs can have an effect on echoic memory.
So, what exactly is echoic memory and what does it even do? Essentially, it’s the way that the brain replicates a sound as its received—someone coughing nearby, a word said during conversation, a car backfiring—and retains it for a very short period, usually only 2-4 seconds. The easiest way to understand how it works is this: If you're talking to someone and you miss what they’ve just said and are about to ask them to repeat it, but suddenly you recall it. This happens because you're able to access your brain’s interpretation of it.
Basically, it gives you time to think! The brain takes these copies unbidden, and the most amazing part is that it sorts all of the sounds we pick up, during every moment of the day, and automatically filters them into what is of importance and should be retained in the short-term memory, and what can simply be discarded.
This knowledge was the result of experiments conducted by Ulric Neisser as recently as the late 1960s, and has since been expanded on so that, for instance, we know the span of our echoic memory lengthens as we get older.
Our short-term memories degrade rapidly, so if you do miss something someone says at a party and you’re distracted and unable to instantly recall what was said, chances are that you’re going to need to ask them to say it again. But echoic memory can also be distorted by other events, such as a stroke which damages the brain. Thus if a victim is shown a list of four single-digit numbers they may still be able to recall them perfectly, but if the numbers are spoken, they would be unable to recall them at all.
Similarly, if we suffer from hearing loss as a result of the natural aging process, regular exposure to excessive noise or infection, then that will have a negative effect on the amount of sounds that our brains are able to record and process.
Echoic memory is a vital brain function that serves us well in our daily lives, and the loss of it can cause major problems. Luckily, we can take steps to guard against such problems. Simple health maintenance like keeping blood pressure down, quitting smoking, having hearing checked regularly by specialists and wearing ear protection if you're going to be somewhere noisy for prolonged periods can all greatly reduce the risk of hearing loss, or health problems that could contribute to hearing loss.