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Sounds You Can(not) Forget The relationship between our hearing sense and memory

Read more Last updated: January 2020
In collection Sounds
Reading duration: 8 minutes

‘Seeing is better than hearing.’ This proverb, in various forms, exists in a whole host of languages and dialects, ranging from African to Chinese. And it’s not just ancient wisdom that holds this idea to be true: modern research has demonstrated that the brain is better able to form memories when they are linked to sight, or even touch, rather than sound.

Message successfully transmitted

Although it’s known that the hippocampus plays a vital role in memory, past studies have primarily focused on this part of the brain’s ability to register spatial information, and less on its relationship with everything else - smells, sounds, tastes - that feed into the making of a memory. Researchers have since found that, although the hippocampus does have a relationship with sound, the paths by which various sorts of information are transported to our brains are not all the same - and some, it seems, may be more efficient than others.
There’s more than a little truth in the expression ‘in one ear and out the other,’ and it’s a reflection of the fact that the path by which sound makes its way to the hippocampus to be stored as a memory is not as effective as, say, the one by which sights and visual impressions are transmitted.

Auditory information, say researchers, is best retained with the assistance of repetition. This is why you may be introduced to someone and instantly forget their name, or get to the shop and have no recollection of what you were told to buy. At the same time, it’s why you may still remember the Latin conjugations for the verb ‘to be’, thanks to the endless classroom chanting led by your teacher, or know by heart the words of a song that’s frequently played on the radio.

Auditory memory’s reliance on repetition explains why we immediately recognise sounds which have become familiar through experience - the voice of a relative and the squeal of a boiling kettle, for example, or the ‘bips’ that signal it’s safe to step into the road at a pedestrian crossing.

The almost forgotten sounds

Even so, as modern life progresses and technological advances are made, there are sounds which are no longer heard on a regular basis. Mobile telephones don’t have dial tones, for instance, and laptops don’t offer the ‘clackety-clack’ of typewriter keys. Internet-based access to music and television means that we never hear the tangled shrivel of lyrics as the thread of a cassette tape gets mangled in the heads of a player, nor the mechanical slide of a video cassette into the belly of a VCR machine. The coming generations may never hear these at all - but would those sounds even be recognisable now to those for whom they were once familiar?

A hearing context

Where long term memory is concerned, it seems that there is often more to retention than repetition: context also plays a significant role. Without seeing hands flying across a typewriter, without the visual cue of the VCR, one might struggle to place the sound, despite its familiarity from years past. This is why radio contests, where a snippet of a popular song is played for an entrant to identify, often sees the caller confused and hesitant: removed from a broader context, the sounds are less recognisable.

Emotion provides another layer of context to our ability to recall sounds and it is for this reason that some sounds are impossible to forget. It has frequently been demonstrated that sufferers of dementia, or patients in a coma, will respond, however faintly, to the voice of a loved one, yet not to that of a doctor. Not only does repetition and familiarity play a part but, unlike a dial tone or electric kettle, certain sounds are loaded with emotional meaning - and, since the context is deeply rooted in the psyche, it doesn’t depend on other external stimuli, like sights, or a more complete picture for it to be recognisable.

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When we experience something with a certain sound, it can be filed away in our brains in a catalogue of emotions. Sensory information and emotional information get packaged together and stored in the auditory cortex - so, in the same way that a certain fragrance might take you back in your mind to Sunday afternoons in your aunt’s living room, sound gets imbued with an emotional meaning. Indeed, a group of researchers in Switzerland found that emotion plays a key role in the formation of memory and that strong emotional responses to certain sounds enhance the memories created around the particular experience associated with that sound.

The brain’s ability to contextualise sound also explains why we don’t react when we hear a siren while in the comfort of our own home, but may startle if we are driving, or on the street. It contributes to why a gunshot-type ‘bang!’ heard on New Year’s Eve might cause someone to think ‘fireworks,’ while on another occasion, more disquieting images may come to mind: our brains sort through our sound catalogue to make sense of what we are hearing and to trigger an appropriate physical response - in this case, either to look at the sky to enjoy the spectacle, or to take cover.

Sounds trigger emotions

Past experience, on the other hand, often means that some individuals have higher anxiety levels than others and for them, such loud or sudden noises may always elicit fear responses. For someone who has witnessed first hand the atrocities of war, it might be impossible to disentangle loud and sudden noises from horrific memories. In addition, Post Traumatic Stress Disorder (PTSD) has been linked with heightened sensitivity to noise, frequently meaning that even sounds that don’t have negatively contextual layers can be, at best, jarring and at worst, unbearable. In other disorders, the brain may struggle to find context, making it difficult for the sufferer to distinguish between sounds that ought or ought not to provoke certain fear responses, with generalised anxiety the result.

In the absence of these types of generalised anxieties, however, some sounds can produce almost universal responses in people: nature sounds, for instance, are nearly always associated with peace and relaxation, while the noise of a persistently ringing phone will spark irritation. Beautiful music promotes a sense of contentment or happiness, even if the listener doesn’t have a latent memory associated with the piece. It’s unlikely that many people have heard the otherworldly calls of dolphins in real life, yet listening to recordings is associated with heightened feelings of pleasure and peace. Sometimes the emotion itself IS the experience.

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Brains remember, memory forgets

When research has demonstrated that we have difficulty in holding on to the memory of sound without the presence of other factors, why then are we so receptive to it? One reason could be that our bodies are comprised primarily of water: a potent conductor of the waves from which sound is formed. Although debated by scientists, famous experiments performed by Japanese professor Dr Masaru Emoto examined the effects of various words and music on water, finding that, when examined microscopically, the water exposed to classical music and expressions of gratitude had formed breathtaking crystalline patterns, while the water over which violent music and words of hatred had been played had turned swampy and dull.

Crystalline patterns of water
The representation of the words "love" and "gratitude" in frozen water.
© Office Masaru Emoto

In the same way that not all responses to sound are based on experience, not all memories are formed from an easily identifiable event. Babies can hear long before they exit the womb, and are already developing their neurological and emotional responses to sound: one study demonstrated that, even though the subjects had only experienced a certain language in their earliest formative years and now had no knowledge of it, they still engaged the left side of their brain - the side with which speech is interpreted - rather than the right side, by which sounds are interpreted - to make sense of the language to which they were exposed. Brains remember even when memory forgets.

Hearing and the brain

Yet the same cannot be said for the actual act of hearing. When it comes to hearing, the ears and brain must work in tandem for optimum results, in the same way that an impressive set of muscles depends on a mental commitment to continuing to work out and eat healthily. Although ears transmit the sounds, it is the brain that process these into coherent messages; it’s for this reason that hearing loss, if left untreated, can contribute to cognitive difficulties. Just as in the example of exercising for a strong physique, the hearing ‘muscle’ can become flabby and weak with disuse, making it more difficult to reinstate the ear-to-brain pathways once help is, eventually, sought. Additionally, the brain shrinkage that is associated with the normal ageing process is accelerated in those with reduced hearing capacity.

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Since hearing is so emotive, one of the dangers in losing the ability to hear comfortably is losing that ability to experience the emotional reaction that hearing memory-triggering or dopamine-releasing sounds can evoke. Listening to an opera can fail to open those oddly satisfying and cathartic floodgates of tears. A walk in the woods, unenhanced by the susurrations of trees, the crackle of leaves underfoot, the scampering of wildlife, may be disconcerting rather than calming. The voices of loved ones may seem indistinct. Faced with the difficulties of listening, people with hearing problems often retreat further, alienating themselves from friends and family, losing connection not only with their own emotional triggers but also with the support and companionship of loved ones.

Hearing and the brain, both in its sensory processing function and memory storing function, are inextricably linked; the loss or impairment of either can be incredibly disorienting and isolating. While there are some sounds that must inevitably be lost over time - the roar of a Tyrannosaurus, the static dial-in of a modem - there are others deeply rooted in our emotional pathways, whether by way of personal experience or vibrational energy. Recognising and responding to these is vital to our emotional well being, if we are healthy, and could be critical in our recovery or reconnection, if we are not.

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