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  • Arriving home after a long day, you settle in for a quiet evening alone.

  • But instead of the sound of silence, you hear a constant ringingeven though there's nothing making any noise.

  • What you're experiencing is called tinnitus, the perception of a noise like ringing, buzzing, hissing or clicking that occurs without any external source of sound.

  • Tinnitus has been bothering humanity since Ancient Babylon, plaguing everyone from Leonardo da Vinci to Charles Darwin.

  • Today, roughly one in seven people worldwide experiences this auditory sensation.

  • So where does this persistent sound come from?

  • When you normally hear something, sound waves hit various areas of your ear, creating vibrations that displace fluid inside the cochlea.

  • If the vibrations are large enough, they elicit a chemical response that transforms them into bioelectrical signals.

  • These nerve impulses are then relayed through the hearing pathway to the brain, where they result in the sounds we perceive.

  • However, in the vast majority of tinnitus cases, the nerve signals that produce these mysterious sounds don't travel through your ear at all.

  • Instead, they're generated internally, by your own central nervous system.

  • Under usual circumstances, these self-produced signals are an essential part of hearing.

  • All mammals demonstrate on-going neural activity throughout their hearing pathways.

  • When there are no sounds present, this activity is at a baseline that establishes your neural code for silence.

  • When a sound does appear, this activity changes, allowing the brain to distinguish between silence and sound.

  • But the auditory system's health can affect this background signal.

  • Loud noises, diseases, toxins, and even natural aging can damage your cochlear cells.

  • Some of these may heal in a matter of hours.

  • However, if enough cells die, either over time or all at once, the auditory system becomes less sensitive.

  • With fewer cochlear cells relaying information, incoming sounds generate weaker nerve signals.

  • And many environmental sounds can be lost completely.

  • To compensate, your brain devotes more energy to monitoring the hearing pathway.

  • Just like you might adjust the knobs of a radio, the brain modifies neural activity while also tweaking the tuning knob to get a clearer signal.

  • Increasing this background neural activity is intended to help you process weak auditory inputs.

  • But it can also modify your baseline for silencesuch that a lack of sound no longer sounds silent at all.

  • This is called subjective tinnitus, and it accounts for the vast majority of tinnitus cases.

  • Subjective tinnitus is a symptom associated with practically every known ear disorder, but it isn't necessarily a bad thing.

  • While its appearance can be surprising, subjective tinnitus has no inherently negative consequences.

  • But for some, tinnitus episodes can trigger traumatic memories or otherwise distressing feelings, which increase the sound's intrusiveness.

  • This psychological loop often leads to what's known as "bothersome tinnitus," a condition that can exacerbate the symptoms of PTSD, insomnia, anxiety, and depression.

  • There's no known cure for subjective tinnitus.

  • So the most important thing doctors can do is help people understand this auditory event, and develop neutral associations with these often-distressing sounds.

  • For example, sound therapy uses noises like rain, birdsong, or music to mask tinnitus and reduce stress.

  • One form, called informational masking, uses soothing, complex auditory signals that distract the brain from the tinnitus sound.

  • Another, called energetic masking, uses sounds with the same frequency as the patient's tinnitus to occupy the neurons that would otherwise deliver the tinnitus signal.

  • Practiced alongside counseling, these interventions allow people to re-evaluate their relationship with tinnitus.

  • Losing the sound of silence can be troubling to say the least.

  • Tinnitus reveals that your brain is constantly analyzing the world around you, even as it fails to filter its own internal noise.

  • In a sense, experiencing tinnitus is like eavesdropping on your brain talking to itselfthough it may not be a conversation you want to hear.

  • As mentioned in this video, tinnitus can be particularly difficult for those struggling with PTSD, but what exactly is this disorder?

  • And what steps can be taken to help those suffering from it?

  • Learn more with this video, or check out this video for advice on coping with insomnia.

Arriving home after a long day, you settle in for a quiet evening alone.

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B2 US TED-Ed auditory sound subjective silence neural

What’s that ringing in your ears? - Marc Fagelson

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    Celine Chien posted on 2020/10/20
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