Sound is supposed to be simple. A phone rings, someone speaks, music plays in another room, or a door closes somewhere down the hall. We hear it, recognize it, and move on. But the act of hearing is far more complicated than sound entering our ears. The brain has to separate competing noises, recognize patterns, attach meaning to words, decide what deserves attention, and discard what doesn’t. When something interferes with that process, a perfectly ordinary sound can become confusing, exhausting, overwhelming, or quite possibly, even threatening.
That territory fascinated me while writing my newest novel, Call Waiting. In the novel, Londyn Andrews begins hearing voices when she’s placed on hold. Doctors attempt to explain what is happening to her as auditory processing trauma. In Londyn’s world, that explanation seems almost reasonable. Until the voices begin saying things they shouldn’t possibly know.
Before talking about the fiction, though, I wanted to explore the very real science underneath it. First, an Important Distinction: Auditory processing trauma isn’t an established medical diagnosis. I use the phrase fictionally in Call Waiting because it describes the intersection I wanted to explore: trauma, memory, attention, fear, and the way the brain interprets sound.
There are, however, several very real conditions and phenomena that overlap with this idea. One is Auditory Processing Disorder, often called APD or Central Auditory Processing Disorder. A person with APD may have normal hearing on a standard hearing test but still have difficulty making sense of auditory information. The problem is not necessarily whether the ears can detect the sound. It is what the nervous system does with that sound afterward.
The American Speech-Language-Hearing Association describes central auditory processing as involving the brain’s ability to discriminate sounds, determine where sounds originate, recognize auditory patterns, process timing information, and understand speech when competing or degraded sounds are present.
Trauma introduces another layer. Research involving post-traumatic stress has found differences in sensory and cognitive processing, including heightened responsiveness to threatening or unexpected stimuli, exaggerated startle responses, hypervigilance, difficulty filtering irrelevant information, and altered responses to auditory stimuli. In other words, sometimes the problem isn’t simply: Can I hear this? It can become: What does my brain think this sound means? That question became central to Call Waiting.
How Many People Are Affected? This is where numbers become complicated. Because diagnostic criteria for APD vary considerably, prevalence estimates vary too. Reviews have estimated APD at roughly 0.5–1% of the general population, while some estimates among children fall around 2–5%. Prevalence also appears to increase substantially among older adults, although estimates differ depending upon how auditory processing difficulties are defined and tested.
A 2026 review emphasized an important problem: there’s still considerable disagreement about diagnostic criteria, particularly in children, and APD symptoms can overlap with language disorders, attention difficulties, dyslexia, and other conditions. Adult prevalence is even harder to pin down. Research has produced widely varying estimates, and standardized information for adults younger than sixty remains limited.
There also isn’t a reliable prevalence figure for “trauma-related auditory processing problems” as one unified condition, because that isn’t a single diagnosis. Trauma may instead appear through PTSD symptoms, hypervigilance, sound sensitivity, tinnitus, hyperacusis, concentration problems, or difficulty filtering sensory information. That uncertainty interested me as a novelist. There are experiences people can describe very clearly even when medicine doesn’t have one convenient label that explains them all.
When Does It Begin? Auditory processing difficulties can have different origins. Some appear developmentally during childhood. Others may emerge or become more noticeable later in life. Acquired auditory-processing problems have been associated with neurological illness, aging, and traumatic brain injury.
ASHA notes that auditory problems following traumatic brain injury can include difficulty listening in background noise, maintaining attention, remembering spoken information, and following multistep verbal instructions. Importantly, those symptoms may arise from auditory-processing deficits, broader cognitive effects of brain injury, emotional conditions such as PTSD, or some combination of them.
Psychological trauma presents a different mechanism. Someone with PTSD may become unusually alert to environmental cues associated with danger. A sound that another person barely registers—a slammed door, footsteps, an alarm, a particular tone of voice—may trigger an intense physiological response because the nervous system has learned an association between that sound and threat. Research into PTSD has repeatedly documented exaggerated startle and hypervigilance, including heightened responses to unexpected noises. The ears may be functioning normally, but the brain is simply no longer treating the sound as neutral.
What Can It Feel Like? Auditory-processing difficulties don’t look identical from person to person, but commonly reported problems can include:
* difficulty understanding speech when several people are talking
* trouble following rapid speech
* needing people to repeat themselves
* difficulty following lengthy verbal directions
* struggling to understand conversation in restaurants or other noisy places
* confusing similar sounds or words
* feeling mentally exhausted from listening
* difficulty determining where a sound came from
* remembering only portions of something that was said
APD can exist even when standard hearing thresholds appear normal. Trauma-related auditory reactions can feel different. Hypervigilance may cause someone to continually scan the environment for sound. Unexpected noises may produce an exaggerated startle response. Certain sounds may become emotionally loaded because they are associated with previous experiences.
There are also separate sound-tolerance conditions such as hyperacusis, in which ordinary sounds can seem painfully or intolerably loud; misophonia, involving intense reactions to particular sounds; phonophobia, involving fear of sounds; and broader noise sensitivity. These terms describe different experiences and shouldn’t be treated as interchangeable.
Researchers have even documented persistent sound hypersensitivity following head trauma, accompanied in some patients by concentration problems, memory difficulties, anxiety, and increased sensitivity to stress. That combination—sound, memory, anxiety, interpretation—is precisely the space where fiction began taking over for me.
The Belief That “I’m Hearing Things”: One of the most interesting aspects of auditory perception is how rapidly the brain turns sound into meaning. We don’t experience speech as a collection of frequencies. We experience a person saying something. The brain fills gaps, predicts, filters, compares incoming information with memory, and decides which sound matters and which can disappear into the background. That can create a frightening disconnect when someone knows that they heard something but can’t understand why everyone else seems to have experienced the same environment differently.
It is important, however, not to equate auditory-processing problems with hallucinations. APD concerns difficulty processing actual auditory information. Hallucinations involve perceiving sound without a corresponding external auditory stimulus. Trauma responses, tinnitus, hearing disorders, neurological conditions, medication effects, sleep deprivation, and psychiatric conditions can produce very different auditory experiences, which is why unexplained symptoms deserve proper medical evaluation rather than self-diagnosis. But as a novelist, I became interested in the terrifying question between those categories: What happens when someone can no longer determine which explanation fits?
Can Trauma Change the Way We Listen? Research increasingly suggests that stress can influence auditory perception. A 2026 review examining acute and chronic stress described evidence that stress can influence auditory processing through multiple neural mechanisms, including interactions involving auditory networks and brain regions involved in emotion and threat detection. The authors emphasized that chronic stress may produce longer-lasting changes in auditory coding and perception.
Research on PTSD has likewise found abnormalities in attention to auditory information and in the brain’s response to both trauma-related and neutral sounds. This doesn’t mean trauma routinely causes people to hear nonexistent voices. It means something subtler and perhaps more fascinating. Trauma can change what the brain notices, ignores, labels as dangerous, and how strongly it reacts.
How Are Auditory Processing Problems Treated? There’s no single treatment because there’s no single presentation. For diagnosed APD, ASHA describes three broad management approaches that are frequently used together: modifying the listening environment, directly training specific auditory skills, and teaching compensatory strategies that help a person recover information they may have missed. That might mean reducing competing background noise, improving the quality of the auditory signal, using visual information along with spoken instructions, requesting repetition or clarification, strengthening memory and attention strategies, or undertaking individualized auditory training. Treatment should be tailored to the person’s specific deficits rather than assuming everyone with listening difficulties needs the same intervention.
When trauma or PTSD is contributing to sensory hyperarousal, treatment targets the trauma itself rather than treating the experience simply as an auditory disorder. The VA/DoD clinical guidelines identify Cognitive Processing Therapy, Prolonged Exposure, and EMDR among the trauma-focused psychotherapies with the strongest research support for PTSD.
Someone experiencing new or unexplained changes in hearing, speech comprehension, sound tolerance, memory, or auditory perception should begin with a qualified healthcare professional. Depending on the symptoms, evaluation may involve an audiologist as well as neurological, psychological, speech-language, or other specialists.
And Then There Is Call Waiting. This is where I allowed reality to open the door for fiction. Londyn Andrews doesn’t hear the voices during ordinary conversation. She hears them when she’s on hold. That strange suspended place between dialing and speaking, connection and disconnection, and someone being there and no one answering.
At first, there are explanations: stress, trauma, and an auditory-processing problem. Something her brain is constructing from fragments of sound. Londyn wants to believe those explanations because they belong to a world she understands. Then the voices become specific. They belong to people in hospital rooms, accident scenes, motel bathrooms, near bridges and dark water, which are all instances where people may be suspended somewhere between life and death.
And eventually the impossible becomes personal. Londyn’s estranged mother, Georgia Bickford, enters hospice. While Londyn is waiting on another call, she hears a voice she knows immediately. Her own. Not the woman she is now. The girl she used to be. And that younger version of Londyn gives her a warning: Get the truth before your mother dies.
Suddenly, Call Waiting becomes about much more than mysterious voices. It’s about the things families refuse to say. The memories we reinterpret in order to survive them. The way childhood experiences can remain buried until some tiny sensory detail—a voice, a ring, a click, a few seconds of silence—brings everything rushing back. And the terrifying possibility that sometimes what we dismiss as noise contains the thing we’ve spent our entire lives trying not to hear.
The Brain Is Always Listening. The real science of auditory processing is fascinating precisely because hearing isn’t passive. Our brains constantly sort, prioritize, predict, interpret, and connect sound with memory. Trauma can complicate that process. Neurological conditions can complicate it. Attention can complicate it. Age, injury, stress, environment, and emotion can all influence the experience of listening.
The forthcoming fiction novel Call Waiting takes that reality and pushes it beyond the boundary of what science can explain. Because Londyn’s greatest problem isn’t that she hears voices. It is that eventually she has to decide whether they are symptoms or witnesses. And whether the one voice she has spent her whole life avoiding belongs to her mother, the dead, or herself.
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