This feature is part of Music and Your Mind, a series exploring how music affects your brain. Read part 1 on behavior and part 3 on torture.
(CNN)"People told me, 'You are changing me.' 'You are healing me,' " Emma Smith said.
This is the feedback Smith receives on her YouTube videos, which compile gentle sounds created by touching, tapping or stroking objects, such as hairbrushes and books.
These sounds can create an autonomous sensory meridian response, or ASMR. This is a tingling sensation, usually starting in the crown of the head and moving to other parts of the body.
"Everyday objects all have a sound," Smith said.
The experience is caused by a range of "triggers," including whispering, soft speaking, tapping, scratching, slow hand movements and close personal attention, reports one of the few studies into this phenomenon.
Not everyone experiences ASMR. Smith believes it comes down to an individuals' sensitivity to sound.
But the experience was linked to a reduced heart rate and increased skin conductance levels, offering potentially therapeutic options for mental and physical health, according to a 2018 report. Another study has shown that ASMR videos can temporarily ease symptoms of depression or chronic pain in listeners.
The experience is about "noticing things around you" and helping people become present, she said.
As someone who was diagnosed with post-traumatic stress disorder in 2013, Smith turned to YouTube in search of relaxation videos herself to help her sleep and feel at ease. "If I was able to sleep and be calm, I was able to focus on my therapy," she said.
Today, Smith helps more than 670,000 video channel subscribers relax, sleep and handle pain or stress by using everyday objects to create ASMR-inducing sounds.
Smith creates ASMR (Autonomous Sensory Meridian Response) videos, she taps and strokes everyday objects, like a hairbrush, to create gentle sounds that can help listeners sleep, relax or concentrate.
A form of mindfulness
The exact nature of ASMR is not understood, according to a report by Swansea University, in the UK. One theory is that the tingles some people experience result from a minor seizure, but this has not been investigated.
The Swansea report found that participants who had depression used ASMR videos specifically to help them with their condition. ASMR can improve mood in depressed people because it can be considered as a form of mindfulness, according to the researchers.
People focus on the positive feelings created and focus exclusively on the present task, explain the researchers. This is similar to other mindfulness practices, like meditation, that have been shown to improve depression and chronic pain.
ASMR also helps people rest, sleep, study or focus better, Smith said. A state of pure relaxation helps people function well, she says.
Tones to relax with
Sleeplessness and insomnia is a global problem. A recent study found that people who get an average of only six hours sleep per night had a 13% higher mortality risk compared to people who enjoyed seven to nine hours. 2014 CDC figures revealed that over one third of Americans struggle to get enough sleep regularly.
It is therefore not surprising that people are searching for means to relax and help them sleep.
When it comes to healing or providing calm, lighter tones are usually beneficial for relaxing the head area, while deeper tones usually relax the body's bones, said Smith who now runs sound therapy sessions that involve people lying down and listening to chanting, gongs or other instrumental sounds.
Smith uses singing bowls to create relaxing sounds during sound bath sessions.
After a sess