Like many people when they’re driving to the market or to pick up the kids, Courtney Biddle will click on the radio and hope for a good song.

These days, Biddle will turn up the volume when she hears something folky — say The Civil Wars or Mumford and Sons.

But unlike the rest of us, Biddle doesn’t sing along — she starts to work.

Biddle is a music therapist and that song she hears could help her make a difference in someone’s life, who might have autism or suffered a stroke.

“It’s not recreational for me,” she said. “I’ll hear a harmony and I’ll say to myself, ‘That’s the harmony I’ve been working on with a client’.”

Biddle is the owner of Progressions Music Therapy Services, which she operates out of an office in Stonington, though she often travels with a guitar and an array of percussion instruments to meet with her clients and patients.

Music therapy has its origins in 18th century medicine and has grown to be a successful course of treatment for a variety of physical and mental ailments, from Parkinson’s disease to depression.

“We address all of those domains,” Biddle said. “It’s not just physical, it’s a biological, psychological and social approach…so with music we can adapt so even the most compromised person can be successful in music therapy. “

Research has shown that music therapy can cause the brain to release increased levels of dopamine, but also help in the recovery of motor and verbal skills.

The field was in the headlines in recent years after former Arizona Rep. Gabrielle Giffords used music therapy to help regain her speech functions after she was shot in head during an assassination attempt in 2011.

According to American Music Therapy Association, there more than 5,000 certified music therapists in the country. The organization’s website, though, urges potential clients to discern between a helpful musician and licensed practitioner.

And its certification process is hardly an easy tune to learn. Music therapists must earn both bachelor’s and master’s degrees in the field, then undergo 1,200 hours of training to attain certification. Every five years, therapists complete

additional courses in professional development.

Biddle, who first wanted to enter music education, earned her bachelor’s degree in music therapy from Wooster College in Ohio and a master’s degree in music therapy from Temple University in Philadelphia

An Ohio native, Biddle grew up in a musical household. Her chosen instrument was a bit unconventional for a child.

“I think I was the only person under 80 in my classes,” she joked about learning to play the organ.

In sessions, Biddle usually brings a guitar and drums, though certified music therapists must also prove competency on piano and voice.

But as the human capacity to appreciate and respond to music is fairly universal, no one needs musical ability or training to benefit from therapy, Biddle explained.

“You don’t have to be musical,” she said. “It’s not a requirement.”

After an initial assessment, Biddle will try different approaches. Sometimes she will play a tune herself or other times she and her clients will improvise together and make up songs.

With some of her younger clients, she has co-authored fun songs that reinforce positive behavior, such as “Don’t Spit On the Bus” or “Wash Your Hands”.

Biddle also works with recovering alcoholics and drug addicts at rehabilitation centers around the region.

There, she will often play songs that convey messages of hope and promise, such as “Affirmation” by 90s duo Savage Garden and explore the lyrics, their meaning and particular relevance to the lives of those participating.

“In some cases we’ll make up new lyrics to have (clients) say what they need to say to themselves,” Biddle said.

Music, Biddle said, can reach people and help them engage with the world in a way that might be difficult in conventional ways. Biddle said that clients turn to music therapy often as a last resort and relayed a remark from a parent of a child with autism — ‘My child doesn’t speak, but they sing with you.’

“I love what I do,” Biddle said, “and I think the main reason is that I get to see progress every day. I see the way music works in our brains and our bodies. Children who may have one- or two-word utterances are able to sing a phrase or an entire song and this will often translate into their daily life,” she explained.

“These things that are real miracles for these families — I get to see it all the time.”