Sound’s Effects

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By Mary Carpenter

Much of the inspiration for researching sound’s effects on the body comes from its potential benefits for sleep and for pain and anxiety relief.  While the emotional effects of sound bathing might appear easier to assess than those of the forest, because of the objective measurements of decibel (loudness) and Herz (frequency, or vibration), the supporting evidence is not much more definitive.

Symphonic music’s ability to block pain is among the most measurable effects of sound, seen in mouse studies led by neurobiologist Yuanyuan Liu at the National Institute of Dental and Craniofacial Research.  After researchers artificially interrupted the connection between the auditory cortex and the thalamus, which is the central hub of sensory processing in the brain, the mice appeared numb: when prodded, they didn’t flinch or pull their paws back.

The numbing occurred only when music was played quietly—at around 50 decibels, barely above the sounds of background noise—while at louder levels, the mice’s paws became almost three times as sensitive.  Numbing effects were similar using both pleasant and dissonant symphonic music, as well as white noise—all of which, at these low sound levels, create a sort of buzzing sound. Said Harvard neurobiologist Clifford Woolf, “Many would have anticipated you need to listen to Mozart to get pain relief. But maybe all we need is to give patients a tiny level of buzzing noise.”

Dentophobia or odentophobia —“extreme fear of going to the dentist”—inspired an Indian study of 50 dental patients undergoing tooth extraction. For the 25 patients who listened to music, anxiety levels decreased as did blood pressure and heart rate. But the effects occurred only when the music was familiar —religious music for these patients, whereas classical music caused their levels to rise.

Familiar music, however, “might recall certain pleasant memories associated with the music…and therefore is responsible for the reduced anxiety,” the researchers suggested. (Experts warn that “true phobias, stronger versions of the common fear, require different and sometimes more intensive measures,” such as weighted blankets that apply deep-touch pressure.)

“Welcome to the cult of brown noise” began a recent New York Times article on physiological effects of “immersive” sound frequency combinations found in white, brown and pink noise—that “may help the brain to focus, sleep or relax especially for people with ADHD,” writes Dani Blum. Like white noise but with a lower, deeper quality, brown noise is a “category of neutral, dense sound that contains every frequency our ears can detect” with effects that can be smothering.

“Noise that is just stimulating enough to activate the brain but is not overwhelming” can help block background noise as well as internal chatter, such as worrisome thoughts, according to Blum. Pink noise plays at lower frequencies than white noise but louder; violet noise includes higher frequencies that can make a hissing sound; and gray noise “sounds similar to white noise, but is smoother.” Pink noise in a small study led to deeper sleep—though some researchers trace the effects of these sounds simply to drowning out annoying noise such as traffic. And because the sound combinations can bleed into each other, noted Regis University pharmacy professor Daniel Berlau, “it’s not as scientific as people would think.”

For the most intensive auditory effects, “sound baths” can combine a mix of different instruments “because each gives off different frequencies or vibrations,” according to yoga teacher Christy Maskeroni Price. Small studies suggest health benefits such as lowered heart rate and heart rate variability following sound baths may reflect reduced stress and anxiety—while others suggest “sound baths” are more likely to provide a spiritual experience in contrast to the medical effects of music therapy.

“Solfeggio frequencies” refers to “specific tones of sound that help with and promote various aspects of body and mind health,” according to the BetterSleep blog. “Musically speaking, the frequencies [begin] at 8Hz and working up the musical scale octave by octave until the C note is vibrating at the 256 Hz frequency and the A note is vibrating at 432 Hz.” (The frequency of the highest piano note is above 4000 Hz, while flute sounds are closer to 2100 Hz and most songbirds’ chirping falls between 2000 and 3000 Hz.)

Different solfeggio frequencies played in varying combinations create vibrations that purport to heal specific ills. Frequencies at Apple’s solfeggio site, for example, begin with help for trauma, fear and negative energy at 285 Hz, 396Hz and 417 Hz respectively—with links to listening experiences for each one.

Different people react to sound baths in different ways, however, with feelings that range from especially relaxed to a boost of energy. But compared to virtual sound baths, being in the room with musical instruments offers a more direct experience of the vibrations, according to Price. In-person sound baths are available at centers for alternative health or yoga, as well as at pop-ups listed as they arise.

To experience the sound bath of the Integratron near Joshua Tree National Park, people travel from around the world and reserve months in advance. According to the Integratron site, “sonic sessions” in its wooden dome include a sequence of 20 quartz crystal singing bowls with “each bowl keyed to the energy centers or chakras of the body.”

Because the Integratron has no waiting list, those hoping to snag a place from no-shows arrive early to wander through the surrounding desert garden. Visiting Joshua Tree with a friend, we eventually obtained two passes. But we found it hard to separate effects due to the softly chiming bowls from those of lying on soft mattresses under the beautiful dome—or of having already spent several days on a desert vacation. We did emerge very relaxed—as well as energized for an afternoon desert walk, plus a night of live music in the nearby mountains.

—Mary Carpenter regularly reports on need-to-know topics in health and medicine.