Have you ever used natural sounds to help you fall asleep, listened to music to help you concentrate when studying, or felt agitated when hearing thunder? This is due to sound frequencies.

Whether we are aware of it or not, sound frequencies have a powerful  and constant effect on both our bodies and minds. In this article, we will be looking at how sound frequencies affect us. 

What sound frequencies are:

Sound is a vibration. What determines a sound's frequency is the number of vibrations that a sound wave completes in a second. It is measured in Hertz (Hz). Humans can detect sounds in a frequency range of about 20Hz to 20kHz, but some lose high-frequency sensitivity with age.   Lower frequencies are linked to lower-pitched sounds (a drum) whereas higher frequencies are linked to higher-pitched sounds (a whistle.) 

In summary: Every sound has a frequency, which defines how fast the sound waves are vibrating.

Different forms of brainwave frequencies

Each brain wave frequency is a reflection of the state your body is in. Your brainwave frequency will be different when you are relaxing, falling asleep, in deep sleep or awake. However, brainwaves can be altered by various external stimuli. Auditory stimuli and especially music are among the most interesting.

There are 5 brainwave frequencies:

• Delta waves

• Theta waves

• Alpha waves 

• Beta waves 

• Gamma waves 

- Delta waves (0,5 to 4 Hz) are active during deep sleep, a phase before and after REM sleep.  They are associated with the body’s recovery stage in which new cells are produced.  Primary functions: Physical healing, immune regulation, growth and recovery. 

- Theta waves (4 to 8 Hz) are present when you are creative or during REM sleep, the phase of sleep where you dream. Primary functions: Memory consolidation and emotional processing

- Alpha waves (8 to 14 Hz) are common when someone is awake yet peaceful i.e daydreaming. Primary functions: Stress reduction and learning readiness.  

- Beta waves (14 to 38 Hz) occur when you are active and allow you to concentrate. When there is an excess of these types of waves, you experience stress. Primary functions: Attention, decision making and conscious thinking  

- Gamma waves (38 to 80 Hz) occur during strong mental activities, such as studying and solving problems. They are associated with high-level cognitive functions. Primary functions: Perception, working memory and rapid information processing. 

Emotions and mood

According to a study published in the National Library of Medicine, specific audio frequencies may affect brainwave patterns. Brainwave entrainment is a process that synchronises brainwaves in response to external stimuli, such as sound frequencies, to promote mental states, such as relaxation or attentiveness. Another study that confirmed this, demonstrated that a group of individuals exposed to 6 Hz sounds for 10 minutes presented a significant increase on theta wave (4 -8 Hz) cortical activity in comparison to a control group that did not receive the stimulus. 

The bioelectrical brainwave activity changes while listening to music. Our emotions and mood can be affected because of its emotional impact and frequency combination. Positively resonant music can enhance mood and general well-being, whilst sad or violent music may cause unpleasant emotions for some listeners.

Some researchers indicate that listening to your favorite song releases dopamine, a neurotransmitter associated with pleasure and reward in the brain. Happy music has been associated with a more positive mood, motivation and beneficial physiological responses. 

Lower frequencies correspond to deeper, bass tones which promote relaxation. On the other hand, higher frequencies produce sharper, tremble tones which increase alertness.

Clinical studies on patients diagnosed with mental disorders such as anxiety, depression and schizophrenia have shown a visible improvement in their mental health after general music and music therapy interventions as a primary tool. 

Effects on our bodies

A recent article published by Harvard Medical School shows that music or sound frequencies influence the autonomic nervous system (ANS), which is a network that controls certain involuntary processes like breathing and heart rate. The valence of the music, which signals whether the music feels positive, negative, or somewhere in between, influences the ANS, too. These factors are among the reasons why our heart rate goes up when we hear the infamous music from Jaws, or why heavy metal might make us feel uncomfortable if we’re not used to it.

Because music is often an enjoyable activity, it can activate the release of endorphins, which creates a general feeling of well-being. Music/ sound therapy can significantly alter brain waves changing agitated wave patterns to exceptionally calm wave forms. Thus, they can successfully reduce post-operative pain, physical tension and influence heart and breathing rates. As our brain waves slow down, we shift from an active state to a more relaxed, dreamlike state. Fast music tends to increase pulse rate and blood whereas slow music tends to decrease them. 

Audio Frequencies of Modern Music

There have been debates as to what frequency music should be tuned to help the health of the population. The current reference frequency for tuning musical instruments is 440 Hz. Some theorists and musicians claim that the 432 Hz tuning has better effects on the human body. A study published in the National Library of Medicine, showed that 432 Hz decreases heart rate more so than 440 Hz does. 

As Nikola Tesla once said, “If you want to find the secrets of the universe, think in terms of energy, frequency and vibration.” Hence, it is very encouraging that scientists are looking into the sound frequency field to establish the effects it has on the human body and mind, in everyday life and with the hope to cure neurological problems.