Why Your Brain Loves Music4
Hertz So Good!
June 27, 2015
Sound is just a ripple in the air that moves your ear drum.
If you like big words, then… Ahem: sound is wave motion propagated in an elastic medium, travelling both transversely and longitudinally.
Those ripples are like waves in the ocean, and the space between individual waves is called a ‘CYCLE’.
Another name for a cycle, or a single complete vibration, is WAVELENGTH.
Think about the length of a wave, as the distance sound travels, during a period of time.
The term PERIOD is used to define the time it takes, for an individual wave to complete its cycle.
If we are trying to count the number of waves over any time span, we are trying to determine the FREQUENCY.
The time span we normally use is 1 second, when calculating the frequency of sound waves.
Relationships exist between these terms, allowing us to apply mathematical models, and make predictions.
Measurements have taught us that the higher the frequency of waves, the shorter the wavelengths.
This may be hard to picture in your head, so let’s use the piano as a bit of a guide.
Sounds on the LEFT side of the piano (lower notes) have longer wavelengths, but smaller frequencies. The opposite is true when you press keys on the RIGHT side, where the ‘higher’ notes reside.
When you hear a very ‘high’ sound, from right sided keyboard notes, or someone screaming, your tympanic membrane is being vibrated very quickly (high frequency), by short wavelengths (sounds that are not All About That Bass).
If we listened to a tone that escalated from low notes to high notes, the frequency of waves would increase, resulting in us hearing a change in OCTAVES.
When nerds discuss this stuff, they use a short cut, using a measurement referred to as HERTZ (Hz).
Here’s what Wikipedia had to say about this, along with the Hyperlinks…
“The hertz (symbol Hz) is the unit of frequency in the International System of Units (SI) and is defined as the number of cycle(s) per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves. One of the unit’s most common uses is in the description of sine waves and musical tones, particularly those used in radio and other audio-related applications. It is also used to describe the speeds at which computers and other electronics are driven”.
(If you actually go to Wikipedia, you will see that I corrected a small typo when I published this passage on my blog. If you feel like checking that out, let me know in the comments section if you found the mistake I am referring to)
So, HERTZ are units of sound, used to measure the number of waves in 1 second.
If you were at the beach watching the ocean, you may see individual waves passing the same spot at roughly 1 per second.
You could impress your nerdy friends at the next party, and tell them that you watched water travel at 1 Hertz.
Again, you could switch the words around a bit, and say the waves traveled, at 1 cycle per second, or the wavelength’s period was 1 second.
HERTZ = NUMBER OF WAVES / 1 SECOND
Therefore 100 Hz = 100 waves (or cycles) per second.
If you were trying to calculate the speed of sound, close to the end of the nerd party (930pm), during math drinking games, you would use the following equation:
SPEED OF WAVE = WAVELENGTH X FREQUENCY
The speed at which sound waves travel, is about 344 metres per second (344m/s).
Sound waves are much smaller than liquid waves, are invisible, and travel through the air.
With much less resistance, sound waves can travel much more quickly, compared to water.
Humans can’t hear every sound. All the sounds that we have measured, exist between 0, to over 1,000,000 waves per second.
Humans can hear sound waves in ranges between 20 to 20,000 Hz.
Other animals have different ranges, as you can see, in the chart below.
Now that we have discussed the concept of Hertz, let’s get to some really cool stuff.
There is a magical phenomenon that occurs in the brain, when it is exposed to BINAURAL TONES.
Binaural Tones, or Beats, were discovered in 1839 by Heinrich Wilhelm Dove, but became more than mere curiosity, when Gerald Osler published his paper; ‘Auditory beats in the brain’ in 1973.
A Binaural Tone occurs when each ear listens to frequencies that differ by 10-30 Hz.
For example, if you are wearing stereo headphones, and you listen to pure sine wave tones of 320 Hz in one ear, and 340 Hz in the other, there is the possibility of magic.
The difference between these 2 frequencies is 20 Hz, and due to an effect called the ‘Frequency Following Response’, the brain stem creates a 3rd sound; the ‘Binaural Beat’, at this new frequency (20Hz).
Now an even cooler thing happens, if the Binaural Beat is thumpin’ at a frequency that is relatively close, to the rhythm of our own brain waves.
Most of our brain waves are travelling at a rate somewhere between 1-50 Hz.
If our brain creates a Binaural Beat, due to external tones, close to the frequency of the rest of the brain, there is a good chance the brain can become hypnotized through a process called ENTRAINMENT.
During Entrainment, our brain waves actually change their own frequency, to match the Binaural Beat.
This process synchronizes the brain’s and body’s movements, and can induce changes in our state of mind.
It is like our neuronal lemmings become entranced by a seductive Pied Piper, leading our mind on a Journey of its choosing.
Sometimes, listening to these pure sine waves can feel too intense; in that case you can mix these tones with background PINK! noise, a variant of WHITE noise.
Binaural Beats were first used to help diagnose neurological disorders, due to the fact that physiologically, these beats are processed by very specific parts of the brain.
If one of these areas of the brain are not working properly, the individual is not able to hear Binaural Beats, even if Dr. Dre is prescribing them.
In cases of both stroke (producing aphasia), and Parkinson’s Disease, the person is unable to catch THIS SICK BEAT ™, but the ability returns once the person’s illness improves.
Binaural Beats have been studied, to correlate frequencies of brain waves, with states of mind; ultimately to determine which ones Hertz So Good.
An example would be inducing one’s brain waves to oscillate between 7-13 Hz (Alpha waves), causing a perception of relaxation and comfort in the mind, or at 7 Hz to help induce meditation.
They can also have deleterious effects on mind control; at 15 Hz, it is apparently almost impossible to meditate.
Binaural Beats have been also been studied in: pain control, improving communication between the brain’s hemispheres, and to increase endorphin and dopamine release.
Unsubstantiated claims about Binaural Beats include: enhanced creativity, simulation of the effect of illicit drugs, improving memory and learning, recovery of repressed (and sometimes false) memories, induction of lucid dreaming, helping with smoking cessation and sticking to a diet, and that it may improve erectile dysfunction, and athletic performance,
likely in that order.
Here is an example of Binaural Beats, in the Theta wave range (4-7 Hz) used for deep relaxation. You do not require headphones. The visual effects are also pretty trippy 🙂
While we can’t hear sound waves at every frequency, we can hear quite a few interesting things within our narrow band of human awareness.
Tune in next time, to learn how music spreads like Ebola inside your skull, as it captures more and more of the brain’s attention, in WTBLM5- Dominoes Dancing.
Simon Trepel, MD
Note 1- if those beats were not to your liking, this mix may have the same effect.
Note 2– For Binaural Beats to appear, the source frequencies must be under 1000 Hz, and the difference between them must be > 10 but < 30 Hz, or else no sound synergy occurs.
At differences greater than 30 Hz, the brain is able to separate the tones, as they actually exist in nature, and selectively attend to only one at a time, called ‘The Cocktail Party Effect’.
Note 3– Binaural Beats are also possible using speakers instead of headphones, and are not merely a phenomenon of sound. A similar process can happen by exposing the visual system to certain frequencies of light. Check out the Dreamachine…
Note 4– here is a list of typical examples of sounds with corresponding frequency ranges displayed in units of Hertz. BW is short hand for Brain Waves.
4 Hz or less– Delta Waves (BW)
Deep dreamless sleep, loss of body awareness
4-7 Hz– Theta Waves (BW)
Deep meditative relaxation, Non REM
7-13 Hz– Alpha Waves (BW)
Relaxation while awake, drowsiness just before and after sleep, dreams
The low rumbling of a passing train in the distance
The lowest note on a piano
13-39 Hz– Beta Waves (BW)
Activity, business, anxiety, concentration, arousal, thinking, vigilance, and paranoia
40-45 Hz– Gamma Waves (BW)
Higher mental activities- perceptions, problem solving, fear and consciousness
The hum of fluorescent lights
Average male speaking voice
Average female speaking voice
Mariah Carey’s glass shattering ‘High C’
Actually, the exact number would be 1024 Hz.
You can calculate this easily, by scrolling back up to the chart comparing notes and Hz.
If you look at ‘C’, this specific note occurs, whenever air is vibrated at 32 Hz.
What is even cooler is that at every multiple of 32 Hz, the note ‘C’ occurs again, albeit in a HIGHER OCTAVE.
The lowest ‘C’ note that exists, is at 32 Hz.
We have to climb up 5 octaves, to hit the glass shattering note.
Objects that shatter must have a high inherent vibration frequency, such as a crystal wine glass. When a note, or tone, causes the atoms in the glass to vibrate at their own natural frequency, the cohesion between the atoms is lost, and the glass vibrates itself into shards.
Range of a majority of the notes that create a sense of pitch
This range is the most important for hearing music. Over time, the hair follicles of the inner ear stiffen, an ironic erectile dysfunction for men, reducing hearing by as much as 5000 Hz on the end of the higher notes.
Luckily, still being able to hear from 20 Hz, all the way to 15,000 Hz, is good enough to hear all of the strongest notes that create pitch
The highest notes on the piano
Over 6000 Hz
Still audible to humans, but sounds like high pitched whistling
For more info on Brain Waves, check out the following link:
Thanks for reading all the way to the lowest notes!
Simon Trepel, MD
Simon Trepel, MD FRCPC, is a practicing Child and Adolescent Psychiatrist, in Winnipeg, Canada. He is an Assistant Professor, at the University Of Manitoba, in the Faculty of Medicine, and the Co-founder of the GDAAY Clinic. He is, more importantly, the proud Father of 2 beautiful Daughters. He writes in his spare time about things he knows something about, and occasionally about things he doesn’t; like Yoga, and Italian flavored coffees. He was not referring to coffee that tastes like an Italian person.
Check out his Blog, called Simon Says Psych Stuff, at