Segment One

SEGMENT ONE:
THE BASIC PHYSICS OF SOUND

This segment is a first step to take for those who consider the powerful tool of sound as a therapeutic modality. It contains the necessary knowledge for working with such aspects as: frequencies, pitch, loudness, resonance, harmonics, cymatics, etc.

This segment is designed for beginning level and advanced level sound workers.

The sound worker will be provided with articles written in a very simple, straight forward format. In addition to the written material, this segment also includes diagrams, dynamic drawings (GIFs) and tutorial videos.

Segment One Topics:

Definition of sound.
Vibration, medium and receiver.
The frequency and pitch in sound.
Low and high frequencies, wavelength.
Definition of loudness.
How sound travels in a medium.
Review of human perception of sound amplitude.
Review of low and high frequency perception at different volume.
Definition of resonance and resonant frequencies.
Sympathetic resonance.
Discussion about using sound frequencies in medicine and healing.
Debunking common myths about resonant frequencies for healing.
What sound consists of.
Definition of timbre and sound partials.
The difference between harmonics and overtones.
Standing waves.
Definition of constructive and destructive waves (amplification and cancellation of sound).
Nodes and antinodes.
Introduction to cymatics.
Relationship between physical properties of matter and geometrical patterns in cymatics.
What is noise.
The difference between white noise, pink noise and brown noise.
Test to check your knowledge

...and a lot more practical information and insights that the sound worker will need for becoming a skillful artist.

Table of contents:

1a Sound as a physical phenomenon
1b Frequency
1c Loudness
1d Resonance and resonant frequencies
1e Sound partials (overtones and harmonics)
1f Standing waves
1g Cymatics

BONUS
White noise
Pink noise
Brown noise

1a. Sound as a physical phenomenon

Any physical object in motion creates vibrations. Vibrations though aren't the function only of moving objects. At the atomic level there is a constant vibration of everything around and within us.

The term “sound” is applied to vibrations that typically propagate as an audible waves of pressure, transmitted through a medium, such as gas, liquid or solid.

In human physiology and psychology, sound is the reception and perception of such waves conducted by the hearing organs, bones and skin.

Any sound vibration pulsates between the two poles of its maximum and minimum amplitude.
Any repetitive vibration passes through a stage of stillness between new cycles of motion.

In physics, no wave, such as a sound wave, would be possible without movement.

No movement would be possible without space and time.
Sound waves are a physical phenomenon of carrying and transferring energy and information from one source to another.

Sound is the primary language of the universe. Sound is the cause and the effect programmed by nature at the inception of any new vibration. Sound is a continuous revelation of creation.

With all that being said, it’s important to remember that one must be physically present within the medium through which sound vibration is transmitted in order for that sound to be heard. It is one’s conscious awareness that perceives vibrations as the phenomenon that we call sound!

"If a tree falls in a forest and no one is around to hear it, does it make a sound?”

Sound is vibration, transmitted to our senses through the mechanism of the ear, and recognized as sound only at our nerve centers. The falling of a tree or any other disturbance will produce a vibration in the air. If there are no ears to hear, there is no sound.

*Knowing the basic physics of sound empowers one to use sound in the context of healing with clarity, direction, and confidence.
Thomas Orr Anderson

1b. Frequency

A vibration that recurring at regular intervals has its own "frequency". Frequency indicates how FREQUENT the cycle of motion is happening within a fixed unit of time. Vibration with no periodic activity has no frequency.

The measuring units of frequency are Hertz (Hz). One Hertz equals one full cycle per second. For example, when a honey bee makes one full motion of its wings in one second, the frequency of this movement is 1Hz. If the same bee would swing its wings 230 times per second, that means it raised the frequency from 1Hz to 230Hz. Luckily for the bee, along with increasing the vibrations, it would also raise itself up in the air!

Click here to experience the sound of accelerating frequencies.

Sound is a form of vibrational energy that needs to meet a few conditions in order to occur. The first condition is the presence of a medium through which mechanical vibrations could pass (gases, liquids, solids, and plasma). Also, for human hearing, the sound is determined as a very specific range of vibrations. The motion of physical matter starts to be audible when its frequency is higher than 20Hz. Vibrations with fewer than 20 cycles per second are called "infrasound". Infrasound isn't audible, although, if the impulse is strong enough, it can create a physical sensation, such as tickling.

The human ear can register up to 16000 – 20000 vibrations per second. Frequencies above the hearing range are called "ultrasound". The ultrasound isn't audible, but could affect the hearing and physical tissue.

It is a fact that all sounds are affecting our physical tissue. In other words, we hear with the whole body. Pressure waves created by the vibrating matter are being partially reflected and absorbed by our bodies.

Click here to see the bouncing molecules of air.

*The sinuous wave on this diagram indicates pressure waves propagated by sound. The higher the frequency, the denser is the wave.

* The dynamic diagram above shows the distribution of sound. The molecules of the medium are being compressed and expanded with every passing wave.

1c Loudness

Another aspect of sound is the intensity with which audible vibrations are being delivered, which is called loudness. The intensity of sound is a subjective perception of sound pressure.

Sound travels in the medium in a form of spherical waves. The particles of the medium are not traveling with the sonic waves. The molecules of the medium are being systematically compressed and expanded by the mechanical motion of the vibrating source. The compression and expansion event of the molecules of the medium is repeating itself with each passing wave.

In our daily life, air is the most common medium of sound. Vibrating objects are passing energy through the air. The faster the vibration is, the denser are the waves, and, accordingly, the higher the pitch.
The more "forceful" are these waves, the higher is the amplitude (loudness) of sound.

Loudness is a function of the medium (air) pressure over our hearing organs. Through the medium, sound waves are reaching the ear canal and meeting the eardrum. The eardrum transfers the vibrations through the middle ear bones (ossicles) into the inner ear (cochlea). There are thousands of tiny hair cells in the cochlea. They transform the vibrations into electrical signals that are sent to the brain through the auditory nerve. That's how our brain recognizes the audio signals.

The units of measuring sound amplitude (intensity, loudness) are called Decibels (dB). Decibels are an expression of the relative loudness of sounds in a medium as perceived through the human ear.

The threshold of human hearing is 0dB.

The higher the volume, the more pressure on the eardrum is being applied. For your reference, the sound of breath is about 10dB. 20dB would be an average measure of a whisper. 50dB is approximately the volume of a regular conversation.

Volume above 75dB could be irritating, and when it goes above 130dB, it could permanently damage your hearing.

Decibels follow the base ten logarithm scale (80 dB is ten times louder than 70 dB).

Our sensitivity significantly varies over the audible range. For example, a 50 Hz sound must be approximately 43 dB before it is perceived to be as loud as a 4,000 Hz sound at 2 dB. (4,000 Hz is the approximate frequency of greatest sensitivity for human ear with no hearing loss.) So, the 50Hz sound has to have 13,000 times the actual intensity of the 4,000 Hz sound in order to have the same perceived intensity!