A Guide to Sound
In our Guide to Sound, we will look at the basics of the characteristics of sound, how it works, how sound can affect you and some alarming discoveries and also how sound may benefit you with possible musical therapy and it’s use in the medical environment. There is a lot of ground to cover in sound and we will update this with any defining literature we discover.
We aim to give you a little background of sound as a taster before you move into the Guides to Soundproofing as a way of hopefully explaining the terms we often use.
Peace, Quiet and Productivity
In this guide, iKoustic want to give you an overall knowledge of sound – to help give you some context of how sound works, how it could affect you and what you can do about it, and how sound may benefit us. The title, Peace, Quiet and Productivity helps fit nicely with our Mission Statement – Creating Quieter Spaces Together, it is our mission to put you in the sonic driving seat and tackle these issues with us head on.
We, as humans, naturally seek a space where we can feel at home, or at comfort in where we have a high level of privacy to conduct our daily lives and to be able work without little to no interference.
As movement of businesses and homes are now more city orientated than ever, we see buildings of multiple occupancy, so for example a building may have; a gym, shop, bar as well as homes all together – it is important to make sure guidelines and recommendations are followed, and the best soundproofing solutions are installed to tackle them.
What is Sound?
In ‘What is Sound?’, we want to give you the knowledge to help understand sound on a basic level, to help explain some of the content on our website and give it some context.
Sound is an energy that moves in the form of vibration, both through solid and airborne mediums and can be high influenced by temperature, humidity, wind direction and density of the medium it’s travelling through (highly important for soundproofing).
Sound excites our sensation of hearing, these sound waves meet our ear drum and it is then processed throughout the auditory system and reproduced as the sounds we hear.
Decibel (dB)
Decibel (dB) is a measurement that was first implemented and used in the early 20th century to measure the ratio of two powers, or a quality that is related to the power; Sound Intensity as an example. dB is named in honour of Alexander Graham Bell (bel) of Bell System in the United States. The importance of this measurement and formula gave acousticians a baseline to measure sound and is to this day, is the standard.
It’s measurement is based on a logarithmic scale, not linear “A logarithm is the power to which a number must be raised in order to get some other number “ – this is because we hear sounds in such a large magnitude, on a dB scale this is often referred to as Sound Intensity. Sound Loudness (measured in phons) is closely related, although not identical to Sound Intensity, we would use a Loudness scale more often to give more relatability to sound. A common expression is that a 10dB increase in Sound Pressure Level is a doubling of the perceived loudness, 50% louder, inversely, a 10dB decrease in Sound Pressure Level is halving the perceived loudness – a 50% reduction in sound transmission.
You will see this come up time and again in the world of soundproofing.
Below you will find an infographic, highlighting common sounds being generated at that dB level.
Duration
The length of a sound is the measured from the moment it’s conducted to it’s inaudibility (this may be different on digital systems as audibility is subjective)
Frequency
Frequency (measured in Hertz or KHz) is related to Pitch, this means that an increase in Hz would be an increase in pitch, you would say the sound is high pitched at something around 8000hz (8khz) or above. When visualising a sine-wave frequency through an oscillator, you will it’s span between two periods change with frequency. A lower frequency of say 440hz to 1000hz you will see the two periods come closer and closer together, this is how many cycles there are per second (440 cycles per second or 1000 cycles per second for the above frequencies).
Below there are three examples of pitch of low, medium and high frequencies.
Loudness
A subjective measurement of sound, which means this can vary from person to person – some sounds may affect you greatly more than it would for somebody else. This is even more truer to those suffering from hearing impairments such as; hyperacusis, Noise Induced Hearing Disorder (NIHD) or a general aversion to a sound.
You can find more details on help with Hearing Disorders here; https://www.scope.org.uk/support/families/diagnosis/hearing-impairment
Resonance
When an object is excited, it vibrates – and every material object has a resonant frequency of increasing volumes. A great example of this is blowing over the top of a glass bottle – have you tried it? Now try it with a small amount of liquid in it… You will now hear the resonant frequency has changed.
Timbre
This is the character of the sound, it’s tone, colour, resonance or ring – which are ways we may perhaps describe a sound. Two examples would be a metal structure which has an elongated ring, to the thud of a large rock on a grassy field – even without listening to the examples below, if your hearing is intact you can imagine these sounds without conducting them.
What Is Flanking Transmission?
Flanking Transmission or Flanking Sound is when the sound takes an alternative path, other than a single direction. A typical Flanking issue we experience is when a single wall must be treated, but a sound issue is still detected or now more focused in another area adjacent walls, floor and ceiling or through ducting and ventilation.
Take a wall for example, you can see below from the diagram that there are many paths the sound can still travel through. If there is an empty cavity such as a stud wall, or between flooring and ceiling joists – the sound moving into this area will continue to amplify, we will go in to more detail for each specific surface in our ‘Guide To’ series, under ‘A Guide to Flanking Transmission’.
How Could Sound Affect Me?
The research into how sound can affect your health and wellbeing is still early in its development – we still do not fully understand to impact it may have. There are a few key studies and additional literature that highlight noise and its effect on people – but it is a qualitative, subjective measurement and will provoke a different emotion or reaction from person to person. We have drafted some points below to take on board from some of this research. We will aim to keep this guide updated as the studies and science develops.
Sound can be a negative in many peoples lives, we would more likely attribute the word ‘Noise’ to describe sound’s negative effects. Whether the noise consists of roadworks from outside, a dog that barks into the night or even just a conversation next door – we are affected in many ways.
Our ears are always open, this means the equivalent of shutting your eyes to avoid something you dislike is not possible with your ears, some may stick their fingers in their ears to avoid the noise, but most of the sound will still pass this threshold.
A staggering 25% of Europe’s population have suffer from reduced health and quality of life as an effect of noise and noise attributes to the death of 200,000 Europeans a year. Taken from a TED Talk by the ever-informative Julian Treasure on sound.
As we drift from less natural sounds (associated with a calm, peaceful environment such as wind, water and birds) and closer to the noise of automobiles, aircraft, building works, workplace noise and noise at home and other inner-city, urban noises – we put potential stress on our bodies on a very emotional and psychological level.
“Sound pollution can trigger the body’s stress response, one of its major health effects is chronic stress and the high levels of stress hormones that go with it. As a result, noise pollution has also been linked with health problems such as heart disease, high blood pressure, and stroke.”
https://www.verywellmind.com/stress-and-noise-pollution-how-you-may-be-at-risk-3145041
For employers, this can also affect productivity in the work place, we have discussed this in detail on our ‘Workplace Noise and its Effects on Health and Productivity’
How Could Sound Benefit Us?
Sound as a benefit is subjective by that we mean some may see it as a positive, some as a negative, an example of this would be music – although many cherish and love music in a wide range of forms, it is not for everyone and some may even find it irritating.
Here are four areas we are going to look at;
- Music
- Ultrasound
- Lithotripsy
- Sound Healing
Music Therapy
Music is the gateway to structured sound – taking all the properties discussed in ‘Properties of Sound’ and creating a wide range of musical styles with these.
Music Therapy is more and more often referred to as a possible alternative to alleviate certain health issues through less evasive means.
The British Association of Music Therapy aim to;
“Our aims are to promote:
- the art and science of music therapy;
- the use and development of music therapy for children and adults with a wide range of needs;
- understanding of music therapy for the general public
- to advance education in music therapy.”
Sound Healing
An experimental approach to positive health is sound healing, using a range of traditional and modern instruments and technologies.
“Sound therapists believe that our bodies contain ‘energy frequencies’ and that sonic frequencies can be used to reattune these energies when they go off key. All you have to do is lie down and bask in the tuneful beauty of ‘pure’ sound”
This is an excerpt from the Guardian, including both those who believe in the process and sceptical remarks if this is of interest to you.
Traditional Sound Healing
The use of sound healing is not a new-age approach to health and well-being, it has been used for thousands of years across the world with different approaches between societies, tribes and groups with a wide range of instruments that vary in their tone, timbre, pitch and aesthetic.
“The Aboriginal use of the yidaki (or didgeridoo) to heal physical ailments, to the ancient oriental use of the gong for spiritual attunement, music therapy has been used in many cultures and traditions for thousands of years”
Other instruments used in the tradition of sound healing include;
- Dulcimer
- Wind Chimes
- Gong
- Pan Flute
- Singing Bowl
- Hang Drum or Hand Pan
And plenty more.
https://www.theguardian.com/lifeandstyle/2008/jul/06/healthandwellbeing5
Modern Sound Healing
Modern techniques are in line with our recent discoveries of the human brain, how we process certain information, what makes us restless and what areas of the brain are triggered under stressful situations.
We are still a way off fully understanding how the brain works, these are not certainties but worth looking into.
Binaural Beats as an example aims to link in with the different states of the Human Brain Waves which are as follows;
Gamma – 31 – 100hz, Insight, Focus, Expanded Consciousness
Beta – 16 – 30hz, Alertness, Concentration
Alpha 8 – 15hz Relaxation, Visualisation, Creativity
Theta 4 – 7hz Meditation, Intuition, Memory
Delta 0.1 – 3hz Detached Awareness, Healing, Sleep
“Binaural beats cause your brain to synchronize, or entrain, itself with the beat frequency.
This has the effect of inducing a desired brainwave pattern, letting you experience the benefits of that brainwave state at will.“
You can try it here: https://mynoise.net/NoiseMachines/binauralBrainwaveGenerator.php
Mynoise is a great website for looking around at how sound works in relation to these Modern Sound Healing techniques.
Ultrasound
Most will be familiar with experiencing an ultrasound, or to some degree know what it is used for; to monitor an unborn baby or provide guidance to a surgeon during surgery or procedure.
The Ultrasound Probe emits high frequencies that are undetectable by the human ear, creating a moving image that is transferred onto a display monitor.
There are three variations of how an Ultrasound can be used.
External Ultrasound Scan
This is beneficial for monitoring an unborn baby to determine its sex, how healthy it is and possible complications.
It is also used to examine the liver, kidneys and other organs in the abdominal and pelvic areas. Skin, muscle and joints are also monitored.
Internal Ultrasound Scan
This is used primarily for monitoring internally within the prostate, ovaries or womb.
Endoscopic Ultrasound Scan
An endoscope is inserted into your body, most commonly through the mouth to examine your stomach or oesophagus (throat area passage to the stomach)
Lithotripsy
Lithotripsy consists of an ultra-sonic shockwave to pulverise kidney stones to reduce evasive surgery, a great way of using sound to help improve outpatient visits.
