Tag: vibration

Which is more stable, washing machines or birds? The answer might surprise you

What do birds and washing machines have in common? Shockingly, it’s not the ability to wash clothes. Rather, most birds and washing machines are great examples of vibration isolation systems.

Now that’s cool and all – but what is a vibration isolation system?

Better known as a mass-spring-damper system, vibration isolators are generally a mechanical or industrial mechanism that can reduce the amount of vibrational energy produced by a system. Vibration isolators are incredibly important; studies show “undesirable vibrations” can shorten a machine’s service life and even permanently damage the machine and those using it. Considering this, engineers are constantly improving upon current vibration control systems, and are now looking to birds for inspiration.

But why birds? Well, to understand this, let’s consider a bird as a simple mass-spring-damper system.

Avian vibration isolation system represented as mass-spring-damper-system
Simple approximation of avian vibration isolation system as mass-spring-damper system. Taken from the 2015 study: ‘The role of passive avian head stabilization in flapping flight.”

First, visualize vibrations as an oscillating force stemming from the bird’s body moving back-and-forth. Vibrational forces can be generated by the flapping of wings, unexpected gusts, and/or movement of legs. Now, if we continue up from the body to the neck, we can see where avian skeletal and muscular structure really begins to “show off its feathers.”

Characterized as a multi-layered structure, the avian neck contains many sections of “hollow” bones, connected by surrounding muscles. The structural units (muscles and bones) of the avian neck have properties of both springs and dampers, optimizing them for vibration isolation.

Simplified representation of multi-layered neck as spring-damper structure

For starters, we see the muscles largely act as springs. Springs have the unique ability to move a body with its vibrations. This behavior is present in the muscles connected to the bone segments, in that they are capable of instantaneously compressing, elongating and twisting in response to rapid changes in the body’s movement. This elastic response prevents not only the head, but the whole bird, from shaking when bombarded when vibrations from any form of movement.

Simplified visualization of multi-layered spring-damper structure. The transparent grey portion represents the hollow bone, which is connected by the black lines, or strong spring-like muscles. The empty space between each unit would consist of the softer, damper-like muscle. Taken from the 2021 study: “A novel dynamics stabilization and vibration isolation structure inspired by the role of avian neck.”

Alternatively, the muscles, primarily those not connected to bone, can act as dampers. Effective dampers are similarly identified by the ability to move with vibrations; however, they can dissipate some of the vibrational energy as heat, or store energy until relaxed. The interior muscles are capable of slowly deforming (changing shape) if exposed to steady vibrations, allowing for dissipation of excessive vibrational energy.

But hey, what about those bones?

The avian neck has nearly three times the number of bone sections than most mammals, on top of muscles entirely surrounding the neck. This drastically increases the bird’s flexibility, helping it maneuver through sharp positional changes, thereby further limiting the effect of vibrational forces.

Finally, what makes the avian vibration isolator truly superior is its passive activation. As engineers at Shanghai Jiao Tong University point out, manmade passive vibration isolators fall short because they require sensors and input energy to adjust for “shocks and random vibrations.” As previously explained, the multi-layered neck is well equipped to handle random oscillations, yet, more importantly, the bird’s neck muscles can passively change position to brace for incoming vibrations.

A recent study from Stanford University proved this concept by recording a whooper swan’s reaction to different strength gusts. They found that swan’s neck adjusted to protect the head, and that even when the flapping doubled, the movement of the head reduced by a quarter. Finally, it is important to note that passive activation is not limited to the sky; researchers have found that mainly terrestrial birds like chickens and pigeons have a similar neck structure and system for maintaining stability and clear vision.

Overall, continuing to study the avian vibration isolation system could prove very beneficial for many different applications. For a more in-depth look at the current work out, check-out the studies referenced throughout the article. Otherwise, enjoy watching this chicken work its body control magic!

Mercedes-Benz “Chicken” Magic Body Control Advertisement, highlighting the chicken’s amazing head stabilization ability.

How to Shine at Karaoke and Master the Art of Singing

Woman singing with microphone
Photo by Josh Rocklage on Unsplash

Are you tired of going to karaoke with your friends and not being able to master those high notes like singers Whitney Houston or Mariah Carey? While this blog post cannot promise the high quality of those amazing singers, it will demonstrate how through practice you can master the art of singing. To master singing you must first understand the biology and mechanics of your singing voice, so you can learn how to manipulate both to your benefit. This can extend to vocal production and communication studies, but the focus will be singing.

Diagram of vocal system including larynx, vocal cords, trachea
From University Physics Volume 1 on Wikimedia Commons

The vocal anatomy in the human body is composed of vocal chords, the larynx or voice box, trachea, diaphragm muscle, and airflow passages. Vocal chords, commonly referred as vocal folds, are flexible and delicate tissues that can withstand high frequency vibrations. The larynx is a tube in the human neck that holds the vocal chords. The trachea is a long tube that extends from the larynx and passes air to and from the lungs, otherwise known as the windpipe. Lastly, the diaphragm is a large muscle that separates the cavity containing the heart and lungs from the abdominal cavity. These definitions will become useful when discussing the process of singing.


Diagram of the respiratory system including the diaphragm, lunch, and trachea
From BruceBlaus on Wikimedia Commons

The organization Learn to Play Music described the biological process involved in singing in a blogpost. As humans inhale, the diaphragms contracts, the lungs expand and draw in air. During exhalation, the diaphragm relaxes, and air exits through the lungs. As air exits the “breath” travels upward through the trachea and vocal chords which begin to vibrate. This vibration leads to the production of sound which is then augmented (made louder) by areas of mouth, throat, and behind the nose. Additionally, these spaces allow the sound by vibration to last longer and affect the tone of a person’s voice. The shape of a person’s mouth, tongue, and lip movements can change the way the sound leaves the mouth by shaping the sound produced.

Music Professor Leigh Carriage at Southern Cross University analyzed how to use biomechanics to improve singing in an article. Singing involves varying pitches, loudness, voice quality (raspy, breathy, clear sounding) which requires control and coordination of muscles. These muscles must be flexible and strong which can be formed by practicing breathing control. To master singing a person needs to control the air pressure in their lungs and use their abdominal muscles to control the air flow. The most efficient way to control this pressure is through repetition or regular singing. This practice would strengthen the vocal system and improves vocal tone and power. Additionally, further expanding the abdomen when inhaling can lead to an increased contraction of the diaphragm. This would allow for more breath support when it comes to changing tone, pitch, or holding a note.

There are many biological and mechanical aspects to singing that can be analyzed to control the singing voice. See two additional readings here and here to learn more. Overall, practicing the control of your breathing during inhalation and exhalation helps master singing. By controlling the air flow, you can improve tone, pitch, and the power behind your voice at karaoke!


Check out this cool video!




The Study of Snoring is Anything but Boring

Here we take a deeper look about that noise that plagues some of our family members, our roommates…or even ourselves!

Elderly man sitting in the sun, asleep with head back and mouth open.
Photo by Stephen Oliver on Unsplash

What Causes You to Snore in the First Place?

The human upper airway contains anatomical parts that are membranous, meaning they lack support from cartilage. Some parts include the tongue, the soft palate, and the tonsillar pillars. A lack of cartilaginous support enables these parts of the airway to be susceptible to vibrations.

Anatomical diagram of the human upper airway.
Modified from Huang, Quinn, Ellis, and Williams, “Biomechanics of Snoring,” from Endeavor, 1995.

During sleep the upper airway muscles relax and cause the size of the airway space to decrease, resulting in airflow limitation and turbulence.

Whenever we inhale, the turbulent flow through the relaxed airway causes those membranous structures to vibrate and produce a sound most commonly known as snoring.

A Brief Mechanical Explanation of Snoring

Examining snoring in the view of mechanical systems, respiratory noise is created by the oscillation of the upper airway with the air passing through it. This oscillation is indicative of an issue with flow instability (turbulent flow) over a flexible structure (the relaxed airway).

An experiment was created to model the movement of the soft palate during snoring, where a piece of wood was used to simulate the hard palate and a piece of leather simulated the soft palate. The leather and wood were attached to each other inside of a rigid tube that was connected to a pump (meant to model the lung inspiration).

During inspiration, the leather flap oscillated until it reached its full amplitude. Upon reaching the maximum amplitude, the leather flap hit the wall of the tube and created a noise known as palatal “flutter”. This palatal flutter is the most common method of noise production in humans: snoring.

Is Snoring Something to Be Concerned About?

Young woman waking up in the morning, appearing tired.
Photo by Kinga Cichewicz on Unsplash

Approximately 44% of men and 28% of women are habitual snorers.

Snoring can be a symptom of obstructive sleep apnea, a condition distinguished by snoring and breathing that is labored by repetitive and obstructive gasps.

The fragmented sleep resulting from sleep apnea can lead to decreased energy and poor attention and concentration. Sleep apnea can also be related to vascular issues like hypertension and its prevalence appears to increase in people over 65 years of age.

What Are Some Remedies to Snoring?

Remedies for snoring range from noninvasive devices to invasive surgical procedures.

The surgical option to remedy snoring involves removing a portion of the vibratory tissue from the back of the upper airway. For those people wanting to avoid surgery, non-invasive solutions include the use of nasal strips to lift and open the nasal passages; experimenting with sleep positions other than sleeping on the back; or using oral appliances and nasal continuous positive airway pressure (nCPAP) to prevent the tongue and soft palate from collapsing into the upper airway. Losing weight, avoiding smoking and alcohol can also help to reduce snoring.

There are also resources for snoring in kids, as well as additional home remedies and surgical information regarding snoring.

Below is a great animated video which gives an introductory explanation to snoring.

The future of hearing might be in your bones


How many times have you walked up to someone and were unable to get their attention because they had headphones on? This is an increasingly important issue as we become more connected to our devices and less connected to the world around us. Recently, several companies, including Aftershokz and Pyle, have tried to solve this issue by creating bone conducting headphones.

How does bone conduction work?

diagrams of the inner ear displaying the differences in bone and air conduction
Modified from Furuichi, GoldenDance 2008


Although these devices may seem futuristic, bone conduction has been used for hundreds of years, especially in applications involving music. In the 18th century, Beethoven, although he had lost much of his hearing, was able to listen to his music by clenching a rod in his mouth that was attached to his piano. In most situations, we hear sounds using air conduction in our ears. Our outer ear channels vibrations that travel through the air into our ear canal where our eardrum transmits these vibrations to our cochlea. Inside the cochlea, each frequency resonates at a different location along the basilar membrane, and these mechanical waves are converted into neural signals that are transmitted to the brain. Bone conduction works by sending these vibrations through our bones directly to the cochlea and bypassing the outer ear and eardrum.

How is bone conduction used?

Szweda, BAE Systems 2015

As time and technology have progressed, bone conduction has become increasingly more common in commercial devices. Currently, the most prevalent use of bone conduction is in hearing aids for those suffering from outer or middle ear damage. Bone conduction is also used in applications where users must still be aware of their environment while listening to music or other sounds. Modern devices are able to transmit frequencies between 20 and 20,000 Hz. This range is perfect for listening to music and voices at reasonable volumes. Bone conduction can also be used in more demanding situations. BAE Systems has utilized bone conducting technology to manufacture helmets that allow soldiers on the battlefield and sailors competing in America’s Cup to communicate with each other while still being able to hear their environment. These grueling environments make perfect use of bone conducting device’s durability in hazardous conditions including water and dust.

What is the future of bone conduction?

image of LG G8 smartphone depicting the cystal sound OLED speaker screen
LG G8 Smartphone, LG Electronics 2019

Although many devices that utilize bone conduction like Google Glass and Zungle Audio sunglasses have not yet become mainstream. This technology still has a bright future. On February 24, 2019, LG unveiled its G8 smartphone which eliminated its top speaker for receiving phone calls. Instead, LG’s design creates sound by vibrating its front glass panel. The user can then press the screen against his or her face conducting the sound through his or her cheek to better hear the person on the other line. As implementations like these become more common, the technology behind bone conduction will only get better. It may seem like the future, but the next headphones or pair of sunglasses you buy might have bone conducting technology inside of it.


For more information on this story, check out The Verge and CNN.