Sound is something we can hear when it travels through the air or another material. It happens when something makes the air around it move, kind of like a ripple in a pond. But, we can also make sounds that are too high or too low for our ears to hear. Dogs can hear some sounds that we can’t, like the sound of a dog whistle. And, there are machines that use sound to “see” things, like a submarine that uses sonar to find other objects in the water. Some daily life examples of sound waves are listed below:
- When you listen to music through headphones, sound waves are traveling from the device to your ears.
- The noise from a car engine is produced by sound waves created by the engine’s motion.
- The sound of a dog barking or a baby crying is both caused by sound waves in the air.
- Thunder is created by the sound waves produced by lightning.
- The ringing of a telephone is the result of sound waves being produced by the phone’s speaker.
The speed of sound in a given medium is calculated using the formula:
v = fλ
where:
- v is the speed of sound;
- f is the frequency;
- λ is the wavelength.
Table of Contents
Physics Behind Sound Waves
- Sound waves are created by vibrations that travel through a medium.
- A disturbance in the medium causes a series of compressions and rarefactions to move through it in the form of a wave.
- Sound waves have properties such as frequency, wavelength, and amplitude.
- Frequency is measured in Hertz (Hz) and represents the number of waves that pass a given point in a second.
- Wavelength is measured in meters (m) and is the distance between two adjacent points in a wave that is in phase with each other.
- Amplitude is measured in decibels (dB) and is the maximum displacement of a wave from its equilibrium position.
- Sound waves can be reflected, refracted, diffracted, and absorbed as they travel through different mediums.
- Acoustics is the study of sound waves and their behaviour, with applications in engineering, music, medicine, and other fields.
Formulas Related to Sound Waves
| # | Formula | Units |
| 1 | Wave velocity (v) = frequency (f) x wavelength (λ) | m/s = Hz x m |
| 2 | Wavelength (λ) = wave velocity (v) / frequency (f) | m = m/s / Hz |
| 3 | Frequency (f) = wave velocity (v) / wavelength (λ) | Hz = m/s / m |
| 4 | Amplitude (A) = maximum displacement from equilibrium position | m or Pa (Pascals) |
| 5 | Intensity (I) = power (P) / area (A) | W/m^2 = W / (m^2) |
| 6 | Sound level (β) = 10 log(I / I0) | dB, where I0 is the threshold of hearing (W/m^2) |
| 7 | Doppler effect: f’ = f(v + v_r) / (v – v_s) | Hz, where v and v_r and v_s are in m/s |
Properties of Sound Waves
| # | Property | Description | Examples |
| 1 | Amplitude | A longer wavelength corresponds to a lower-frequency sound, such as a bass guitar. | The sound of a car horn is louder than a whisper. |
| 2 | Frequency | Distance between two consecutive points in a sound wave that is in phase. | A high-pitched sound has a higher frequency than a low-pitched sound. |
| 3 | Wavelength | The speed at which the sound wave travels through a medium depends on the properties of the medium. | A number of complete oscillations of the wave per unit of time determine the pitch of the sound. |
| 4 | Velocity | The amount of energy per unit area per unit time carried by the sound wave determines its loudness. | Sound travels faster through water than air. |
| 5 | Intensity | The bouncing of a sound wave off a surface can cause echoes and reverberation. | A jet engine produces a much more intense sound than a ticking clock. |
| 6 | Phase | The bending of a sound wave as it passes from one medium to another can affect its velocity and direction. | Two sound waves that are out of phase will cancel each other out. |
| 7 | Reflection | The relative position of a point on a sound wave compared to a reference point affects the interference and superposition. | Sound reflecting off a canyon wall creates an echo. |
| 8 | Refraction | The bending of a sound wave as it passes from one medium to another, can affect its velocity and direction. | A sound wave passing through a glass window is refracted. |
| 9 | Interference | Interaction of two or more sound waves that overlap, which can result in constructive or destructive interference. | Two identical sound waves that are in phase will interfere constructively. |
| 10 | Doppler effect | Change in frequency of a sound wave due to the relative motion of the source and observer, which can result in a change in pitch. | The sound of an approaching ambulance siren sounds higher in pitch than when it is stationary. |
How we hear sound: What happens when sound waves reach the outer ear?
- Sound waves are collected by the outer ear (pinna and ear canal).
- The eardrum vibrates in response to the sound waves.
- Vibrations are transmitted to the ossicles in the middle ear (malleus, incus, stapes).
- Ossicles amplify and transmit vibrations to the oval window in the inner ear.
- Vibrations cause fluid in the inner ear to move and stimulate hair cells in the cochlea.
- Hair cells convert mechanical vibrations to electrical signals sent to the brain via the auditory nerve.
- The brain interprets electrical signals as sound, allowing us to hear and perceive the world around us.
More Links
Damped Oscillation| Formula and Daily Life Examples
Crest of a Wave| Wave Properties| Easy Points
Transverse waves| Definition and Daily Life Examples
Compression Waves
Stationary Waves| Definition, Properties
Longitudinal Waves| Daily Life Examples
PhD Student at University College Dublin and Author at What's Insight
PhD Student who loves to write about science, technology and more. Studying at the University College in Dublin. Hope you enjoy my content.
Please send any feedback to [email protected]
Please send any feedback to [email protected]
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