A sound wave is a disturbance. When it travels through air, it bounces the air molecules around and they vibrate. They then hit other molecules and cause a chain reaction. In a different material, such as metal, sound actually travels faster. this is because the molecules are much more tightly packed (water is not dense because the molecules just roll over each other, and air is even less dense, with its molecules simply floating). This means the disturbance (sound wave) can hit more molecules and travel faster. Imagine having a big line of soccer balls, each 1 foot apart. When you kick the first, it takes a while for it to hit the second, then longer to hit the third, and so on. But if the balls were so close they almost touched, as soon as you kicked one, the last ball on the end would be moving almost instantly. This is how sound waves travel through metal and air
Parts of the Human Ear and Function
Outer Ear: The outer ear or external ear is the visible portion of the ear, which serves as a protective organ for the eardrum. It collects and guides sound waves into the middle ear. The outer ear consists of the following two parts.Ear Flap (Pinna) – The sound waves enter the ear via the ear flap or pinna.Ear Canal (Meatus) – The ear canal is about 2 cm in length. It amplifies the sound waves and channelizes them to the middle ear. Sweat glands are present in this canal, which secrete earwax.Middle Ear: The middle ear, located between the outer ear and the inner ear, perceives sound waves from the outer ear in the form of pressure waves. The middle ear is an air-filled cavity and consists of the following parts.Eardrum (Tympanic membrane) – The eardrum is a thin membrane that acts as a partition between the outer ear and the middle ear. It vibrates as soon as it receives sound waves, and transforms the sound energy into mechanical energy.Hammer (Malleus) – It is a tiny bone, located next to the eardrum.
Since it lies adjacent to the eardrum, the vibrations from the eardrum cause the hammer to vibrate.Anvil (Incus) – Anvil is another tiny bone next to hammer; it vibrates in response to the vibration of hammer.Stirrup (Stapes) – Similar to hammer and anvil, stirrup is a tiny bone in the middle ear. Eventually, it also vibrates and passes the compressional waves to the inner ear.Inner Ear (Labyrinth): The inner ear, as the name suggests, is the innermost portion of the ear. It is filled with a water-like substance and comprises both hearing and balancing organs. The inner ear comprises the following parts.Cochlea – The cochlea or the spiral tube is a rolled structure that can stretch to about 3 cm. The membrane lining of cochlea consists of numerous nerve cells. These hairlike nerve cells respond differently to various frequencies of vibrations, which ultimately lead to generation of electrical impulses.Semicircular Canals – These are fluid-filled loops, attached to the cochlea and help in maintaining the balance.Auditory Nerve – The electrical impulses, generated by the nerve cells, are then passed to the brain.
Reflection of sound waves
Reflection of a wave is the change in direction of a wave front at an interface between two different media so that the wave front returns into the medium from which it originated. The Common examples include the reflection of light, sound and water waves. When Sound wave traveling in a medium strikes the surface separating the two media A part of incident wave is reflected back into initial medium obeying ordinary laws of reflection while the rest is partly absorbed and partly refracted or transmitted into second medium. When a Longitudinal sounds wave strikes a flat surface, sound is reflected in a coherent manner provided that the dimension of the reflective surface is large compared to the wavelength of the sound.
Standing wave speed of transverse wave
This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interferance between two waves traveling in opposite directions. In the second case, for waves of equal ampletude traveling in opposing directions, there is on average no net propagation of energy .In areson ator , standing waves occur during the phenomenon known as resonance,.