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Sound and Hearing

The Introduction For Sound and Hearing

As we all know, sound is created by vibrations that travel through the air or another medium and can be heard when they reach a persons or animals ear. Sound is measured in decibels and sound waves can reflect off surfaces. Hard smooth surfaces are particularly good reflecting sound. Sound travels by Sound Waves and you can see these waves through an Oscilloscope.

Hearing sounds is made by the vibrations being sent through the ear, making the eardrum vibrate.

Sound waves are caused by the vibration of molecules. All the molecules bump into each other to pass the vibrations along. An example of this happening is:

Sound travels through particles by vibrations that occur from particle to particle. The particle model from the different states of matter to show this would be:

Sound travels at different speeds depending on the state of matter. For example, condensation, evaporation, etc.

Solids are very crowded and tightly packed. Unlike liquids and gasses as there are more loosely packed. Sound can travel fastest in solids as the vibrations have no gaps as they are being transferred from particle to particle.

Sound cannot travel through a vacuum because a vacuum has no particles so the sound vibrations cannot be passed on.

Foam is used in ear defenders. This is because foam is an insulator, and noises around bounce off. It is an insulator because it contains a lot of air. The ear defences expands and shapes itself into the ear canal, blocking sound to come in.

They are common to be used when travelling, as they stop your ears from ‘popping’ which most people find uncomfortable.

Pitch – High or low. Amplitude – Loudness in your ear. Wavelength - A wavelength is the distance from any point on one wave to the same point on the next wave along. All these words relate to a sound wave. Pitch relates to it by how it can be high or low, it really depends on what type of sound it is. Amplitude relates to it because some sounds can be really loud and damage your ear. Here are a few examples: blasting your music, live music and a lawn mower. Wavelength relate to a soundwave because the lower sound they are a shorter distance whereas the louder it is the bigger and a bigger distance apart from the soundwave. But why do they all relate?. They all relate because they are all types of sounds.

An oscilloscope is an instrument commonly used to display and analyse the waveform of electronic signals. A typical oscilloscope can display alternating current or pulsating direct current waveforms having a frequency as low as only 1 hertz or as high as several megahertz. High end oscilloscopes can display signals having frequencies up to several hundred gigahertzes.

Time is displayed from left to right on the horizontal scale. A voltage appears on the scale going upward and negative values going downward. The illustration shows two common waveforms as they might appear when displayed on an oscilloscope screen. The signal on the top is a sine wave; the signal on the bottom is a ramp wave.

A digital multi meter cannot be used to do this; you need another piece of electronic test equipment that is called on oscilloscope.Some instruments such as pianos and guitars can make many sounds in different pitches an oscilloscope could help find the different sound waves.

There is many different types of oscilloscopes pitches such as high and low , or soft and hard.

A pure note – this is showing the notes is the same because the height stays the same and so does to width.

Noise – this picture is showing that all the notes are different because the height is changing every time showing that the frequency is changing.

A loud, high pitched note – you can tell if it’s a high pitched note if the oscilloscope is high and the width is thin.

A soft , high pitched note – you can if it’s a soft note by looking if the oscilloscope is low and wide.

A loud , low pitched note – a loud low pitched note will still have its height but the width will change and will now be wider than the high pitched note.

A soft , low pitched note – a soft low pitch note will have the same width as number 5 but will be much shorter.

Explanation of Pictures:

1)When you speak, sound waves created by your voice carry energy toward the microphone. Remember that sound we can hear is energy carried by vibrations in the air.

2)Inside the microphone, the diaphragm moves back and forth when the sound waves hit it.

3) The coil, attached to the diaphragm, moves back and forth as well.

4) The permanent magnet produces a magnetic field that cuts through the coil. As the coil moves back and forth through the magnetic field, an electric current flows through it.

5) The electric current flows out from the microphone to an amplifier or sound recording device. you've converted your original sound into electricity! By using this current to drive sound recording equipment, you can effectively store the sound forever more.

Frequency is the number of complete sound waves every second and it is measured in Hertz (Hz). On an oscilloscope the distance between the waves shows the frequency.

Different Parts of the Ear Outer Ear- the outer ear is the part you can see. It collects sound and directs to the ear canal. Ear Canal- the ear canal is just a few centimetres long; it leads directly to the ear drum. Ear Drum- the ear drum vibrates, sending sound to the middle ear. Middle Ear- the middle ear contains three small bones called ossicles. They transmit sound to the inner ear. Inner Ear- the inner ear contains the auditory nerves and the cochlea. Cochlea- the cochlea is the sensory organ of hearing; it is shaped like a snail shell. Auditory Nerve- they are a bundle of nerves that carry information to the brain.



sound/soundandhearing.txt · Last modified: 2016/05/19 14:03 by rheadi