User:Ellis200602

The human ear
Entry 1: 21st November 2012

Starting with the three main parts of the ear, in no particular order; Your ear lobe, which is your "outer ear", the auditory canal (ear canal) the tunnel in which the sound travels through to reach the ear drum. The tympanic membrane is the part that collects the sound waves and directs it to your middle ear which is your malleus, incus, and stapes. These three bones basically conduct the vibrations sent into the ear by refractions in the air that we then interpret as sound when it reaches the brain. Entry 2: 9th January 2013

Perception of sound, the ear/brain The way the "sounds" get transferred as signals that the brain can read as sounds, the vibrations have to pass through your inner ear. Your inner ear consists of three more main parts, your cochlea, vestibule and semi-circular canals. These parts in your ear are the parts that transfer the physical vibrations that are transferred to your ear into electrical pulses, as well as the cochlea being essential for our sense of balance. These pulses are then carried to the brain via nerves attached to the ear.

The range of human hearing typically tops at 20,000 hertz (Hz) and all the way down to 20 Hz. Normally, as we get older, the frequency range that our ears can respond to, "roll off" This means that as we age, the frequencies that our ears could physically hear at a younger age, dissipate until we can't hear them any more. For example a young child before his/her teens would be able to hear 20 to 20,000 hertz. As they get older and the ear becomes fatigued, the frequency range that a person can hear would slowly decrease in range. Somebody who is 50 years old would not be able to hear a 20,000 hertz signal but a young child would. Another good example of this is when high frequency "mosquito" alarms are used outside shops or public places to put off young people from loitering, as the older generation cannot hear it.

Although our hearing range is quite large when we are young, some frequency's are "preferred" by the brain, or they appear as being louder when in fact they have the exact same sound pressure level as another frequency. This is called our hearing curve. For example my ears could hear a one thousand Htz signal then hear a 1,200 Htz signal and it appear quieter than the 1000 Htz signal, why? It is all to do with everybody's individual ear and hearing response, some ears respond better to certain frequencies and others not so much. Normally the higher we climb up the frequency spectrum, the louder we need the sound to be to hear it, same goes for the bottom end of the hearing spectrum. We need sub/bass frequencies to be louder in order to make them out.

Entry 3: 6th Febuary 2013

We have two ears which means that we hear things in "stereo" which mean two different sound sources. So our ears are essentially two microphones on either side of our head. There is a reason for them being where they are, and something that we take for granted is our brain being extremely clever in being able to interoperate where things are in an environment. So if you close your eyes, and a sound source is on your left, or somebody calls you, you know where to turn your head or find the source of sound. The reason that this happens this way is if a sound source is on your right for example, your brain will know it's coming from the right because as it reaches your right ear, it then reaches your left ear, but a fraction of a second later. In the time it takes to hear the sound, your brain has already sensed where the sound is coming from by noticing the delay or difference in time of the sound reaching the right ear to the left ear. You can also recognise different spaces and environments. If you are in a small room with lots of carpet and sound absorbing material, you can tell if you close your eyes and listen to how the sound behaves as oppose to if you were in a large hall. In a large hall there would be lots of different elements to the sound you or a speaker would create, there are lots of reflective materials like wood, hard floor, large windows, brick/plasterboard walls that would add to the timbre of the sound and they would add a reflection tail and unwanted, usually high frequencies to the sound being created. Not to mention that the space is extremely large and there would be a lot of space for the sound to fill and could result in an echo effect.

This is why it is useful in studios to have dampening and sound absorbing materials so that when your mixing down a song there is no un-wanted frequencies or nasty echoes or tails to the sound. Your'e getting a true representation of the sound source.

Entry 4: 6th March 2013

It is extremely important to look after your ears, high sound pressure levels (SPL) can result in Permanent damage to your ears.

What happens when your ear hears a loud sound?

Your ear canal, before your ear drum, are filled with thousands of tiny hairs, all different sizes to respond to every frequency in your range. Every time you hear a sound the frequencies of that sound will make the hairs vibrate. When a loud sound is produced it tears out some of these tiny hairs causes them to trigger randomly. This is what causes the ringing in your ears after a night out in a club or a live gig, and it is permanent damage, the ringing will go away, but if you continue to abuse you ears it can start staying for longer, and eventually won't go away because so many of the tiny hairs have been ripped out. This is called tinnitus, and tinnitus can be easily prevented by buying ear protection for gigs, and are essential if you are a musician and play regularly. Ear protection varies and while some cheaper options completely deaden and muffle the sound, the more up market re-usable ear plugs are designed to not impair the quality of the sound and destroy frequencies but just pad or reduce the sound by a certain amount of decibels so your hearing isn't harmed. The laws of sound pressure level exposure varies in terms of environment and exposure time. For example if you're employing somebody in a noisy environment, there are certain things you need to ensure like warning signs of excessive loud noise, issuing or making ear plugs available and limiting exposure time: Not letting the same employee spend all night or all day in a noisy environment without relevant ear protection. If you're a clubber or attending a gig, you're attending as a punter, so it would be your own responsibility to ask for or bring your own ear protection. Normally, a good venue would have ear protection available to people who ask but are not under any obligation to make you wear them when you are inside. They would also use an sound pressure level metre to accurately measure sound pressure level and make sure it's of the legal limit for the specific venue. Although there is a sound pressure level limit for venues inside, it is also your own decision to choose how long you want to expose your ears to the loud sounds. As a music technologist, working in studios the sound level in a studio can be of excess of 90dB which can cause permanent hearing damage. The highest decibel level the human ear can stand constantly for approximately one hour is 80dB, gradually over the course of the hour your hearing start to get damaged. I would recommend if you are working in a studio environment, keep monitoring level to a comfortable level, as constant exposure to sound can fatigue the human ear which can corrupt your judgement/response of frequencies, so it is essential to take regular breaks when mixing or recording a session to keep your ears fresh, and last but not least, healthy.

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