Fascinating Animals

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Sounds – Test your Hearing

Pitch or frequency is measured in Hertz and Kilohertz (kHz), while the loudness or amplitude of sound is measured in Decibels.  As amplitude increases, intensity also increases.  Intensity is the amount of energy a sound has over an area.  The more energy a sound wave has, the higher its amplitude or loudness.

A sound you hear in a large area is more intense if you hear it in a smaller area.  In other words, the same sound has greater intensity or is louder in a smaller area or in the area where the sound immediately emanates from.  This is because the  energy of a particular sound distributed throughout a smaller area means more sound waves per unit of space, compared to the same sound distributed throughout a much bigger area.  In other words, in layman’s terms, the further away you are from a sound, the less likely you can hear it.

A whisper is about 10 decibels while thunder is 100 decibels.  Normal conversation is around 60 decibels, and an operating lawn mower, 100 decibels loud.  The weakest sound that can be heard is measured at 0 decibel.  There are such things as “decibel meters” which allow one to measure how loud a sound is.

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Sound TestClick on the button above to do the test

Click   HERE    to go to the Polls to record your results !

I have a Star Wars Clock in my study and at night-time when all is quiet elsewhere, it’s TICKING  is VERY noisy in my study.  The ticking of the clock seems really loud.  When there are lots of various sounds around you, it can muffle something like the ticking of a clock, but when one sound is isolated, that one sound can seem louder than it was before, but it isn’t really.  It is just that you are only now focusing on that one sound, so it just seems louder!

starwars_talking clock

Did you know that a decibel, or dB, is a logarithmic unit of measure, and that hearing loss may occur when a person is exposed to about 95 dB?  This site  HERE  explains more.

The frequency of a sound is also known as its pitch. The higher the frequency, the higher the pitch and the shorter its wavelength. There is a range of frequencies that humans and animals can hear or detect.   When humans get older, they have trouble hearing the high-pitched sounds and their detection range diminishes.  Tinnitis is a medical disorder where a person experiences a constant ringing in the ears caused by over-exposure to loud noises.  However, consider that lower amplitude noises which are constantly barraging the delicate human ears can also cause a problem.

Besides hearing low frequencies, you can often feel them.  An example of that is when you can feel the bass from a loudspeaker.  When a sound as a pressure wave reaches you, the air inside you vibrates, sometimes making your whole body seem to shake or vibrate.  I have been inside a room once with the security alarm siren going off, and I felt physically ill because the sound was not only very loud, but the pressure of the sound waves intefered with the normal vibrations of the cells in my body!

Pitch or frequencies help us distinguish between low and high sounds.  Frequency describes how fast something is vibrating.  Hertz is a measurement of frequency and one Hertz is one vibration per second.  One hertz is equal to one cycle of compression and rarefaction per second. High sounds have high frequencies and low sounds have low frequencies. Thunder has a frequency of only 50 hertz, while a whistle can have a frequency of 1,000 hertz.

Did you know that an object has a natural frequency at which it vibrates?  This is called “its resonant frequency”.  A wine glass has a natural frequency at which it vibrates. A singer can break the glass by singing a note at the same frequency.  Resonance or a matched frequency disturbed the molecules of the wine glass, causing it to shatter.

What is Sound?

Sound is a form of energy.   Energy is the ability to move something over a distance against a force.   Molecules vibrate back and forth at fairly high rates of speed, creating waves, so  energy moves from place to place by longitudinal waves.   Sound vibrations cause your eardrums to vibrate and generate what we call sound.

Sound is a mechanical pressure wave that results from the back and forth vibration of the particles of the medium (for example, air)  through which the sound wave is moving.  This page  HERE  gives an interesting explanation about this and tells you what “compression” and “rarefaction” are.

Light waves and sound waves are both forms of electromagnetic radiation with the properties of a “wave”.  To see diagrams of a light wave/sound wave, with  amplitude   labelled,  and a chart showing high energy light waves progressing to lower energy sound waves, please visit  THIS  page of my blog.

Pitches that Humans & Animals can Hear

A human being whose hearing is not damaged can hear pitches or frequencies as low as 20Hz and as high as 20,000Hz (which is 20 kHz or kilohertz).  But very few people today can hear this range of frequencies. Exposure to normal sounds in everyday modern life tends to do at least some damage to most people’s hearing at an early age. Hearing is also affected by normal aging.

hearingranges Source:   http://homepages.ius.edu/kforinas/S/Pitch.html

The above chart shows the normal range of pitches that various animals, including young human beings, can hear.  Did you know that elephants can hear low notes and dogs can hear high notes?  Any frequency that is below the human range is known as infrasound.  It is so low that it may be detected by some creatures with big ears, such as an Elephant.   Ultrasound, on the other hand, is above the range of the human ear.  Bats, whales, porpoises, and dolphins use ultrasound for navigation.

The highest pitch or frequency that a normal middle-aged adult can hear is only 12-14 kilohertz. Also, the hearing range for men worsens more quickly than the hearing range for women. This means that women will have the ability to hear notes of higher pitch than men of the same age do.

The 250-4000 Hz frequency band, where humans hear best, is described as midrange.  The pitch of the human voice is defined as the “rate of vibration of the vocal folds” .  The sound of the voice changes as the rate of vibrations varies.  As the number of vibrations per second increases, so does the pitch, meaning the voice would sound higher. Faster rates form higher voices, or higher pitches, while slower rates elicit deeper voices, or lower pitches.

The vibrations, and the speed at which they vibrate, are dependent on the length and thickness of the vocal cords, as well as the tightening and relaxation of the muscles surrounding them.  Women tend to have higher voices because they have shorter vocal cords and the rate of vibration of their vocal cords is higher.

Test your Hearing is not impaired

Try the following test to make sure you can hear within the  NORMAL  range.

As long as both ears can hear 1,000, 2,000, 3,000 and 4,000 Hertz, you are considered NOT to have a hearing impairment. 

http://www.starkey.com/hearing-loss-and-treatment/identify-hearing-loss/Online-Hearing-Test

Remember you must first “calibrate” or adjust your computer usage, either directly through the PC’s speakers or through headphones or earphones plugged into the computer. 

I tried it out using headphones and fortunately could easily hear up to 4 megahertz which demonstrates the normal everday hearing requirements.

Try the online hearing test below. 

Now, try the Test below, which measures whether you can hear up to 22,000 Hertz or 22 kHz. 

Please don’t turn up the volume on your computer so the sound is too loud for you. 

Then go in one of the Polls below.  I could not hear above 12 kilohertz.   The hearing test page says that it is fairly common for people who are over 25 years of age to not be able to hear above 15kHz, and I am nearly twice that age, so I think I can be excused.

Sound Test

 http://www.noiseaddicts.com/2009/03/can-you-hear-this-hearing-test/

Now Hear this

I was a bit surprised that I couldn’t hear higher than 12kHz because I thought that I had quite good hearing ability, but I think I was getting confused with hearing the volume / amplitude of sounds.  In other words I am quite good at picking up very soft or low volume sounds (just as long as they are within the pitch range of up to 12000 Hertz or 12kHz). So beware, if you are whispering, I just might hear you!!

 

POLLS !!

Take one of the Polls, just for fun.

Poll One

I have taken the test above (by clicking on the link under the caption “Sound Test”).   I am aged 25 or under.

Poll Two

I have taken the test above (by clicking on the link under the caption “Sound Test”).   I am over 25 years of age.

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