Oh man, I hope nobody takes the some of these posts seriously. I could just see someone with black oil dripping out of their ear writting to us, Hey guys I can't hear well now, it didn't work.
Hearing is an interesting thing. Basicly mammals have the best hearing overall of all creatures. Some birds also have very good hearing, but its in a very limited range by comparison. Of the warm blooded fuzz balls, Humans actually have among the widest ranging hearing. Meaning we can hear the widest range of lows to highs. Some animals have the ability to hear above our level, ie ultrasonic such as in bats or dolphins. Some larger animals like Elephants can hear down into the 15hz range. Obviously all of these are adaptions for survival purposes. One thing we have found in studying humans is that our ability to percieve sound is radically different from that of most other animals. Our ear lobes don't move, they face forward, and our nerves and brains have adapted to this, giving us a unique ability to measure time/phase relationships in waves. Though not as accurate as say a bats, we have very precise directional abilities. However, we also have the ability to hear down quite low, giving us the ability to hear explosions, stampedes, etc. All of these wonderful adaptions for an intelligent creature like ourselves. This is something many other animals can not do. Dogs for instance are known to have hearing that extends beyond ours, is said to be more acute than ours, however they can not hear as low as us, and can not pick up something like a stampede as quickly as we can. Now having said that, Dogs do have more sensitive hearing that we do as well, so though they can't hear as low, and could not pick up a stampede as soon, they do have the counter advantage of being able to hear other frequencies of the stampede much much sooner than us, this is why dogs often pick up thunder storms before we do.
Measuring hearing is an interesting bit as well. A lot of people use their stereo's as a method to measure hearing, which is a very flawed method. Unless you know that you have a flat response at your listening position, and we are talking flat to within at least +/-3 decibles, you really can't get an accurate assessment of your hearing. The best way is to use equipment with very low distortion, very good measured performance, and headphones with a known flat response to above and below our hearing threshold. Most people don't do this, using tube headphone amps with rolled off high end response, or low end headphones with very bumpy frequency responses.
Their are biological differences between men and women in hearing too. Most women have a better high end extension than men, having the ability to hear between 15khz and say around 22khz pretty well, and normally having less loss over time. Women also are more sensitive in the upper midrange area, around where a baby's cry is. Interesting huh, scientists believe this was a biological adaption. Men on the other hand are more sensitive to low frequencies, and also have better low end extension in their hearing. It's believed that this was also an adaption to give us a leg up in car audio competitions (Or possibly survival in huinting parties). Babies have generally better hearing than adults as they have no loss, and it has been said that a baby with perfect hairing could potentially hear from 20hz to 25khz, or so. However, this is very difficult to measure, try asking a baby to listen to a 25khz test tone and say yes or no.
They actually use special brain scans for this procedure now, which brings me to my next interesting topic on hearing. Traditionally it was believed that all our hearing was sensed within the Cochlea, a fluid filled nautilus with small specialized nerve hairs. Hearing loss comes from the damage of these hairs, as many of you know. However, using brain scans, we have since found that humans are capable of hearing beyond the accepted range of 20hz to 20khz. Detailed analysis of the Cochlea shows that it physically is not responsive below around 20hz, and also isn't response above 20khz. No action is found in the nerves in frequencies much beyond 20-25khz either, yet we see the brain react to ultrasonic frequencies as high as 50khz. Even using frequencies much above that transmitted through the bones in the scull showed humans able to clearly understand speech. This has now suggested that hearing doesn't only come from the Cochlea, as previously thought, but may be a combination of the cochlea, primarily, and another nerve within the bones around our ear. We have also found that our ability to feel, our touch sense, plays a role in low frequency perception, which may give us the ability to percieve, as sound, sub sonic frequencies. However this is a very new body of research as yet to be properly documented.
Hearing is an interesting thing. Basicly mammals have the best hearing overall of all creatures. Some birds also have very good hearing, but its in a very limited range by comparison. Of the warm blooded fuzz balls, Humans actually have among the widest ranging hearing. Meaning we can hear the widest range of lows to highs. Some animals have the ability to hear above our level, ie ultrasonic such as in bats or dolphins. Some larger animals like Elephants can hear down into the 15hz range. Obviously all of these are adaptions for survival purposes. One thing we have found in studying humans is that our ability to percieve sound is radically different from that of most other animals. Our ear lobes don't move, they face forward, and our nerves and brains have adapted to this, giving us a unique ability to measure time/phase relationships in waves. Though not as accurate as say a bats, we have very precise directional abilities. However, we also have the ability to hear down quite low, giving us the ability to hear explosions, stampedes, etc. All of these wonderful adaptions for an intelligent creature like ourselves. This is something many other animals can not do. Dogs for instance are known to have hearing that extends beyond ours, is said to be more acute than ours, however they can not hear as low as us, and can not pick up something like a stampede as quickly as we can. Now having said that, Dogs do have more sensitive hearing that we do as well, so though they can't hear as low, and could not pick up a stampede as soon, they do have the counter advantage of being able to hear other frequencies of the stampede much much sooner than us, this is why dogs often pick up thunder storms before we do.
Measuring hearing is an interesting bit as well. A lot of people use their stereo's as a method to measure hearing, which is a very flawed method. Unless you know that you have a flat response at your listening position, and we are talking flat to within at least +/-3 decibles, you really can't get an accurate assessment of your hearing. The best way is to use equipment with very low distortion, very good measured performance, and headphones with a known flat response to above and below our hearing threshold. Most people don't do this, using tube headphone amps with rolled off high end response, or low end headphones with very bumpy frequency responses.
Their are biological differences between men and women in hearing too. Most women have a better high end extension than men, having the ability to hear between 15khz and say around 22khz pretty well, and normally having less loss over time. Women also are more sensitive in the upper midrange area, around where a baby's cry is. Interesting huh, scientists believe this was a biological adaption. Men on the other hand are more sensitive to low frequencies, and also have better low end extension in their hearing. It's believed that this was also an adaption to give us a leg up in car audio competitions (Or possibly survival in huinting parties). Babies have generally better hearing than adults as they have no loss, and it has been said that a baby with perfect hairing could potentially hear from 20hz to 25khz, or so. However, this is very difficult to measure, try asking a baby to listen to a 25khz test tone and say yes or no.
They actually use special brain scans for this procedure now, which brings me to my next interesting topic on hearing. Traditionally it was believed that all our hearing was sensed within the Cochlea, a fluid filled nautilus with small specialized nerve hairs. Hearing loss comes from the damage of these hairs, as many of you know. However, using brain scans, we have since found that humans are capable of hearing beyond the accepted range of 20hz to 20khz. Detailed analysis of the Cochlea shows that it physically is not responsive below around 20hz, and also isn't response above 20khz. No action is found in the nerves in frequencies much beyond 20-25khz either, yet we see the brain react to ultrasonic frequencies as high as 50khz. Even using frequencies much above that transmitted through the bones in the scull showed humans able to clearly understand speech. This has now suggested that hearing doesn't only come from the Cochlea, as previously thought, but may be a combination of the cochlea, primarily, and another nerve within the bones around our ear. We have also found that our ability to feel, our touch sense, plays a role in low frequency perception, which may give us the ability to percieve, as sound, sub sonic frequencies. However this is a very new body of research as yet to be properly documented.
pjpoes said:
I have used 2 methods:
In both cases my BEST HeadPhones,
who should have a fair response at above 10 kHz .. and at least to 15-18 kHz
This is enough to measure MY hearing.
It is NOT a low price headphone set! Or ear-plugs type.
1. A test CD with spot sinus frequencies from 20 - 20.000 hertz, in intervalls
2. My function generator feeding my headphone amplifier input.
Calibrating level for test signal
was done as I described in my post above in this topic.
lineup
Lineup Audio Hearing Lab
A funny thing I noticed with headphones (speakers might behave exactly the same) is that ones you reach the upper frequency of hearing, wobbling the generator a bit in the dead zone - which is +/-15k in my case - still reveals some notions of sound which are not noticed with a steady frequency.
Also, if you like to know more accurately what your hearing limit is, a sharp high pass filter is a nice toy to play with.
/Hugo
Also, if you like to know more accurately what your hearing limit is, a sharp high pass filter is a nice toy to play with.
/Hugo
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