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Is it my hearing or is it my stereo?

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<< large transformer in it...for some reason it seems like they make a lot of noise...anyone know why that is? Are they really making a high pitched noise? >>



Transformers runs on alternating current and it's steel lamination vibrates slightly at frequency correspoding to operating frequency. You can actually hear music from transformer if you put music through it. Large transformers with iron cores are typically powered from the line. The humming(normal) or buzzing(happens on crappy or aging transformer) is 60Hz in North America and 50Hz in Asia and Europe.
 


<< The humming(normal) or buzzing(happens on crappy or aging transformer) is 60Hz in North America and 50Hz in Asia and Europe. >>



Interesting info, thanks. Although, 60Hz is rather low, why does it seem to sound like a high pitched whine? Is that a sign of nearing failure?
 


<< For the upper limit, your hearing. Wish I had an oscilloscope.... 🙁 >>



Damn. I'm afraid so 🙁🙁🙁🙁




<< your speakers probably start losing volume past 16KHz >>





<< Do you have a SPL meter? Then you could tell if your speakers were actually outputting the sound, and gauge the rolloff at the ends. >>



I also tried using my earphones. They didn't do too well at low end as I expected, but high end wasn't any different.


Test:

I played 19KHz and 22KHz test track through my earphones. The volume was cranked up all the way. It felt completely silent by me other than pop and clicks from imperfections elsewhere.

Neither was audible to me. It's understandable if I can't hear 22KHz though. For 19KHz, I am severely disappointed.

One of my earphone was in my ear and sitting beneath the other one was a piezoelectric element. The element is connected to an oscilloscope. The earphones are actually outputting 22KHz or so says the oscilloscope.

Me hear;

when playing: nada
when stopped: nada

O'scope;
when playing: this
when stopped: nada

The "10µS" on upper right means every two horizontal squares represent 0.00001 seconds in case you don't know how to read it.

One whole cycle takes 4.4 x 10^-05 seconds and that comes to about ~22KHz just as I'm expecting... so damn it must be my hearing..

 
I can also hear the high-pitched whine of TV's, Monitors, and other stuff. I wouldn't call us 'special' or 'gifted' though. A better word would probably be 'unlucky'. Ignorance is bliss...
 
Many people can hear the TV whine. Actually, the majority of people in my class can hear it. The strange thing is that I can tell fairly accurately what color is on a television by hearing the high-pitched whine. I once scared my classmates by predicting we were going to watch a movie and predictiong what color the credits screen was from outside the classroom. 😉

Yes, I am very special
 
Just a comment on your hearing worries. On the low end at least, if you have a normal bookshelf system, then it is very doubtful that its frequency response goes down to 20 Hz. 29 Hz is a pretty popular value for the low end of the range, so that may explain why the low end was around that value. Your system most likely does go above 13.9 KHz, so it's either a problem with the system or your ears, in my opinion. Like others said though, maybe the response at those frequencies just aren't very high because of the quality of the system.
 


<< Many people can hear the TV whine. Actually, the majority of people in my class can hear it. The strange thing is that I can tell fairly accurately what color is on a television by hearing the high-pitched whine. I once scared my classmates by predicting we were going to watch a movie and predictiong what color the credits screen was from outside the classroom. 😉

Yes, I am very special >>

LOL... I got to try that once 😀
 


<< For the upper limit, your hearing. Wish I had an oscilloscope.... 🙁

The lower limit (30Hz) is more likely to have something to do with the stereo. Could you hear the tones less than 30Hz if you turned the volume all the way up?

Do you have a SPL meter? Then you could tell if your speakers were actually outputting the sound, and gauge the rolloff at the ends. >>



Could you hear the tones less than 30Hz if you turned the volume all the way up?
Better be careful! I've fried many a speaker doing that! I took out 6 of these by accident once. (well, at least 1 speaker per box). someone left a stupid test tone CD in the CD Deck, and guess who turned the PA up thinking he was gonna rock out to some Soundgarden, but instead got 15hz PURE of Square Wave? Do you know how hard it is to drive 12 of these into Odep?? NEARLY IMPOSSIBLE!
It was just too fast for the protection circuts to get there in time! 😱 :disgust:
at 30cycles, you'd probally be able to see the speaker moving, and might not hear it. You'd feel it before you'd hear it!
what you need is a tone generator! or a test tone CD like this one a quick search on google found!
 


<< Better be careful! I've fried many a speaker doing that! I took out 6 of these by accident once. (well, at least 1 speaker per box). someone left a stupid test tone CD in the CD Deck, and guess who turned the PA up thinking he was gonna rock out to some Soundgarden, but instead got 15hz PURE of Square Wave? >>



Ooh that must have made some nasty sounds 🙁

I forgot about problems with the amp clipping, I was more concerned with the speakers themselves. I've personally never experienced clipping, and it just kind of slipped my mind.

BTW he was using a test-tone CD....
 
13-14Khz is ok - depending on your age.
I ve not yet met a person that listens all up
to 20KHz.
Some people have only frequency "wholes" or degradation for a few KHz.
And of course the CD has been designed to be a bit better than the ear itself and was given some threshold. I think mp3 cuts frequencys at 15KHz ? Most people dont hear a difference.
Above 15KHz its more like feeling than listening. Some people notice a difference after relaxing and listening for a while but I ve never gotten a response like "Yes, there is a melody very high above the rest".
I can hear some car theft protections that work with active sonic sensors. But I think its just some sort of interferrence wich allows to hear a frequency between 10 and 15 KHz.
And yes, I can also hear old televisions but not my computer monitor. And no, I dont hear much above 15KHz.


 
Jerboy,
Trust me, it's your hearing. Like others have said, just because the "limit" of human hearing is 20Hz - 20kHz, that doesn't mean that everyone (or anyone) can hear the entire range. Just because you can "only" hear to 13kHz doesn't mean you have hearing damage, FM radio only broadcasts up to 15kHz, and the human ear is actually most sensitive to the mid frequencies between 500Hz - 2kHz because this is where most speech takes place. Your loss above 13kHz won't make a great deal of difference in the way music or your surroundings sound compared to the majority of people. About the worst that would be noticeable would be a slight loss of "brightness" to some music or sounds.

I worked in the Navy sonar field for a number of years and I was very surprised at how quickly a "normal" persons frequency range drops off. We were constantly working with systems which transmit frequency sweeps at audible levels through 20kHz. It never failed, I had the best hearing out of the bunch and mine signed off above 14.5kHz, we had to watch the scopes to tell when the sweep was done. That was just the low power systems, the high power systems generally transmitted at much lower frequencies which EVERYONE for miles around could hear. And believe me, when you have to listen to tone bursts from a 1.5 Mwatt sonar system for hours on end, you appreciate double hearing protection.
 
Now wait a minute. First, a crappy little mini system isn't putting out anywhere close to a linear output throughout the frequency range, electrically or sonically. It is likely way down in output at the frequency extremes. Manufacturers always say that their system puts out 20hz-20k because consumers seem to think that numbers don't lie. But the fact is THEY ARE LYING!!! What they are not telling you is it is not flat output across the frequency sweep. It is an unfortunate but common marketing practice in the audio industry. The question is how many db down is the output at those extremes. Once it drops more than 3-4db in relation to the rest of the frequency when playing music, it becomes less useable output. The fact is most cheap speakers are so far down at the extremes that it is unuseable and you guys are trying to test your hearing with that and make some sense out of it.

Second, you hooked it to an scope and measured what is coming out of the amplifier, but you are comparing it to what you hear coming out of the speakers. I guarantee those cheap speakers aren't doing a very good job of translating what is actually coming out of the amp, in addition to the fact that they are not capable of producing frequency extremes. Those speakers are NOT capable of reproducing down to 20hz. This is simple physics. To produce tones that low you need a big box for resonation and a woofer throw capable of moving a lot of air. Don't forget the sound wave at that frequency is several feet long. What you are hearing is distortion and overtones at higher frequencies. Amplifiers (and speakers as well) have a lot of trouble putting out a pure frequency tone. They will also put out other frequencies at intervals away from the original tone. Because they are at mathematical intervals and not as loud as the original frequency, you don't notice them much. When you play the low tones, you are hearing the overtones at higher frequency intervals that are high enough for those little speakers to reproduce. I have a pair of speakers with 61/2' woofers that were almost $4000 running off an equally expensive amp and they will only go down to about 50hz. But at 50hz, they are down almost 4db which means that you would perceive it as 1/4 as loud.

Third, the human ear is optimized for hearing midrange because this is where most sounds occur in nature. We are less sensitive to frequencies at the extremes. Therefore you will percieve an 85 db tone at 1k as much much louder than an 85db tone at 15k. The 15k tone would have to be 20db louder to make it sound equal to you. Ever take a hearing test at the doctor where they ask you to raise your hand when you hear the tone? Notice that the mid tones sound much louder than the high and low tones? They are playing at the same volume, it is the sensitivity of your ears that changes. Although people can and do lose hearing from damage or age, this is a perfectly normal phenomenon in normally hearing people that sound engineers understand well and adjust their mixes to accomodate.

You are using the wrong kind of test. The only way you can measure this is with an spl meter, not your ears. You need steady tones and an spl meter to measure the actual db output of the speaker. If you play 1k through your speakers and measure it with an spl meter so it is 85db (actually a mini system will probably only do 85db with the mic within a few feet of the speaker), then play 15k through your speakers and measure it and adjust the volumen so it is also 85db, it will sound much quieter to you. The key here is you are using a little mini system and there is going to be a lot of volume changing due to lack of linearity over the frequency range. Therefore using a frequency sweep on such a system like you are doing isn't going to tell you much.
 
Have any cats or dogs? Play the high-range while they're around and see if they notice. My internal PC speaker could produce sounds way out of my hearing range, but my cats were going nuts looking all over the place and almost howling.
 


<< A recent study with an African jungle people (who were picked because they don't have loud noise at all) showed
that hearing does not degrade with age - it's all damage from loud noise that accumulates over time in our
industrial world inhabitants' ears.

So Jerboy, you wouldn't be the first 17 year old with symptoms of hearing loss ... so ask yourself a few questions:
How loud do you listen to music? Do you use a portable player often? How much overkill is your car stereo? Do you
use earplugs when attending a pop/rap/rock/whatever concert?
Do you use loud power tools without ear protection? How's your workplace?

regards, Peter >>




yep... exactly what I was going to ask....

do you visit airports often? rock concerts?
 
I see most people saying it is the hearing. I think there is no basis for those statements. He has a cheap stereo. Most cheap stereos have severely limited bass response (probably 40 Hz minimum) , and unless they have a good tweeter may have limited highs as well. The human ear also has a decidedly nonlinear response, so it takes much more power at the extremes to hear something. So it depends on the power spectrum of the source as well and whether it has been adjusted to compensate for the hearing
response curve. A 20 Hz tone must have a lot of power behind it to hear it. Even then it is more like a feeling than a sound. Most speakers, especially including those thumping jobs you hear in some cars, could not hope to reproduce 20 Hz audibly. You may only hear the overtones. 20 kHz can be heard by some,
but 17-18 is the usual limit. To detect 20 Khz you should probably be in an anechoic chamber with zero ambient noise and have a controlled test performed. FYI, I know something about this, because I was tested in an anechoic chamber at the National Bureau of Standards many years ago.
 
How many people actually get tested above 16 KHz? At least around here it was my understanding was that the audiologists don't even bother testing anywhere near that high, because for most everyday situations, it's essentially irrelevant.

I have done frequency sweeps in the low end measured with a SPL meter, and I can tell you that below about 70 Hz even better quality bookshelf speakers often start to quickly lose output volume in some rooms. The difference with better brands vs. crappy brands is that the better brands admit that. Even my Paradigm Studio 60 towers (in my room) severely drop in volume below about 45 Hz. That's why I own a subwoofer. By the way 85 dB of low frequency tones kills my ears. Ouch.

Also, I do know that some crappy speakers often don't do much after around 14 KHz. Same with cheapo headphones/earphones. Even if they're top of the line speakers with -2 dB at 20 KHz, an artificial tone at 16 KHz is not going to sound loud vs. 3 KHz because the way your ear works.

As for that TV tone, I heard it much more often when I was younger than I do now. I dunno if it's because my hearing is getting worse or if it's because my TVs are getting better. Probably a bit of both, since I can still hear it easily with some really crappy TVs, and I have had my hearing measured and the sensitivity of my right ear is in the normal range but at the low end of normal. My left ear is significantly better.

Interestingly, I can also here that tone with my car, although it seems to be a much lower frequency. My car is a gas-electric hybrid, and when the electric motor is engaged I sometimes get a high-pitched whine. Most people don't initially notice it, until I point it out in a quiet area.
 
My sub can do around 23-25 cycles and I cant even hear it just see it. But I can tell from inside the house even if a light is on... which is a pretty common thing. But it does seem its a mixture of your system and your hearing. But it doesnt really matter with either. Becuase who listen to anything in those ranges?
 
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