My calculus professor says that they used to use 8 cycle sound waves for crowd control. Is this true? Supposedly an 8 Hz tone rattles your insides. I guess you could call it your guts "resonant frequency" haha. Sorry, bad, bad joke. Is this true ? Perhaps that's why those infrasonic waves caused a lot of people to feel bad or whatever. Any insight on this?
How low can one hear Huh?? Say again
I read a review and the reviewer wrote "one can not hear sound below 30 htz" (??)
Of course he was referring to music.
I am not audiologist, but I think this is total B.S.
If that were so,we could all be happy with speakers that just go down to 30htz.
I've had speakers rated at 30htz, 26htz and presently own speakers rated at 20htz.
HUGE difference between the 30htz and 20htz speakers and a very noticeable difference between the 26htz and 20htz speakers.
Where is this reviewer coming from???
Of course he was referring to music.
I am not audiologist, but I think this is total B.S.
If that were so,we could all be happy with speakers that just go down to 30htz.
I've had speakers rated at 30htz, 26htz and presently own speakers rated at 20htz.
HUGE difference between the 30htz and 20htz speakers and a very noticeable difference between the 26htz and 20htz speakers.
Where is this reviewer coming from???
24 responses Add your response
golix elephants also hear (feel) through their feet from many miles away. I was watching a show the other night regarding this and at one point all the elephants in the herd would raise one front foot off the ground at the same time in response to far away sound? Falling to sleep at about this time I did not get a clear enough picture of this to fully understand. Sorry to go off topic but your post made me remember this. Dave |
Granted there are major differences in music reproduction/perception between speakers and 'phones but I fail to see the relevance when it comes to a pure tone (sine wave) as long as it reaches the ear at a high enough level to be perceived. On a different tack: We all know that bats use ultrasound to "see" and that we cannot hear this. It was recently discovered that elephants use infrasound (ie below 20Hz) to communicate we just never knew because we don't hear it! Apparently you can stand in the open savannah halfway between two elephants, which can be miles apart, and they are "chatting" to each other whilst you hear nothing! I think we can feel very low frequencies if we are in an enclosed space but we can't actually hear them and in open space where nothing resonates in sympathy we don't feel them either. |
I've just done exactly that: Fired up my modular synthesizer, plugged my headphones (5Hz-35kHz) straight into the low frequency oscilator (0.001Hz-500Hz)set it to sine wave and turned the frequency down. The result is a hum that goes lower and lower, past the well known mains hum and the pressure inside the headphones gets stronger. But then there seems to be a transition phase at about 15-20, I'd guess, where the pressure rapidly diminishes and the hum turns into separate click noises! It doesn't sound like a sinewave at all anymore. Yet when I use this signal as a modulator it turns out to be still a sinewave. So my guess is that we can hear tones below 15Hz but our brain interprets these as short burst of a tone with a much higher pitch. Any other ideas? |
Fooling around with a test disc I found (in watching the speaker cone move)a large dropout in my own hearing at about 20-25hz. I know it's there, but at that point it is out of my ears and into my belly. Upper end I'm getting worse, it goes OK to about 12k and that's it. My son can hear to 16k. I understand the sound needs to be there to be full- but the tone escapes me... |
That is going to be an individual thing. Some of us can hear lower than others. The issue seems to be less about hearing and more about exeriencing. We can still feel bass considerably lower than we can hear it. That is part and parcel of the aural experience of music. Regardless of the listeners ability to hear, the system that cuts out above 30Hz robs the listeners of the sensation associated with their music. |
The reason subs work well is because at around 60hz your ear can no longer pick-up it's location with ease. At around 25hz in my room you can hardly hear the sub even though it still measures 80 db on the spl meter...you can feel the room begin to flex. At 20hz. and 70db output as measured with the spl meter you can not hear the bass at all...you can feel the room, cement floor and everything in the room begin to shudder at this very low freq. A good test with sustained low bass freq is Archetribe (earthtones) which is " world " or newage type of music. Play it and feel your room, even if you can't hear it. Dave |
In PSYCHOLOGY OF MUSIC,Carl Seashore states that the lowest audible tone is about 16 cycles per second. It is effected by intensity(amplitude) and the form of the tone. Someone with acute hearing can hear a "pure" tone(no overtones) at about 12 cycles. With an electrical spark(almost all overtones) the low limit is as high as 100 cycles . The upper limit average for those under 40 is about 16,000 cycles. With age,it drops to about 12,000.(A cricket chirp is about 8,000.) Also,remember the difference tones. The lowest tone a string bass plays is about 4o cycles per second but it sympathetically vibrates "undertones" at 20 and 10 and 5 and 2 1/2(etc.) So,the average listener can probably hear the first difference tone but the lower ones are as much felt as heard. I can take or leave subwoofers, but the ones I've heard set up correctly(for my ear) have the volume set just high enough to be noticed-and then the volume is turned down a smigeon and the crossover is set so that cellos,trombones,and tympani come through the mid range drivers--their difference tones come through the sub(s). |
1. Even if you can't hear 20Hz, at reasonable listening levels a speaker with an F3 point of 20 Hz has much more perceived output at 30dB than one -3dB @ 30Hz. Perceptually that can correspond to more than a 10dB change at 1KHz. 2. With 10% harmonic distortion on a 20Hz tone the harmonics sound louder than the fundamental. Distortion can be a lot worse at those low frequencies. 3. The threshold of hearing goes way up at low frequencies. Below ~75dB you're not going to hear 20Hz even when your threshold of hearing hasn't increased with age or rock concerts. |
Regardless of whether any individual hears them or not, the equipment that produces these sounds is typically at its extreme edge of its performance capability to respond as low as it does. If it responds lower than we need it to, then theory would suggest that it would be more linear and within its capability to produce sound that is above its lower limits. So, in theory, it could be more linear and more in control, and better sounding in general, at frequencies above its lower limit, and thus could give better performance in whatever bass frequencies that we can hear, whatever those frequencies may be for a given individual. How about that? An argument in favor of deep bass from TWL!!! |
In order to "hear" 30Hz etc sound, you have to allow for the wave length: ~38'. Usually we FEEL the direct sound of 30Hz and we hear the reflected sound (i.e. somewhat later than it occurs). As to the reviewer, I couldn't say. 30Hz is not that low, and there's some music content there, sometimes (not much, but still). Apparently, and fortunately, he's never experienced an earthquake. That's lower than 16Hz (a large organ will produce 16Hz). Generally speaking we DO perceive low bass sounds. They are unpleasant (to me). |
I can't say for sure why that statement can be made. I've read things on hearing that says youngin's can hear down to 16 Hz and the range of normal hearing is 20 Hz to 18 kHz. I can hear (barely) the 20 Hz test tone on the Stereophile Test CD . Granted, it's not very loud through my speakers but it's still audible. It can also be felt - which is a big part of the musical expression with instruments as double basses and contrabassoons. I cannot agree more - speakers that cleanly go low 'n loud express music better. |
This article is interesting and suggests we respond to sounds well below 20 HZ, even if only emotionally. http://www.infrasonicmusic.co.uk/results.htm |
