50hz on earbuds?

[benage]

Hi, I was just reading another thread on this forum about using test tones on speakers and thought I'd like to know how low a frequency my hi-fi speakers would reproduce, so I went to this web site http://www.eminent-tech.com/music/multimediatest.html and used the 50hz tone and could hear it clearly (my speakers are 50watt Rms each, I'm not completely sure of physics behind speaker technology but it seems to be the higher watt the better low end response) Then I tried it on my lounge speakers which are only 10 watt RMS and could hear it pretty well, then tried it on my £7 earbuds and could hear it if I turned up the volume. Is this right? I know on back of ear buds it says frequency response 20-20,000 hz but I thought the amount below about 120hz on those things was negilible?

Maybe Im picking up upper harmonics or something? Any insight anyone?

P.S I tried an iPhone app doing the same thing with same result.

 

[dintymoore]

Your earbuds should reproduce the 50 Hz tone. The lowest two strings on a 4-string bass guitar are 41 Hz and 55 Hz, so if the earbuds didn't go that low popular music wouldn't sound right. You're hearing the fundamentals, the actual notes, not harmonics I'd think. Low sounds take a lot of push so you will hear them better with more wattage... but the speakers make a big difference too. It all works together.

 

[Chibi Nappa]

The lowest two strings on a 4-string bass guitar are 41 Hz and 55 Hz, so if the earbuds didn't go that low popular music wouldn't sound right.

You cannot hear the fundamental of low bass guitar notes on the majority of crappy speakers. But our brain is clever enough to cobble together overtones that are missing the fundamental, figure out what the fundamental should be, and tell us we are hearing that fundamental.

Give it a shot. Play a 41 Hz sine wave on cheap speakers (or your regular speakers with an 80 Hz high pass) and then play a low E on a bass guitar on the same speakers. One is silent, the other is a low E.

But yeah, with an ear bud driver mere centimeters from your ear drum, I imagine you could easily hear 40 hz.

 

[dintymoore]

Inside every fundamental tone, there's a 5th that is an octave and a half higher up.

When you play the 41 Hz low E on a bass guitar, you're also getting an E up an octave, at 82 Hz. Plus you get the next harmonic, which is a 5th above, and in this case would be a B note at approx 123 Hz.

Cheap gear messes with the proportions of those frequencies. You're gonna hear the octave E way more than the low E (what Chibi just said) on crappy gear. I've heard crappy car subwooofers that the bass was so messed up that the 3rd harmonic was way louder than the fundamental.

That's a very common problem and it can trick your ears until you get a sense of what's going on.

You can hear the "octave-octave -fifth" in everyday life. Even my dog messes with it.

 

[suprstar]

I did an experiment a while back just to see how low little crappy headphones can actually go. I created pure sine waves at various freq's and played em back. I was able to hear a 20Hz tone thru some walkman headphones -cheap plastic ones that came with a portable cd player from about 10 years ago - with the foam covering on the ear pieces, (not earbuds), I was pretty amazed actually. The 20Hz tone sounded kinda pulsey, not a smooth sound, but I did definitely hear it. If those shitty headphones could reproduce that, I don't beleive 40Hz should be a problem for ANY headphones or earbuds.

 

[SouthSIDE Glen]

Some earbuds will apparently deliver LF fundamentals better than you'd think because of bone conduction, It's not always just modulated air waves we hear from them. Sometimes this bone conduction is incidental, sometimes the bud manufacturer purposely designs to take advantage of this effect.

But Chibi is absolutely right also, the human ear is very adapt at "hearing" fundamentals even when they may not quite really be there based upon what they hear in the way if lower-order overtones. We're wired to do that. And sometimes the bud design takes advantage of that effect as well.

In fact, using a guitar (bass or regular) to test it is kinda unfair because much, if not most, of the energy from a guitar is actually coming from the first overtone and not the fundamental. It's our head filling in much of the fundamental for us.

G.

 

[PDP]

When you play the 41 Hz low E on a bass guitar, you're also getting an E up an octave, at 82 Hz. Plus you get the next harmonic, which is a 5th above, and in this case would be a B note at approx 123 Hz.

Cheap gear messes with the proportions of those frequencies. You're gonna hear the octave E way more than the low E (what Chibi just said) on crappy gear. I've heard crappy car subwooofers that the bass was so messed up that the 3rd harmonic was way louder than the fundamental.

That's a very common problem and it can trick your ears until you get a sense of what's going on.

You can hear the "octave-octave -fifth" in everyday life. Even my dog messes with it.

This is great info, I know exactly what your saying and it can really mess with perception. When you consider how different speakers can sound from one another, it gets very tricky, and in my experience everything else relates to the bass notes.

 

[benage]

Thanks for your help guys, it's a bit clearer now, I guess at the volume I had the earbuds to just hear the 50hz tone the rest of the upper frequencies would be close to painfull.

 

[thebigredhotdog]

Play a 41 Hz sine wave on cheap speakers (or your regular speakers with an 80 Hz high pass)

yep, the sine wave doesn't lie. a sine wave generator plugin with sweepable frequency will really tell your ears where your speakers are lacking, and what your room is doing to their sound.

 

[TeyshaBlue]

What I don't get is that if it takes approx 22 ft for a 50hz wave to propogate, how the hell are we hearing it at 2cm?

This is an unbelievably stupid question that I'm too unbelievably stupid to answer.

 

[bouldersoundguy]

What I don't get is that if it takes approx 22 ft for a 50hz wave to propogate, how the hell are we hearing it at 2cm?

This is an unbelievably stupid question that I'm too unbelievably stupid to answer.

That's a myth. You don't need to be some wavelength related distance away to hear something. Someone was probably walking around in standing waves from boundary reflections when they thought that up.

 

[TeyshaBlue]

That's a myth. You don't need to be some wavelength related distance away to hear something. Someone was probably walking around in standing waves from boundary reflections when they thought that up.

Myth? I thought it was science. I mean, a 50 hz wave is demonstrably 22 ft and change in length. I was taught that wavelength is always found by dividing the speed of light or sound, by the frequency (light or sound at a specific elevation- light is affected by atmosphere, too). For light, it's expressed as C-λ/f (Greek letter lambda/f) and for sound, a lower case 'c' is used. So you have c (1116.4ft/sec)/ 50 = 22.32 ft.

 

[SouthSIDE Glen]

What I don't get is that if it takes approx 22 ft for a 50hz wave to propogate, how the hell are we hearing it at 2cm?

While 22 feet may be the wavelength at that frequency, you dont need the full 22 feet to hear it. If you did, you'd need to have ear canals that were 22 feet wide. (Only Prince Charles and President Obama have ears that big. )

It's not the wavlength of sound that we perceive, it's the frequency (so to speak). Remember, sound "waves" are not really waves that physically go up and down in space, they instead are "waves" of alternating increasing and decreasing relative air pressure. These waves of pressure move past our ears at a (more or less) set speed we call the speed of sound (well, duh! ) The number of times the waves of pressure alternate in a second is what we connote as their frequency and that frequency of pressure change is what our ears pick up and interpret as sound of a certain pitch.

So the wavelength doesn't matter so much; a 22 ft. pressure wave will still be picked up and "heard" by most ears because we can still detect the pressure changes. It's just that they take longer to alternate between high and low; i.e. the number of waves that go buy us in a second is lower. The physical length of those waves is not relevant in that regard, it's how quickly they change.

Yes, the longer the wave, the slower the change (because the speed at which they fly by us is a virtual constant), but it's the speed of the change that we hear, not the length itself.

G.

 

[bouldersoundguy]

Myth? I thought it was science. I mean, a 50 hz wave is demonstrably 22 ft and change in length. I was taught that wavelength is always found by dividing the speed of light or sound, by the frequency (light or sound at a specific elevation- light is affected by atmosphere, too). For light, it's expressed as C-λ/f (Greek letter lambda/f) and for sound, a lower case 'c' is used. So you have c (1116.4ft/sec)/ 50 = 22.32 ft.

Microphones and ears do not need to be 22 feet wide or 22 feet away to hear 50Hz. They are sampling the pressure at essentially one point in space.

 

[TeyshaBlue]

Microphones and ears do not need to be 22 feet wide or 22 feet away to hear 50Hz. They are sampling the pressure at essentially one point in space.

Ahhh...that's the point I'm missing. Correct. It's not necessary to have a space 22 feet long to realize a wave that presents cycles at 22 ft intervals. Doh!

 

[TeyshaBlue]

While 22 feet may be the wavelength at that frequency, you dont need the full 22 feet to hear it. If you did, you'd need to have ear canals that were 22 feet wide. (Only Prince Charles and President Obama have ears that big. )

It's not the wavlength of sound that we perceive, it's the frequency (so to speak). Remember, sound "waves" are not really waves that physically go up and down in space, they instead are "waves" of alternating increasing and decreasing relative air pressure. These waves of pressure move past our ears at a (more or less) set speed we call the speed of sound (well, duh! ) The number of times the waves of pressure alternate in a second is what we connote as their frequency and that frequency of pressure change is what our ears pick up and interpret as sound of a certain pitch.

So the wavelength doesn't matter so much; a 22 ft. pressure wave will still be picked up and "heard" by most ears because we can still detect the pressure changes. It's just that they take longer to alternate between high and low; i.e. the number of waves that go buy us in a second is lower. The physical length of those waves is not relevant in that regard, it's how quickly they change.

Yes, the longer the wave, the slower the change (because the speed at which they fly by us is a virtual constant), but it's the speed of the change that we hear, not the length itself.

G.

Thanks, Glen. You and Boulder edumocated me! I knew there was a perspective I was missing here. lolz