That should be the next episode of Mythbusters, testing the hertz of the soundwave up close and far away and measuring the rate of dissipation. Afterwards than they can blow up a Sadowsky with 500lbs of Dynamite and a gallon of Gasoline.
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Bass Frequency Myth!
- Thread starter MichaelSmalley
- Start date
Well now let's actually add a little science. When talking of low frequency wavelengths, we are talking about the distance of one complete cycle of the wavelength. (eg. a complete cycle of a 41hz wave is 27 ft long) Does that mean you can't hear it up close, of course not. But this measurement is important when it comes to live sound. Take a player playing an open E string at 41hz. 27ft away the wave completes a full cycle. Fractions of a second later, the same 41hz cycle from the stage amp arrives. Depending on how far the backline is from the PA, this can make a HUGE difference in whether the bass is in your face or weak and average. If the bass amp is say 13.5 ft from the FOH stack (1/2 0f a full wave cycle) it will be perfectly out of phase with the sound from the PA. Will you hear the low end? Again of course, but it will be severely compromised. The exact same issue can occur when using a mic and a DI for bass. The DI signal arrives quicker than the mic, and again can result in out of phase, and weak bass. Often switching the phase of one of the inputs corrects the problem, but sometimes the signal isn't exactly out of phase. Using delay on one of the inputs or in the case of FOH can bring the bass into perfect phase and realize the best bass sound possible. Remember, that is some of the science of bass wavelength. Many other factors can influence what can be heard both near and far.
If you are curious about the actual cycle length of any note on the bass guitar first look up the frequency, and then enter it to find the actual length of the wave.
B0 30.8677
C1 32.7032
C#1 34.6478
D1 36.7081
D#1 38.8909
E1 41.2035
F1 43.6535
F#1 46.2493
G1 48.9994
G#1 51.9131
A1 55.0000
A#1 58.2705
B1 61.7354
C2 65.4064
C#2 69.2957
D2 73.4162
D#2 77.7818
E2 82.4069
F2 87.3071
F#2 92.4986
G2 97.9989
G#2 103.8262
A2 110.0000
A#2 116.5410
B2 123.4709
C3 130.8128
C#3 138.5914
D3 146.8324
D#3 155.5635
E3 164.8138
F3 174.6142
F#3 184.9973
G3 195.9978
G#3 207.6524
A3 220.0001
A#3 233.0819
B3 246.9417
C4 261.6256
C#4 277.1826
D4 293.6649
D#4 311.1271
E4 329.6277
F4 349.2283
F#4 369.9945
G4 391.9955
A4 440.0000
A#4 466.1640
B4 493.8835
C5 523.2512
C#5 554.3654
D5 587.3297
D#5 622.2542
E5 659.2552
F5 698.4565
F#5 739.9891
G5 783.9911
http://www.mcsquared.com/wavelength.htm
If you are curious about the actual cycle length of any note on the bass guitar first look up the frequency, and then enter it to find the actual length of the wave.
B0 30.8677
C1 32.7032
C#1 34.6478
D1 36.7081
D#1 38.8909
E1 41.2035
F1 43.6535
F#1 46.2493
G1 48.9994
G#1 51.9131
A1 55.0000
A#1 58.2705
B1 61.7354
C2 65.4064
C#2 69.2957
D2 73.4162
D#2 77.7818
E2 82.4069
F2 87.3071
F#2 92.4986
G2 97.9989
G#2 103.8262
A2 110.0000
A#2 116.5410
B2 123.4709
C3 130.8128
C#3 138.5914
D3 146.8324
D#3 155.5635
E3 164.8138
F3 174.6142
F#3 184.9973
G3 195.9978
G#3 207.6524
A3 220.0001
A#3 233.0819
B3 246.9417
C4 261.6256
C#4 277.1826
D4 293.6649
D#4 311.1271
E4 329.6277
F4 349.2283
F#4 369.9945
G4 391.9955
A4 440.0000
A#4 466.1640
B4 493.8835
C5 523.2512
C#5 554.3654
D5 587.3297
D#5 622.2542
E5 659.2552
F5 698.4565
F#5 739.9891
G5 783.9911
http://www.mcsquared.com/wavelength.htm
Lots of great response, though I didn;t read the whole thread.
In short, bass frequences "curve" and will bonce around, so hearing from a distance there's a more accurate reading of the overall blend.
HOWEVER, outdoors, where there's nothing for the sound to bounce off of, it's a purer sound and less affected by distance.
In short, bass frequences "curve" and will bonce around, so hearing from a distance there's a more accurate reading of the overall blend.
HOWEVER, outdoors, where there's nothing for the sound to bounce off of, it's a purer sound and less affected by distance.
A typical bass guitar system won't produce the fundamentals of low notes, or barely will.
Actually it can be missing completely, yet you still 'hear' it. The brain fills in the blanks for you. Even owls can do it- see the book 'this is your brain on music'....in it, the researcher Petr Janata shows that the fundamental can be completely removed, but is still 'heard.'
In short: no.
(The wisdom of attempting to summarize a thread one has not read is questionable, at best)
I was talking about this on another forum recently.
The one hang-up I have with the people who say this is a myth, and then try to prove their point by saying they can hear the frequencies up-close such as in a small room or through headphones, is that most people don't even really assign the correct frequencies to what they hear.
So many people talk about low E on a bass as if it is 40 Hz, and it's really not--more like 80 with a smattering of 160 and then a quiet foundation of 40, and so most people walk away from low E as if it were 40 Hz and assume that's what their ears are hearing. But often if you just get some harmonics you will trick yourself into hearing the fundamental too, check out Daniel Levitin's This Is Your Brain On Music. This is why I don't accept this "myth" as "debunked" just because some guy put his amp in a small room or played a tone through his headphones.
I appreciate this discussion and that's what I have to add to it.
The one hang-up I have with the people who say this is a myth, and then try to prove their point by saying they can hear the frequencies up-close such as in a small room or through headphones, is that most people don't even really assign the correct frequencies to what they hear.
So many people talk about low E on a bass as if it is 40 Hz, and it's really not--more like 80 with a smattering of 160 and then a quiet foundation of 40, and so most people walk away from low E as if it were 40 Hz and assume that's what their ears are hearing. But often if you just get some harmonics you will trick yourself into hearing the fundamental too, check out Daniel Levitin's This Is Your Brain On Music. This is why I don't accept this "myth" as "debunked" just because some guy put his amp in a small room or played a tone through his headphones.
I appreciate this discussion and that's what I have to add to it.
It's not clearly one thing.
Bass frequencies form a looser "curve' when moving than higher pitched frequencies. (Which is why a cymbal seems to go right through your brain). It's also affected by what it bounces off of. Have you ever noticed how bass notes can sound ambiguous in certain rooms, yet outdoors it's clearer?
ALL instruments sound different when you step away from them a bit. The sound needs space to "break" and expand and is different than the sound a few inches from the speaker. That's why the headphone analogy doesn't really apply. Bass always seems tighter with headphones for the very fact that it doesn't have time to warp.
That's ONE explanation.
Bass frequencies form a looser "curve' when moving than higher pitched frequencies. (Which is why a cymbal seems to go right through your brain). It's also affected by what it bounces off of. Have you ever noticed how bass notes can sound ambiguous in certain rooms, yet outdoors it's clearer?
ALL instruments sound different when you step away from them a bit. The sound needs space to "break" and expand and is different than the sound a few inches from the speaker. That's why the headphone analogy doesn't really apply. Bass always seems tighter with headphones for the very fact that it doesn't have time to warp.
That's ONE explanation.
I can't believe this is still discussed. Forget about how waves look when they are drawn on a graph. Sound is a compression wave. The wave has no physical "length", it's a measure of how long the TIME is between peaks. Compression wave means the air moves toward you and then away from you. That's it. There's no "development". In the absence of room modes or standing waves, all sound levels drop off as you move away from the speaker.
This myth happened (I believe) mostly because bass speakers are on the ground and so the bass blows by your knees. Have you ever heard anybody anywhere anytime say you had to stand far away from a pair of stereo speakers in order to hear the deep bass? If it's pointed at your head, this effect goes away. As has been noted, the back of a room can someimes be bassier because of room modes, but that is unrelated.
This myth happened (I believe) mostly because bass speakers are on the ground and so the bass blows by your knees. Have you ever heard anybody anywhere anytime say you had to stand far away from a pair of stereo speakers in order to hear the deep bass? If it's pointed at your head, this effect goes away. As has been noted, the back of a room can someimes be bassier because of room modes, but that is unrelated.
Bass waves are indeed better heard from a distance.
Doppler demonstrated this over 150 years ago.
Also, waves DO have a physical length. It isn't only a concept. Them being longer doesn't mean they take longer to form though.
Doppler demonstrated this over 150 years ago.
Also, waves DO have a physical length. It isn't only a concept. Them being longer doesn't mean they take longer to form though.
Your teacher is actually somewhat correct. Sound travels in wavelengths. The wavelength is the horizontal distance between any two successive equivalent points on the wave. That means that the wavelength is the horizontal length of one cycle of the wave. The period of a wave is the time required for one complete cycle of the wave to pass by a point. So, the period is the amount of time it takes for a wave to travel a distance of one wavelength.
The lower the frequency, the longer the wavelength so it actually takes longer for the sound to complete each cycle. You will actually hear the bass better if you back away from the source rather than being close to it. Having said that, speaker cabinet manufacturers have tried to reduce this effect by created speakers which move more rapidly and more frequently.
Here are a couple of links.
Link Removed
http://home.cc.umanitoba.ca/~krussll/138/sec4/acoust1.htm
The lower the frequency, the longer the wavelength so it actually takes longer for the sound to complete each cycle. You will actually hear the bass better if you back away from the source rather than being close to it. Having said that, speaker cabinet manufacturers have tried to reduce this effect by created speakers which move more rapidly and more frequently.
Here are a couple of links.
Link Removed
http://home.cc.umanitoba.ca/~krussll/138/sec4/acoust1.htm
These 3 sentences have nothing to do with each other.
Sentence 2 is generally correct, but it has nothing to do with Sentence 1. Treble frequencies contain less energy for the same perceived volume and are more easily absorbed. Shorter wavelengths also mean that reflections and multiple sources are more likely to cancel each other out. If you walk away from the speakers, BOTH the treble and bass will generally get softer, but the treble will get softer faster, creating the feeling that the bass got louder.
Sentence 3 is just purely wrong. A speaker cone that moves more frequently changes the pitch.
I have some background in uni level physics.
Sorry, but you are wrong. In fact, if you get further away, say go into the restroom in a club, you will generally hear the bass louder than anything else. Everything I posted came directly from the websites of speaker manufacturers. Maybe you should visit their websites. I never said I agreed with their theory. I simply posted what they are claiming.
You guys all beat me to it, but yeah - I work on radio and navigation stuff for the military, and I actually get this topic.
Like pretty much everyone has said above, bass frequencies have a longer wavelength, and are not as easily attenuated as the higher frequencies.
But you're still talking about, at least within the human range of hearing, 20Hz at the lowest. The open E string creates a note of (IIRC) roughly 41Hz. At room temperature, 70F or 0C, sound travels at 331.2 meters per second, so divide that by 41 Hz and you get roughly 8.1 meters for the actual wavelength of an open E string.
Now, with that being said, you might think that you'd have to stand 8.1 meters (or roughly 25 feet) from a bass cab to hear an open E - except we know that's not true.
Here's why -
That wave is audible along the entirety of it's wave, AND it's going from peak to peak 41 times a second. Whether you're standing 1 foot or 15 meters away, you're going to hear one solid note as this wave passes around and through you. The simple fact, as noted above, is that the bass is perceived (and is comparatively) louder because it doesn't attenuate as easily and quickly as the higher frequencies.
Also, the Doppler effect is simply the change in perceived frequency of a sound, created by changes in relation between an object creating a sound and the person hearing it.
A siren that broadcasts a 2khz tone will broadcast that 2khz tone consistently - when you hear it as pitching up, it's because the siren is coming closer to you, and when it's lower, it's because the siren is moving away from you. But the siren itself doesn't change pitch - the audio waves do, in relation to you.
Like pretty much everyone has said above, bass frequencies have a longer wavelength, and are not as easily attenuated as the higher frequencies.
But you're still talking about, at least within the human range of hearing, 20Hz at the lowest. The open E string creates a note of (IIRC) roughly 41Hz. At room temperature, 70F or 0C, sound travels at 331.2 meters per second, so divide that by 41 Hz and you get roughly 8.1 meters for the actual wavelength of an open E string.
Now, with that being said, you might think that you'd have to stand 8.1 meters (or roughly 25 feet) from a bass cab to hear an open E - except we know that's not true.
Here's why -
That wave is audible along the entirety of it's wave, AND it's going from peak to peak 41 times a second. Whether you're standing 1 foot or 15 meters away, you're going to hear one solid note as this wave passes around and through you. The simple fact, as noted above, is that the bass is perceived (and is comparatively) louder because it doesn't attenuate as easily and quickly as the higher frequencies.
Also, the Doppler effect is simply the change in perceived frequency of a sound, created by changes in relation between an object creating a sound and the person hearing it.
A siren that broadcasts a 2khz tone will broadcast that 2khz tone consistently - when you hear it as pitching up, it's because the siren is coming closer to you, and when it's lower, it's because the siren is moving away from you. But the siren itself doesn't change pitch - the audio waves do, in relation to you.
This is going to be fun.
The concept of 'waves forming' is usually associated with phased arrays - a virtual single source set up by an array lots of little sources. One could argue that a 4x10 cab is a phase array - it is. A subwoofer by itself isn't because it is a single source. I don't remember the calcs to determine how far away from the array you have to be for the wavefront to properly form but google will probably find it.
As I understand it, your ear doesn't detect high frequencies the same way it hears low frequencies. At low frequencies, your ear behaves like zero-crossing detector. It doesn't 'track' the actual sound, it detects when the signal transitions from positive to negative. This is why you can't localize bass frequencies (detect the source) - your brain gets limited information about the wave. A phenomenon which speaker engineers have exploited by having a single subwoofer in sound systems.
The concept of 'waves forming' is usually associated with phased arrays - a virtual single source set up by an array lots of little sources. One could argue that a 4x10 cab is a phase array - it is. A subwoofer by itself isn't because it is a single source. I don't remember the calcs to determine how far away from the array you have to be for the wavefront to properly form but google will probably find it.
As I understand it, your ear doesn't detect high frequencies the same way it hears low frequencies. At low frequencies, your ear behaves like zero-crossing detector. It doesn't 'track' the actual sound, it detects when the signal transitions from positive to negative. This is why you can't localize bass frequencies (detect the source) - your brain gets limited information about the wave. A phenomenon which speaker engineers have exploited by having a single subwoofer in sound systems.
After reading this thread the thing I realize is that there seems to be a huge misconception about what a soundwave actually is.....
A sound wave is a periodic variation in air pressure
The note you hear is based on how quickly that pressure changes (vs. the neutral position of your eardrum) in your inner ear. That is really what the wavelength we are all talking about here means..... Pressure changes (in and out) more quickly, the higher the note. Pressure changes more slowly, the lower the note.
The only thing that changes when you move a certain distance from a sound source is the volume of the sound you hear. Turning the volume up and standing close certainly does change how much the pressure changes, but not how quickly.
A sound wave is a periodic variation in air pressure
The note you hear is based on how quickly that pressure changes (vs. the neutral position of your eardrum) in your inner ear. That is really what the wavelength we are all talking about here means..... Pressure changes (in and out) more quickly, the higher the note. Pressure changes more slowly, the lower the note.
The only thing that changes when you move a certain distance from a sound source is the volume of the sound you hear. Turning the volume up and standing close certainly does change how much the pressure changes, but not how quickly.
Not true in the real world. The further you move from a source the more multi-path interference you get, the more frequency-dependent dispersion you get, the phase shifts, and the time delay goes up (time from send to receipt goes up, which is really the same as a phase shift as long as the path is direct). As I said before, there's a measureable distance from a phased array after which the final wavefront forms.
