I was comparing the low frequency response of two speakers using a signal generator. Below 25Hz I can't hear anything. The driver's stated frequency response is 45Hz to 3KHz so the absence of audible sound makes sense. To complicate the issue the driver is moving is air and the mirror in the hall is vibrating in sympathy.
The other variable is me. Human hearing is generally quoted as being 20Hz to 20KHz but that's an approximation, and as individuals we are all built to different specifications. This begs the questions: am I personally capable of hearing 25Hz? Does the lower limit of hearing vary amongst individuals. A study of primates show interesting data, show the human hearing to be 31.2Hz to 17.6Khz.
The other variable is me. Human hearing is generally quoted as being 20Hz to 20KHz but that's an approximation, and as individuals we are all built to different specifications. This begs the questions: am I personally capable of hearing 25Hz? Does the lower limit of hearing vary amongst individuals. A study of primates show interesting data, show the human hearing to be 31.2Hz to 17.6Khz.
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The first parameter missing from this is the level of the signal.
There is a lot of research on Equal Loudness Curves. The lower frequency limit of your hearing depends on the amplitude of the signal.
A lot of the plots go down to 20Hz - If its loud enough! The minimum threshold at 20Hz is approx 75dB. Probably quite a lot more than that for us with rock & roll ears. I would be intrested to see any research that goes down to a lower frequency - Remembering that 10Hz would be another full octave.
A sealed box loudspeaker is capable of generating almost any low frequency you like, but the amplitude may be well below your audible threshold.
At lower frequencies other perception can dominate LF may be felt rather than directly heard.
Reminds me of trouser flap felt in front of a D&B audiotechnik system at Glastonbury Festival!......
There is a lot of research on Equal Loudness Curves. The lower frequency limit of your hearing depends on the amplitude of the signal.
A lot of the plots go down to 20Hz - If its loud enough! The minimum threshold at 20Hz is approx 75dB. Probably quite a lot more than that for us with rock & roll ears. I would be intrested to see any research that goes down to a lower frequency - Remembering that 10Hz would be another full octave.
A sealed box loudspeaker is capable of generating almost any low frequency you like, but the amplitude may be well below your audible threshold.
At lower frequencies other perception can dominate LF may be felt rather than directly heard.
Reminds me of trouser flap felt in front of a D&B audiotechnik system at Glastonbury Festival!......
Too many variables to list! Even the size of the room you are listening in affects the low frequencies ability to be heard. The room has to be 1165 divided by the frequency to give you the length of the room in feet to support that frequency. Small room means no low bass. That is just the beginning of things but without it your speaker can make the low frequency but you won’t hear it in that room.
The LF response of a driver in a box is dictated by it's specifications, and the box itself. Additionally as previously stated, a room will only support down to a low frequency determined by it's volume. Basically, the diagonal between the floor corner and the opposite high corner along the long dimension represents half the lowest wavelength the room will support.
For many years I have successfully designed systems using T-S parameters in whatever box was called for with the volume corrected to account for speaker, bracing, padding and anything else. This agreed with measurements using a calibrated mic, but low frequency measurements are really hard to do accurately. Using your ear is completely pointless, you are not a test instrument. You can also use some speakers in a room as the baffle (called an infinite baffle) to great effect. Slamming doors can end the woofers though. There is no best box, the speaker determines that. For enclosure-box combinations with high cut-off points you want to use either sealed, or a ported box with an electronic crossover to cut frequencies below the box resonance as the port then unloads the driver. Not a good situation as it no longer has much in the way of damping.
So no simple answer and box design does take some skill to get it right. It can be done by a DIYer using care if you educate yourself. There are speaker programs out there that can get you in the ballpark and make it easier than I did it (with a calculator, pencil and paper). But be aware the program can also give you unreasonable answers, use common sense and understand what is going on. So no substitute for understanding how it works and what is going on. Some designs can look great on paper but will never perform well.
-Chris
For many years I have successfully designed systems using T-S parameters in whatever box was called for with the volume corrected to account for speaker, bracing, padding and anything else. This agreed with measurements using a calibrated mic, but low frequency measurements are really hard to do accurately. Using your ear is completely pointless, you are not a test instrument. You can also use some speakers in a room as the baffle (called an infinite baffle) to great effect. Slamming doors can end the woofers though. There is no best box, the speaker determines that. For enclosure-box combinations with high cut-off points you want to use either sealed, or a ported box with an electronic crossover to cut frequencies below the box resonance as the port then unloads the driver. Not a good situation as it no longer has much in the way of damping.
So no simple answer and box design does take some skill to get it right. It can be done by a DIYer using care if you educate yourself. There are speaker programs out there that can get you in the ballpark and make it easier than I did it (with a calculator, pencil and paper). But be aware the program can also give you unreasonable answers, use common sense and understand what is going on. So no substitute for understanding how it works and what is going on. Some designs can look great on paper but will never perform well.
-Chris
Headphones, car cabins, and small rooms support low frequency, but small room modes affect the level that will be heard in various locations in the room.
Here is a small room that most would have no problem hearing well below 25Hz in, even before the upgrade from JBL to the Dayton drivers:
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"Other factors?"
We hear sound pressure level, it does not matter the location of the SPL, just the amplitude. If room modes reduce amplitude in one location, it increases in another.
I'm sorry, but do you understand how headphones work?
Your hearing has a log-loudness response, so what you hear isn't even close to a measured response. You can't hope to hear so many dB accurately without a great deal of training. Speaker cut-off is defined by a drop of so many dB from the mid-band response. I've been in the audio industry exceeding 45 years and used to design speaker systems. So if you have similar applied experience, I'm dying to know how you can simplify the question as much as you have.
You are correct about room modes, that is why it can be difficult to accurately measure SPL at low frequencies. That is not in dispute. What I said was factually correct. Also correct in application.
Your hearing has a log-loudness response, so what you hear isn't even close to a measured response. You can't hope to hear so many dB accurately without a great deal of training. Speaker cut-off is defined by a drop of so many dB from the mid-band response. I've been in the audio industry exceeding 45 years and used to design speaker systems. So if you have similar applied experience, I'm dying to know how you can simplify the question as much as you have.
You are correct about room modes, that is why it can be difficult to accurately measure SPL at low frequencies. That is not in dispute. What I said was factually correct. Also correct in application.
The room can certainly make a difference. With the same woofers I had rroll off below Fs (42Hz) and extension almost an octave lower in a very different room.
Chris, if small rooms don't allow for bass, how do car audio systems get those insane bass levels? Sure, much of that is mid-bass, but the room is tiny!
Chris, if small rooms don't allow for bass, how do car audio systems get those insane bass levels? Sure, much of that is mid-bass, but the room is tiny!
To answer the OP, it's a combination of things, as stated already. Fs, VAS Qts and the box you put it in or the baffle you mount it on. I don't know of nay simple answer.
As usual a comprehensive and well-reasoned answer. However, for most DIYers the opposite of the above statement is true. As 'the target listener' you are the only test instrument that matters. There have been many marketing arguments over the years; the 40KHz tweeters, the 4k phone screens. It is pointless throwing resources at things I can't see or hear. Considering local AV sources the industry is stuck somewhere between dichotomy and irony. To preserve bandwidth and storage software developers are omitting data we can't see or hear whilst the marketing department champions the extremes because customers love big numbers.
The diagonal of my room is about 12m.
The older I get, the greater my appreciation of bullet tweeters.
Do not confuse the parameters of a raw driver with one implemented in a speaker system. Even measuring a driver on an IB is only a hint to provide information on it's suitability or issues for use in a design. Then do a rough design and measure it.
I totally disagree with using ears as test for raw driver analysis. Measurement is cheap. You can get a calibrated USB mic for under $100 and a DATS for electrical measurement for not much more. Anyone without at least this level is stabbing in the dark. Their experience may lead them to success, but it is blind.
Human hearing is not 20-20. It is not even following the Fletcher Munson curve unless you were a middle-age male sampled in England one week a long time ago. Music is not either. If you want to know what you can hear, get a hearing test done.
The low frequency response depends on the enclosure. A speaker is a component of a speaker SYSTEM, which as Pano reminds you, the room is the outside of the enclosure. An integral part of the system.
No offence intended, but you need to do a lot more reading on how speakers work to be able to understand what you are asking. You also need to do more reading and listening to see what your hearing is sensitive to. In the 25 to 20 Hz range, you transition between hearing and feeling bass.
All sound is a pressure variation. All that " loading or pressure" is not understanding the definition of sound or how the ear works. Yes, the size of the room, from a couple cubic inches in a sealed headphone to outside effects what you hear and how much energy is needed to attain it.
I totally disagree with using ears as test for raw driver analysis. Measurement is cheap. You can get a calibrated USB mic for under $100 and a DATS for electrical measurement for not much more. Anyone without at least this level is stabbing in the dark. Their experience may lead them to success, but it is blind.
Human hearing is not 20-20. It is not even following the Fletcher Munson curve unless you were a middle-age male sampled in England one week a long time ago. Music is not either. If you want to know what you can hear, get a hearing test done.
The low frequency response depends on the enclosure. A speaker is a component of a speaker SYSTEM, which as Pano reminds you, the room is the outside of the enclosure. An integral part of the system.
No offence intended, but you need to do a lot more reading on how speakers work to be able to understand what you are asking. You also need to do more reading and listening to see what your hearing is sensitive to. In the 25 to 20 Hz range, you transition between hearing and feeling bass.
All sound is a pressure variation. All that " loading or pressure" is not understanding the definition of sound or how the ear works. Yes, the size of the room, from a couple cubic inches in a sealed headphone to outside effects what you hear and how much energy is needed to attain it.
No offence intended but you seem to have missed the entire point. Your screen name indicates you are a self-confessed geek. There is marked difference between a geek and a practical user. Ultimately, your goal is to produce a speaker which performs within specified / expected parameters under laboratory conditions. A practical user builds a cabinet with the sole intention of producing 'the sound they like'. The USB mic is largely irrelevant as nobody purchases music for the enjoyment of the microphone. A system producing the sound one likes may or may not compensate for one's own deficiencies. e.g. In my younger days I liked the Wharfedale XP2 series, 20 years later they sound dead to me. (The Wharfedales were bassy to begin with, now that my top-end hearing is going they sound like AM radio).
Despite obvious difference between objectivity and subjective appreciation there are often too many variables in the practical world to calculate, rendering much of the fine-tuning irrelevant. e.g. At this moment I am using a 15 litre ported sub. Any simulation data provided by WinISD or your USB microphone became useless to moment I put the cabinet in corner, under my desk, which faces the wall.
I fully appreciate the goals of those who wish to design theoretical projects but, for example, if I asked for advice on building an under-bed sub, how many would factor the effective 200mm ceiling height?
Despite obvious difference between objectivity and subjective appreciation there are often too many variables in the practical world to calculate, rendering much of the fine-tuning irrelevant. e.g. At this moment I am using a 15 litre ported sub. Any simulation data provided by WinISD or your USB microphone became useless to moment I put the cabinet in corner, under my desk, which faces the wall.
I fully appreciate the goals of those who wish to design theoretical projects but, for example, if I asked for advice on building an under-bed sub, how many would factor the effective 200mm ceiling height?
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My login is because I was the editor for the TVRCCNA technical tips many years ago. In So your insult is misplaced. I am trying to shed light on where you need more understanding, If you don't want it, fine. Not my problem. I only have 50 years of building speakers and degrees in electronics, so I too am a rookie compared to a few experts I know of. By your question, you led on to not understanding human hearing or music content.
Your question was about a raw speaker ( unless you miss-posted the question) and not about integration of sub system in a room.
FWIW, when you learn a bit more you will know why a sealed sub works far better in a room.
Yes, measurements are a starting point not the end. But without them you are tuning blind. I started in the dark ages when we had no measurements and it was very lengthy and difficult finding the trouble spots we can now do in seconds. Ear tuning is the final stage as it includes preferences.
Your question was about a raw speaker ( unless you miss-posted the question) and not about integration of sub system in a room.
FWIW, when you learn a bit more you will know why a sealed sub works far better in a room.
Yes, measurements are a starting point not the end. But without them you are tuning blind. I started in the dark ages when we had no measurements and it was very lengthy and difficult finding the trouble spots we can now do in seconds. Ear tuning is the final stage as it includes preferences.
I haven't hear this claim before. And it I'm not sure what you mean when you talk about the room not supporting the bass. Supporting as in enhancing? Supporting as in allowing sound waves to propagate at all? Can you or anyone else point me to some reading or research material on this ? I'd really appreciate that.
I understand the wavelength point, but in reality getting low frequencies in a domestic room isn't a problem. I am close to the Harman curve down to 8Hz and bass is meaningful to 5Hz. The fact that you cant hear below 20Hz doesn't change the impact and realism this adds to film and music
Hehe, nice mess. Unless a claim is supported technically, I would curb "years of experience" as a proof. We don't cite a God as a well of knowledge here in audio, do we? There are plenty dumb people doing dumb stuff for decades, getting paid for it, as long as snakeoil buyers are around.
Anyways, the wave does not exactly need to develop as long as the pressure can do the job. The only problem indeed are interferences ruining the experience.
As mentioned, a transducer, a speaker box and a room are three aspects worth of acknowledging, first separately, then as a complex system.
The transducer capability for bass is marked by motor force and displacement volume.
The box capability lays in the box size (and shape), radiators positioning, impedance management, tuning frequencies, speaker cone movement management, speaker power management, cooling. The box can do a lot of things to the outcome.
Room usually has two things. Potential for gain in bass region based on its size. Sometimes it helps, most often in rings and makes the sound boomy and slow. The second one is related - causing ugly reflections, or even adding distortion and unwanted sounds, if untreated. My drywall ceiling or stuff lying on the table could tell...
In chase for bass, you should start from the end result - what are the constrains.
What room, how big the speaker system can be, what's your budget.
If you know these, you can start choosing.
In ideal world, you need the biggest baddest speaker with most motor force and displacement volume.
These days, I would not rely on ones ear. If you get some outcome, you don't have much good tools to solve the issue in real time. The measurements have great use. You KNOW objectively, that things are righ(or not), and can correct these "spot on". Then you are allowes to play with the sound towards your liking. On the other hand, If you don't like the sound, you have way less tools in your hand to repair the issue.
I would add that in the day of modern processing, raw frequency response (or rather sensitivity) is very close to completely useless.
It's especially the case for high motor force drivers. They appear to lack bass, because they do not respond to the reference voltage well. But if you actually feed them with reference POWER, then you get significantly more bass than what you get with generic, old school approach or weak, but sensitive driver.
So, no. Ear is not the best tool for best outcome it is one valuable tool amongst all tools available. Treat it as such.
For human ear frequency sensitivity, it is individual. I got my sensitivity shifted up. In young age, I would start at 30Hz and finish at 21500Hz. At 34, I am getting down to 24Hz, but now I barely hear 19800Hz. I fear the day when I dip down to 16kHz. The music will sound like sh..... 😅
Anyways, the wave does not exactly need to develop as long as the pressure can do the job. The only problem indeed are interferences ruining the experience.
As mentioned, a transducer, a speaker box and a room are three aspects worth of acknowledging, first separately, then as a complex system.
The transducer capability for bass is marked by motor force and displacement volume.
The box capability lays in the box size (and shape), radiators positioning, impedance management, tuning frequencies, speaker cone movement management, speaker power management, cooling. The box can do a lot of things to the outcome.
Room usually has two things. Potential for gain in bass region based on its size. Sometimes it helps, most often in rings and makes the sound boomy and slow. The second one is related - causing ugly reflections, or even adding distortion and unwanted sounds, if untreated. My drywall ceiling or stuff lying on the table could tell...
In chase for bass, you should start from the end result - what are the constrains.
What room, how big the speaker system can be, what's your budget.
If you know these, you can start choosing.
In ideal world, you need the biggest baddest speaker with most motor force and displacement volume.
These days, I would not rely on ones ear. If you get some outcome, you don't have much good tools to solve the issue in real time. The measurements have great use. You KNOW objectively, that things are righ(or not), and can correct these "spot on". Then you are allowes to play with the sound towards your liking. On the other hand, If you don't like the sound, you have way less tools in your hand to repair the issue.
I would add that in the day of modern processing, raw frequency response (or rather sensitivity) is very close to completely useless.
It's especially the case for high motor force drivers. They appear to lack bass, because they do not respond to the reference voltage well. But if you actually feed them with reference POWER, then you get significantly more bass than what you get with generic, old school approach or weak, but sensitive driver.
So, no. Ear is not the best tool for best outcome it is one valuable tool amongst all tools available. Treat it as such.
For human ear frequency sensitivity, it is individual. I got my sensitivity shifted up. In young age, I would start at 30Hz and finish at 21500Hz. At 34, I am getting down to 24Hz, but now I barely hear 19800Hz. I fear the day when I dip down to 16kHz. The music will sound like sh..... 😅
Yes, the parameters of a driver are not what you get once it is in a box, and that isn't what you get in a room. I said that. However, you cannot get the best performance out of any driver unless it is in a box that suits it. Period.
Yes, you can use a driver purely as a piston (headphones for example, tiny subs), but in the case of small sub woofer boxes you need to hit the driver with excessive eq'd power. Cars are a special case, all panels are very flexible and transparent to low bass frequencies. So instead of dragging exceptions that don't relate to the OP's question (and are flawed comparisons anyway), why not study a little? You will find out that what I have said, and many others is in fact the truth.
I did a lot of work in car audio systems in the early 1980's through the early 1990's. You cannot treat the interior of a car the same as a room in a building. Then of course you can always hit a woofer-box system with tons of power and get noise. It won't be even close to flat or low distortion as in a good home system. One excellent example of this are the Bose 901 and 301. The 301 represents the truth of the physics and represents a terrible speaker. The 901 represents the application of heavy EQ on each frequency extreme (+13dB and +15dB is what I measured more than once). That is another awful speaker that some people love. Both have far too small a volume for the speakers, the 901 forces the small drivers to attempt to operate below what the box naturally will support.
Now, as far as what the person hears as being all important ... It is amazing what can pass for acceptable performance, but once you show someone a real system that performs well the suddenly understand the difference. Measured performance really does correlate to what can be heard as long as the room allows it. So while many like to minimise how well measurements describe performance, the unflattering truth is that they do. Mind you, the way the measurements are obtained can be made to lie as well. Honest measurements do matter unless you are willing to accept poor performance and refuse to face the fact that the performance isn't what you hope it might be.
Getting back to the questions. I answered it honestly in my first post. Everything matters to performance. Also, really terrible performance is often accepted too. Not my problem.
-Chris
Yes, you can use a driver purely as a piston (headphones for example, tiny subs), but in the case of small sub woofer boxes you need to hit the driver with excessive eq'd power. Cars are a special case, all panels are very flexible and transparent to low bass frequencies. So instead of dragging exceptions that don't relate to the OP's question (and are flawed comparisons anyway), why not study a little? You will find out that what I have said, and many others is in fact the truth.
I did a lot of work in car audio systems in the early 1980's through the early 1990's. You cannot treat the interior of a car the same as a room in a building. Then of course you can always hit a woofer-box system with tons of power and get noise. It won't be even close to flat or low distortion as in a good home system. One excellent example of this are the Bose 901 and 301. The 301 represents the truth of the physics and represents a terrible speaker. The 901 represents the application of heavy EQ on each frequency extreme (+13dB and +15dB is what I measured more than once). That is another awful speaker that some people love. Both have far too small a volume for the speakers, the 901 forces the small drivers to attempt to operate below what the box naturally will support.
Now, as far as what the person hears as being all important ... It is amazing what can pass for acceptable performance, but once you show someone a real system that performs well the suddenly understand the difference. Measured performance really does correlate to what can be heard as long as the room allows it. So while many like to minimise how well measurements describe performance, the unflattering truth is that they do. Mind you, the way the measurements are obtained can be made to lie as well. Honest measurements do matter unless you are willing to accept poor performance and refuse to face the fact that the performance isn't what you hope it might be.
Getting back to the questions. I answered it honestly in my first post. Everything matters to performance. Also, really terrible performance is often accepted too. Not my problem.
-Chris
Sounds more realistic.
and numerous test showing younger age groups to have high frequency around 16 to 20 Khz
Older adults can go as low as 10 to 14 Khz
depending on sound source/instrument or timber of the sound, or waveform of a sound.
Say a string instrument like Bass or Double Bass
technically the low E can be around 40 Hz
Can even Detune to low D, C or B which dips down into 30 hz or lower
The root notes are that low, but its a complicated waveform unlike a pure sinewave.
What your actually hearing is mainly 2nd and higher harmonics so 80 Hz or 60 Hz.
Guess the point is that the quoted 31.2 Hz sounds about right.
We can " hear" around that, anything below that depends on sound pressure level.
And at higher levels we tend to physically Feel it more than hear it.
Not a huge surprise.
If you did the 25 Hz test with pure sinwave no upper harmonics to hear.
Use a square wave or saw wave and you would likely " hear" 25 Hz
But realistically your hearing the upper harmonics at 50 Hz
Brain Waves can go up to 22 Hz , so its probably good we cant hear 20Hz well
or we would go insane. But a 20 Hz signal at high sound pressure.
We are really more likely to feel it than hear it. And if it was a complicated waveform
you would mostly hear the 40 Hz harmonic. But its more exciting because 20 Hz
is more a feeling and shakes and moves the room and thumps our chest
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