I got into a debate with a member who claimed he could hear 5hz.
Bygones.
But the issue got me thinking . . . Many people aim to build subs responding to ultra low, sub audio frequencies but with a digital signal could this exercise possibly be pointless?
Surely MP3 / MP4 encoders will discard sub 20hz input. I surmise that the majority of samplers will do the same.
I'd welcome any information to the contrary.
Bygones.
But the issue got me thinking . . . Many people aim to build subs responding to ultra low, sub audio frequencies but with a digital signal could this exercise possibly be pointless?
Surely MP3 / MP4 encoders will discard sub 20hz input. I surmise that the majority of samplers will do the same.
I'd welcome any information to the contrary.
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Although they say humans can hear as low as 20Hz when very young, as we age that number goes up. This member might actually be hearing the harmonics rather than the actual note. He wouldn't know it because when you play a 5Hz note and hear something, you auto-assume it's the note.
Vinyl cuts off at 30Hz in standard cuttings (it can be lower, but those are experimental ways of cuttting vinyl, which reduces time on the record seriously).
PCM sampling (most used digital format incls wav, aiff, flac, alac, mp3, mp4, wma, ogg, ... formats) cut of at 20Hz. About dsd i don't know but i thought the lower limit is also 20Hz.
To get lower, you will have to use formats i don't know, or use a analog source (oscillator) that can go that low. No music format i know but some special vinyl can get lower than that 20Hz.
PCM sampling (most used digital format incls wav, aiff, flac, alac, mp3, mp4, wma, ogg, ... formats) cut of at 20Hz. About dsd i don't know but i thought the lower limit is also 20Hz.
To get lower, you will have to use formats i don't know, or use a analog source (oscillator) that can go that low. No music format i know but some special vinyl can get lower than that 20Hz.
Define "practically" ; ^)
AVS forum has members that have built literally tons of cabinets with response below 10Hz, this is just one:
Ultimax 18 vs. PSA 18? 5Hz | AVS Forum
As far as MP3/MP4 encoders discarding/distorting low frequency data, the codec (coder-decoder) used (lossy/lossless) specifies the range of frequencies to allow, by establishing upper and/or lower frequency limits.
There are thousands of audio and video codecs, many popular codecs used are lossy.
The Advanced Audio Coding (AAC) codec using the MP4 container has a 0 Hz - 96 kHz audio bandwidth for standard audio channels, 0 Hz - 120 Hz for LFE channels.
Web audio codec guide - Web media technologies | MDN
Those looking for uncompressed audio formats use AIFF with Mac OSX and WAV with Windows, also no low frequency limitations with either.
What you receive depends on the codec at both ends:
Internet bandwidth
Art
AVS forum has members that have built literally tons of cabinets with response below 10Hz, this is just one:
Ultimax 18 vs. PSA 18? 5Hz | AVS Forum
As far as MP3/MP4 encoders discarding/distorting low frequency data, the codec (coder-decoder) used (lossy/lossless) specifies the range of frequencies to allow, by establishing upper and/or lower frequency limits.
There are thousands of audio and video codecs, many popular codecs used are lossy.
The Advanced Audio Coding (AAC) codec using the MP4 container has a 0 Hz - 96 kHz audio bandwidth for standard audio channels, 0 Hz - 120 Hz for LFE channels.
Web audio codec guide - Web media technologies | MDN
Those looking for uncompressed audio formats use AIFF with Mac OSX and WAV with Windows, also no low frequency limitations with either.
What you receive depends on the codec at both ends:
Internet bandwidth
Art
there was a member here claiming his rotary fan blade based subwoofer is absolutely essential and he runs it down to 1Hz!
Eminent Technology TRW-17 Rotary Subwoofer | Sound & Vision
useless and expensive I say
Eminent Technology TRW-17 Rotary Subwoofer | Sound & Vision
useless and expensive I say
This aging human has lost no low frequency hearing, but like most has lost high frequency hearing, and more than most my age, due to noise induced hearing loss.
Low-frequency hearing loss is rare, and most adult cases are due to Meniere's disease.
As I explained in a post prior to this, posts #15, 29, 35
Is 'quality' really that important down there?
Having heard and measured harmonic distortion for over 30 years, I'm well aware of what harmonics sound like, and could easily hear the 10 and 15Hz harmonics when increasing level past detection of the 5Hz sine wave tone.
That said, I have not yet heard a subwoofer system deliver 100+ dB SPL at 5Hz at typical listening distances with as low distortion as is possible with headphones.
And for those that don't hear that low with their ears to begin with, subwoofers or tactile shakers would allow them to feel those frequencies.
Art
Dude, despite what 'the Internet' tells you, you cannot hear 5hz. To make my point let me add to the things you'd be able to hear . . .
(1) The leg speed of a female sprinter.
(2) The leg speed of an Olympic walker.
(3) The low buzz of a vigorous hand-job.
(4) The leg speed of of a Derby horse.
(1) The leg speed of a female sprinter.
(2) The leg speed of an Olympic walker.
(3) The low buzz of a vigorous hand-job.
(4) The leg speed of of a Derby horse.
Neither you or opinions posted on the "internet" influence what I can or can not hear.
None of your four items could produce an SPL approaching 100 dB SPL at 5 Hz at my or your ears any more than a video of said events could, and have nothing to do with anything other than your vigor 😉
Art
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The question I have to ask is how loud does the signal have to be at 5 Hz for you to be able to hear it, compared to a signal at 100 Hz for example.
I can hear the ~8 Hz cannon blasts in the 1812 recording, but only if it's played back in my car at a somewhat elevated SPL, at which point it's being coloured by harmonics (not from the sub, but from the car's panels).
I can hear the ~8 Hz cannon blasts in the 1812 recording, but only if it's played back in my car at a somewhat elevated SPL, at which point it's being coloured by harmonics (not from the sub, but from the car's panels).
... But you can feel the "whoosh" of a large train speeding past a platform.
Infrasonics can be a lot of fun to mess around with. You can't, however, do so with headphones - our ears simply aren't suited for detecting such low frequencies.
You need real subwoofers, and a lot of them, to get below 20Hz with real authority.
Chris
Is that right?
I have seen some tracks (electronic) produce extremely low oscillations in cones, below 10Hz at least.
also think it is possible to generate a PCM file that contains just DC offset (but maybe certain DAC/ADC architecture can not produce/record pure DC, still we are only talking about sub 20Hz).
20Hz cutoff seems like good practice for 99% use cases though.
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I can definitely experience DC (steady state airflow) since I feel the air flowing from the fan on my table.
Below 20 Hz we gradually move toward an "experience" more the "hearing", and it takes a whole lot of more spl to actually get the ears to pic up the infrasonic bass.
But the more important part of infrasonics is the way they modulate the other frequencies.
This is much more important the the actual "hearing" of infrasonics.
It is quite something to play with explosives, and no bandwidth-limited sub can ever come close to the sense of energy permeating the air like the very infrasonic rich content of a 5 kg ANFO blast at 100 meters distance. The leading edge of the shock-wave has a lot of high frequency content due to the non-linear non-sinusoidal nature of the wave shape. But it is the shockwave modulating all other frequencies that enables immediate localization of where the explosion occurred.
Infrasonic content in HT does the same thing. It does add an experience and "feeling" of the extension of the space in the scene being watched, by modulating the rest of the sounds of the HT track.
Below 20 Hz we gradually move toward an "experience" more the "hearing", and it takes a whole lot of more spl to actually get the ears to pic up the infrasonic bass.
But the more important part of infrasonics is the way they modulate the other frequencies.
This is much more important the the actual "hearing" of infrasonics.
It is quite something to play with explosives, and no bandwidth-limited sub can ever come close to the sense of energy permeating the air like the very infrasonic rich content of a 5 kg ANFO blast at 100 meters distance. The leading edge of the shock-wave has a lot of high frequency content due to the non-linear non-sinusoidal nature of the wave shape. But it is the shockwave modulating all other frequencies that enables immediate localization of where the explosion occurred.
Infrasonic content in HT does the same thing. It does add an experience and "feeling" of the extension of the space in the scene being watched, by modulating the rest of the sounds of the HT track.
No. PCM goes down to DC. All lossless formats will encode DC by definition. They're just a time series of numbers.
However many audio DAC and ADC chips have an internal digital highpass filter. Some of these can be configured. And most of the analog chain is AC coupled of course, because you don't actually want any DC. The low cutoff frequency depends on the device. It is usually much lower than 20 Hz.
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This thread reminds of a light exhibition in the famous tresor club in Berlin.
Hundreds of light were moved in all kinds of directions to follow the music (short story).
1st time in such a club but I have to say those frequencies towards infrasound can easily get very distressing at those SPLs.
Literally dozens left the exhibition because they got sick or felt like their chest got hammered. I didn´t make it to the end either. I was totally stressed up afterwards and felt the need for a strong drink which isn´t like me, usually, no really.
Enjoyed an in-built oscillator from a mixing desk in a recording studio at 20Hz though played over Westlakes speaker. You could easily dry your hair with these things (back then when I had more hair)
Hundreds of light were moved in all kinds of directions to follow the music (short story).
1st time in such a club but I have to say those frequencies towards infrasound can easily get very distressing at those SPLs.
Literally dozens left the exhibition because they got sick or felt like their chest got hammered. I didn´t make it to the end either. I was totally stressed up afterwards and felt the need for a strong drink which isn´t like me, usually, no really.
Enjoyed an in-built oscillator from a mixing desk in a recording studio at 20Hz though played over Westlakes speaker. You could easily dry your hair with these things (back then when I had more hair)
But said 'whoosh' is a single movement of air. It is not a vibration.
Ah, an example . . .
Put an imperfect piece of vinyl on a record deck and crank up the bass during a period of 'silence'. The woofer will go nuts, moving violently, puffing air from the port like a snorting bull - but you won't hear any bass.
Turn it up too far and the signals below the audio range will travel through solid objects back to the stylus. At this point, the harmonics of the sub audio signal will be picked up by the stylus and cause feedback.
Well, of course running very-low-frequency signals through a ported box with no HPF will result in lots of excursion and very little LF output.
Replace your ported speakers with something big and sealed, and then you'll experience the infrasonics. By "big", I mean >110dB at 10Hz.
Turntable feedback isn't relevant to this discussion.
The train example is just to show that you can, in fact, feel air movements that your ears won't pick up. On a recording, it'll look something like the first half of a sine wave. When the rear of the train passes, you get the second half. These still count as vibrations - it's just a very low frequency.
Chris
Replace your ported speakers with something big and sealed, and then you'll experience the infrasonics. By "big", I mean >110dB at 10Hz.
Turntable feedback isn't relevant to this discussion.
The train example is just to show that you can, in fact, feel air movements that your ears won't pick up. On a recording, it'll look something like the first half of a sine wave. When the rear of the train passes, you get the second half. These still count as vibrations - it's just a very low frequency.
Chris