Low level audio
- Thread starter Lexie1960
- Start date
rob aylestone
Moderator
Well, it would be difficult in normal spaces to get a reading that low. The computer in my computer cupboard means that according to my phone dB meter, my silence is just above 30dB. What on earth are you trying to capture? Ants farting?
TalismanRich
Well-known member
I would say you could get sound that low, if it is well below your ambient level. Typical homes will often be in the 30-40dB range. Maybe if you were inside a cave deep in the earth, you would get levels down there. Or built a special chamber with lots of soundproofing and isolation.
A mic with a low self noise would help, as you could easily boost the signal in a DAW.
A mic with a low self noise would help, as you could easily boost the signal in a DAW.
I understand this. Your additional response of 'Ants farting', what that really necessary....
First time ever that I joined a site, and in the same day I leave the site. Nothing worth listening to here...
Goodbye.
rob aylestone
Moderator
It is called humour - you know, things that make people smile. I rather assumed that you come back with ha ha, no what I'm doing is xxxxxxxxx - but when you post to strangers a bit of supporting information comes in handy - as in as 20dB (an any measuring variant) is virtually silence - what on earth are you doing? Incidentally, you can get scientific transducers that can measure changes in pressure in very small magnitudes, but they are not really microphones from the research I did - conventional audio transducers seem to have a low limit of around 30dB - so you're into expensive scientific kit, not microphones.
It's always a good policy to read a forum, to get a feel for how questions are structured and the response types. We have some very useful people, but it's a little sad to not be able to identify humour of the lightest kind - as in you want to record something so quiet it's probably the level of an ant fart? I'm sorry for your offence taken, it certainly wasn't meant.
I'd also suggest the comments to the question on many forums would be also be quite sharp - because 20dB without the method of measurement is pretty vague - at that level, the scale of measurement is important, plus the frequency? I didn't go that far figuring you'd smile and explain, not take the hump like this.
It's always a good policy to read a forum, to get a feel for how questions are structured and the response types. We have some very useful people, but it's a little sad to not be able to identify humour of the lightest kind - as in you want to record something so quiet it's probably the level of an ant fart? I'm sorry for your offence taken, it certainly wasn't meant.
I'd also suggest the comments to the question on many forums would be also be quite sharp - because 20dB without the method of measurement is pretty vague - at that level, the scale of measurement is important, plus the frequency? I didn't go that far figuring you'd smile and explain, not take the hump like this.
I do hope our sensitive friend returns* I would also say that 20dB (assume that means "SPL"? A weighted?) is 'silence' but if i can put in my 2 penn'o'th? I have a basic SPL meter and it never reads below about 25dBC even when I hear nothing with both aids cranked. Similarly, the SPL app on my phone does not register levels below 25-30dBC. (if SF is still looking in. The C weighting is used for calibrating loudspeakers and is nearly 'flat'. A weighting is really just for industrial/road noise and legal matters) . I suspect 20dB ish is the electronic noise floor for any but the most expensive SPL meters? To do better I think you would need 'averaging techniques' as found on AP system audio test rigs?
*Lexie, you will search far and be very unlikely to find an audio forum as civilized as HR. soundonsound.com is another one, lovely folk there. Had you asked such a question on many forums ten years ago many of the replies would have been of the form..."What TF are you asking such a ***** question for!!! 20dB is (**&^%ing silence!!. Please give the guys and gals here another do?
Dave.
*Lexie, you will search far and be very unlikely to find an audio forum as civilized as HR. soundonsound.com is another one, lovely folk there. Had you asked such a question on many forums ten years ago many of the replies would have been of the form..."What TF are you asking such a ***** question for!!! 20dB is (**&^%ing silence!!. Please give the guys and gals here another do?
Dave.
sweetbeats
Reel deep thoughts...
I agree 100%. I thought it was a humorous way to beg the question “What is it you’re doing anyway?” I was looking forward to an informative response…but no such luck. Hey do ants actually fart?
sweetbeats
Reel deep thoughts...
I think the response on 95+% of the platforms would have been something like “yeah in your butt” or something like that.
rob aylestone
Moderator
I'm sure that years back I read about a transducer designed for really low level sound. It was a piece of gold foil that was only suspended from the top edge and another behind it that was taut in a frame and used capacitance change like a normal condenser, but I can't find it anywhere - I've searched but this would have been probably twenty years ago so way out of date on the modern internet.
It was inside a housing that looked like a small carriage clock, design wise, but with fine mesh on four sides.
It was inside a housing that looked like a small carriage clock, design wise, but with fine mesh on four sides.
I remember seing a design based on a Carbon contact mic using a pencil lead in sort sort of balance. The problem of course is not so much the transducer but keeping ambient noise out but not knowing the application we are banjaxed.
Dave.
you must mean -20dbfs.
Since A/D converters are not constant in regards to its signal to noise, bringing in a signal that low will have a lower signal to noise ratio. A lot of people settled on -10 dbfs as a recording level for these circuits that were really not well design to record audio.
TalismanRich
Well-known member
I think you misunderstood the original idea. It's not wanting to know if you can set a recording at +20dB. Lexie wants to know if you can record a sound at a 20dB level. Zero dB is supposed to be the lowest limit of hearing (20uP). Very calm breathing is 10dB or so. Quiet residential rooms are typically at 30dB or more. Deep, dry caves are generally around 0dB. I've been deep inside Mammoth cave with about 8 other people many years ago on the wild cave tour. It's a tour that goes through small passages, no lights except for helmet lamps, with lots of crawling and squeezing through small area. At one point, we all stopped, sat down in a passage, turned off our helmet lamps and sat as quietly as we could. It was almost unsettling how dark and quiet it was in a small passage hundreds of feet underground. After a few minutes, you could hear the person breathing a few feet away. You could hear the blood rushing through your head. You couldn't see your hand in front of your face.
For years the quietest anachoic chamber was -9dB at a lab in Minneapolis MN. Microsoft built one some 10 years back that measures -20.6dB. It is officially the quietest place on earth. No sound and no reflections.
RE the original post, breathing is approximately 10dB, and a whisper is around 20dB. With enough gain, you can certainly record someone's breathing and a whisper, assuming the background is quiet enough. If your background level is 40dB, you're not going to be able to pick out the breathing easily.
grimtraveller
If only for a moment.....
Last week, I was recording a bongo part on this song that is pretty loud and electric and some days later, when I was listening to the bongos in isolation, I was surprised to hear my breathing in parts. The mic {an AKG C1000 through an ART II pre-amp} was about 18-24 inches away from the bongos and pointing down. Recorded in my son's bedroom, there would have been the usual distant ambient sounds that might get picked up if there were no bongos playing {the bus, cars going by, arguments, kids playing, loud teenagers being loud teenagers, fighting cats, barking dogs, the toilet flushing, the TV downstairs etc}; the noise floor here is generally wonderful ~ you can hear things in isolation, but very quietly, not enough to appear on a flute track in a way that interferes.