'Typical' room noise level for home recording spaces
 

I was wondering what those of you doing home recording have for typical room noise levels across the audio spectrum. For example, using a FFT view or simply your input recordings (showing -dB from full scale), what are your levels before any music / instruments / voice are presented? I'm particularly interested in what's typical in the under 500Hz area.

Also, if any of you have translated those -dBFS noise levels to SPL levels I'd also be interested in that.

"Room noise" can relate to several factors that may introduce unwanted audio in your recordings. Here's a paragraph from my old "home recording" page of my website that relates my experiance when moving my PC through a wall poke-through. I had before / after audio posted at one time as the difference was nothing short of astounding.

"Overdubbing vocal or instrument tracks in the same room where my DAW resides does require getting rid of the PC noise. The PC power supply and cooling fans sound like a gushing waterfall through LDCs, so I solved the problem totally by re-locating my PC to an adjacent room through a "poke through" box between the rooms. You don't even realize how nice it is to work in a room without PC noise until you've tried this. It's a worthwhile project even if you don't use your computer area for recording. Try it, you'll like it."

It is amazing the amount of ambient noise when you really need silnce..

reminds me of a recording session I did back many moons ago.

Middle of July, on the 5th floor of an old mill building where the studio was.

There was an A/C in the performance room keeping things cool until we hit record.

We learned really fast how to get it right in one or two takes. That was brutal.

My latest studio PC, an HP with SSD has no discernible noise at all. My old HP with regular hard drive was only noisy when processing CPU-intensive things which would kick the fan up to high speed.
Traffic rumble was handled by using the low-cut filter on my LDCs, but was so low as to be unnoticeable anyway.
I had a fairly noisy fridge in the next room, but never noticed its noise getting picked up - but I often used movable traps to isolate the mic


If you are experiencing noise when recording, pinpoint the source - if its your computer, then isolating the computer or the tracking mic with movable gobo-traps may be the quickest solution.

Noise floor is pretty much from mike self noise.

Noise is a can of worms, needs a book to fully address :-) What matters is signal-to-noise ratio. We frequently see people saying things like they need to turn down their mics when they record because otherwise it's noisy. But then the guitar is too soft, so they have to turn it up, and then the noise comes back up. You can also change the signal to noise ratio by how close you mic, making the guitar louder. So an absolute noise level, as measured by a decimal meter isn't very useful as an absolute number, tho it can help if you're trying to get the noise down. What matters is how the mic hears the noise relative to the guitar.

In my garage studio, fairly well isolated and treated, the noise floor varies - depending on external traffic, what's running inside the house, etc, but if I record late at night, I can get a noise floor of -60 to -70 db. A lot of the noise is low-frequency hum, probably from the refrigerator, etc, traffic rumble and so on. It helps to use a high pass filter below 40-50Hz. Then I'm probably mostly left with mic and preamp self-noise.

A recent collaborative project provides an interesting look of different people's noise floors in more casual home setups. We had 4 people recording in 3 spaces. I recorded in my video room/spare bedroom, which is not treated, not isolated, and not nearly as quiet as the studio space. The others recorded in their living rooms. Here's what I see on those audio files. All measurements are RMS, done in RX, tho I'd get about the same numbers if I measured both as peak values.

Mine: "silence" is -72db, guitar is recorded at -20db, so -52db noise floor relative to the guitar

player 2, living room: "silence" is -53db, guitar recorded at -15db, -38db noise floor

Players 3,4: -"silence" is -55db, guitar recorded at -23db, so -32db noise floor

That's pretty noisy, but it seems typical of home recording in rooms where neither acoustics or isolation have been dealt with, and the resulting video, even adding all 4 recordings together doesn't seem particularly noisy to me.

This is the polar opposite of a solo guitar in a room, but you might find it interesting. The guy's in his LA backyard with a single USB mic at rush hour, about a hundred yards from San Vicente Blvd.

This is one advantage of building your own PC--you can select components that will minimize noise. Those include SSDs, a low-noise power supply, a high-performance, low-noise CPU cooler, large, low-noise case fans, and a case with good ventilation. Even without SSDs, my recording PC is effectively nearly silent, and cannot be picked up by my LDC mics six feet away.

Did that a few years ago. Thread here:
https://www.acousticguitarforum.com/...d.php?t=317927

Thanks for the information.

The laptop I used seems pretty quiet, compared to most desktops. I did move it to increase the distance to the mics by about 5x, which should decrease the it's noise level at the mics by about 14dB, but there was no change in my most problematic range under 200Hz.

Thanks for the thought.
Well it's not the HVAC, at least not this time. The weather we're having is perfect; no heat on, no AC on, no fan on.

Thanks for the ideas.

Very well could be the fridge in the next room, but when I opened the door to that room there was no change in the noise level. Still could be the source though.

The highest noise level in my room is a fairly narrow band at 50-60Hz, also nearly as high at 30Hz (when the HPF is off), also some noise but lower in the range of 120Hz and 180Hz (which the HPF doesn't help as it gets set in the range of 50-75Hz.

What!!!! I want your room (because I know how quiet your mics and preamp are).

Hi Doug,
Thanks for all the detail.
I agree that it's all based on signal to noise ratio. Also, I especially appreciate all the example recording levels you provided; it's nice to have a reference.

The worst noise for me is a pretty narrow band around 50Hz to 60Hz, not quite as bad around 30Hz, and lower but present at 120Hz and 180Hz. So, it sure seems related to equipment/appliances running off of line power. The 60Hz level is at -60dB down from full scale. When I have my HFP set to 50Hz the level at 50-60Hz drops to around -63dB. I can set my HPF a bit higher (mayber 75Hz) and get improvement for the 30Hz and 60Hz noise, but it obviously doesn't help at higher frequencies. (The test was done fairly early in the morning; no road noise. House closed up. No HVAC on. No fans on. Fridge could be the source.)

Using the mics and gain and HPF that results in -63dB noise floor at 60Hz, my recorded signal are generally in the range of -20dB with peaks around -10dB. So, the S/N isn't great at the low end of the spectrum, but maybe not atypical of home rooms. The problem seems to be that there is quite a level of mud below 200Hz, of particular concern as the s/n is not very good if I'm playing low notes not too loudly.

I'm also not sure how much better I should expect the low frequency noise to get. I know my mic sensitivity, preamp gain, and ADC full scale calibration level, so I was able to calculate the SPL level of the room noise in the 50-60Hz band; it comes out to 43dB SPL. Maybe I can get it somewhat lower, but for a home room I don't think it's too far out of the normal range.

As I noted, "room noise" can originate from a variety of sources. The PC is but one example.

Your job is to isolate the cause, and it can be from something that you weren't even considering. Since you're using a laptop you can go back to your main breaker box and shut off circuits until you find the culprit, assuming it's not environmental, such as nearby traffic.

Even better is to shut EVERYTHING off and see if you still have a problem. I once had a low rumble that was caused from the main air mover on my AC in the basement. The low rumble traveled quite effectively through the insulated duct work and I could only hear it during playback of a recording made with a LDC.