How low can you go? Noise floor in a silent room.

treitz3

Hello fellow Club Polk members and good morning to you all. Many of the discussions here and on other audio sites discuss high SPL levels and how good a system can sound at high volume levels. While this is a vaguely important part of audio playback, the other end of the spectrum is also an important part of audio playback as well. This thread is dedicated to exactly that.

We all have ambient noise within our house. A/C units and associated vents, refrigerators, dishwashers, computers, ballasts, electronic equipment, outdoor ambient noise, kids or spouses/girlfriends along with a plethora of other possibilities that can and will mask the minute subtleties and nuances our systems can offer. What I was wondering this morning was....how low can your room go? Even a completely silent, anechoic room will have a noise floor, unless one can remove the atmosphere of the Earth. Yes, air has noise and no one on Earth can have a zero Db listening room noise floor.

For those of you whom have never thought about this aspect of audio reproduction, give it a try. Cut off all of the known [and maybe not so known] noise sources in the room and the house. Well, at least the ones you have the power or ability to cut off. Make the room as silent as possible at the quietest time of the day or night. Then take an SPL meter and measure the room's ambient noise floor. For those who feel up to it, turn your system on with no music playing and remeasure.

How low can you go with or without your system?

While you are at it, go ahead and play a familiar track while the room is as quiet as you can possibly make it. Do you notice anything new?

Tom

Glen B

I have measured a room noise level as low as 25dB A weighted/C weighted at 5:30AM. I woke up one morning and the house was so quiet, I broke out the SPL meter to check the noise level.

treitz3

Nice! Great start to this thread. Thank you, sir.

Tom

Speedskater

So we have several questions here:

a] How low can a person with excellent hearing go in a soundproof test lab, after an acclamation time period.

b] How quite can a purpose built listening room be.

c] How quite can a typical residential room be.

d] How quite can a recording studio or concert hall be with musicians in it.

e] How low can a typical SPL meter measure. (most don't do well at low SPL levels)

treitz3

Hello, Speedskater. All of these are excellent questions. Hopefully we can address these one by one as this thread progresses. My hat is off to you, sir!

Tom