Automated Noise Floor Correction Facility (for use in club environment)

[Ridi_Ree]

Hello fellow electricians,
Im a student studying in my third year in the south of england, for my third year project im designing a filtering/weighting network capable of taking a reference feed from the surrounding environment (dBspl) in a club atmosphere and comparing it with an inverse feed from the sound desk or what ever device that the music is playing out of.

If you could aid me in anyway as for the design elements (esp filter knowledge), i would appreciate this very much.

Little Background: Using a Op Amp Comparator with feeds from the reference and the background level (only using one mic for the prototype) with an averaging RMS detector, overload limiter,weighting network

Thnk u

Ridi Ree

 

[audioguru]

Years ago I used a similar system made by Altec.
It sensed the noise at an airport and adjusted the level of the paging.
It turned off the sensing during paging.

 

[Menticol]

Maybe using a computer, the microphone, and SONY's sound forge (specificaly the included noise floor tool), you can make some kind of interface between all these components (via software)

 

[Ridi_Ree]

I was going to refer to that in my recomendations at the end of the document, that it can be used in other circumstances, such as train stations/airports and in motor vehicles

 

[audioguru]

But aren't you supposed to design a system? The old system that you are simply copying has been in use for years.

 

[ericgibbs]

I was going to refer to that in my recomendations at the end of the document, that it can be used in other circumstances, such as train stations/airports and in motor vehicles

hi,
A system has been in use on many UK railway stations for a number of years, IIRC Plessey? used the paging speakers as microphones to sample the 'background noise', before making an announcement over the speakers.

The systems I heard were quite audible over a wide range of background noise.

 

[Ridi_Ree]

But aren't you supposed to design a system? The old system that you are simply copying has been in use for years.

Im designing it in a completely different way for a completely different reason? Forgive me if im wrong, but im just borrowing a few concepts which is what most engineers do in the industry.

The terminal background noise level system sounds like it could really help me out, im not going to be making this design digital, althought at my degree show i may have to use a computer to aid me in describing the theorem behind my protype.

THnx everybody, any more help would be greatly apperciated

 

[audioguru]

Oh. You are making a simple circuit to replace the Disc Jockey who turns up the volume as the time gets later.

I don't think you will find a noisy train or jet airplane in a club so I don't know what your "filtering/weighing network" will be sensing. In the UK do people scream in a club? Dogs barking?

My car radio automatically turns up the volume when a certain speed is exceeded. It assumes that the background noise has increased.

 

[Nigel Goodwin]

In the UK do people scream in a club?

Quite probably

My wife was down Chesterfield last Saturday (we have a few members here from that town), she was amazed to see a young girl 'out on the town' wearing nothing but a short teeshirt - not even underwear!. 13th of December, temperatures below freezing, and walking round mostly naked - what is the world coming to?.

 

[audioguru]

My wife was down Chesterfield last Saturday (we have a few members here from that town), she was amazed to see a young girl 'out on the town' wearing nothing but a short teeshirt - not even underwear!. 13th of December, temperatures below freezing, and walking round mostly naked - what is the world coming to?.

Yes.
Young ladies have tempted/teased guys since the beginning of time.

I was walking my dog in the park and found a completely naked young lady standing on a picnic table with her friends all around. She was dared to do it.

 

[Ridi_Ree]

Oh. You are making a simple circuit to replace the Disc Jockey who turns up the volume as the time gets later.

I don't think you will find a noisy train or jet airplane in a club so I don't know what your "filtering/weighing network" will be sensing. In the UK do people scream in a club? Dogs barking?

My car radio automatically turns up the volume when a certain speed is exceeded. It assumes that the background noise has increased.

Thnks for the really sarcy advice mate , would i need a rms detector for ignoring peaks in sound e,g glasses smashing? or would peak detector be better?

 

[audioguru]

Don't they play loud music continuously in a club? Then you won't be able to measure the noise level.

 

[Ridi_Ree]

Yeah the device will attach itself to the mixing desk and will have an inverse feed coming from the sound system to avoid self defeating, it will ignore the music and focus on the other noise

 

[audioguru]

The music coming through the air to your sound sensor will have a time delay and will have a completely different phase from the inverse feed, so the noise sensing won't work.

 

[Willbe]

Fellow "Electronicians", perhaps?

 

[Ridi_Ree]

Fellow "Electronicians", perhaps?

Oh my days, i can see this might have been a mistake

 

[Ridi_Ree]

The music coming through the air to your sound sensor will have a time delay and will have a completely different phase from the inverse feed, so the noise sensing won't work.

It might be out of phase but i was planning on the design to recognise the similar wave forms

 

[audioguru]

It might be out of phase but i was planning on the design to recognise the similar wave forms

The feed makes a signal. A little while later the sound comes through the air. So delay the signal somehow. How many speakers will be producing a different length delay?

How "perfect" is the frequency response of the speakers and the angle that your noise sensor will receive it at?

Do you have a computer with a custom program to compare the delayed feed to the sensed sounds?

 

[bigkim100]

Yes.
Young ladies have tempted/teased guys since the beginning of time.

I was walking my dog in the park and found a completely naked young lady standing on a picnic table with her friends all around. She was dared to do it.

Hell Ill get naked if anyone dares me to do it on here.
The effect that a hairy 6ft7 3oo lb guy will have may be a bit different tho.

I will also accept donations to have me keep my clothes on as well.

 

[Willbe]

6ft7

You would have been exempt from the draft in the U.S., when there was a draft.