# Thread: Electronics Project: Sound level meter with audio announcement for library

### Minimum Detectable Signal

The ability of a radar receiver to detect a weak echo signal is limited by the noise energy that occupies the same portion of the frequency spectrum as does the signal energy. The weakest signal the receiver can detect is called the minimum detectable signal Read this topic
1. ## Electronics Project: Sound level meter with audio announcement for library

Abstract--

As our final year project we are going to present “Sound level meter with voice announcement”. Our project measure sound pressure level and display it on 16*2 LCD. The project is also connected to Audio announcement circuit. So our project continuously measure sound pressure, and compare with critical noise level set using microcontroller programming. If sound noise pressure exceed from set value, voice announcement circuit start play, giving warning massage. This project can be very useful for the college library and everywhere where noise level matter.

A basic sound level meter shows the sound pressure level with different frequency weighting and with different time integration that are used for noise assessment. In almost all countries, the use of A-frequency-weighting is mandated for protection of workers against noise induced deafness.

The standard sound level meter is more correctly called an ‘exponentially averaging sound level meter’ as the AC signal from microphone is converted into DC by a root-mean square circuit and thus I must have a time constant of integration; today, referred to as time weighting. The output of RMS circuit is linear in voltage and passed through a logarithm circuit to give a linear readout in decibels. It follow that decibels is not a unit but simply a dimensionless ratio-in case, the ratio of two pressures. The decibel is a logarithmic unit used to describe a ratio. The ratio may be power, sound pressure, voltage,

intensity, etc. Not at all frequency is equally loud. This is because human ear does not respond equally to all frequencies. Our ear much sensitive to sound in frequency range of 1 KHz to 4 KHz. So sound meter are usually fitted with a filter whose response to frequency is almost like that of the human ear. If the A-weighting filter is used, the sound pressure level is given in dB unit.

2. ## Re: Electronics Project: Sound level meter with audio announcement for library

kam karega na , karega to banata hu

3. ## Re: Electronics Project: Sound level meter with audio announcement for library

Originally Posted by naresh170690
kam karega na , karega to banata hu
[MENTION=21500]naresh170690[/MENTION]- arre you are a FaaDoO Engineer!

even if it doesnt work, you'll find a way out..!

4. ## Re: Electronics Project: Sound level meter with audio announcement for library

I'm interested in this topic . Pls send ref: also.

5. ## Re: Electronics Project: Sound level meter with audio announcement for library

thanks alot ........i've got my major project......

7. ## Re: Electronics Project: Sound level meter with audio announcement for library

the pdf does not contain the programming as mentioned................plz help!!!!!

---------- Post added at 04:50 PM ---------- Previous post was at 04:49 PM ----------

also the pdf does not contain complete info
on some pages there are only topics without any content................

8. ## Re: Electronics Project: Sound level meter with audio announcement for library

this looks good.

9. ## Re: Electronics Project: Sound level meter with audio announcement for library

pls send details of this project on sonawane.sayali1990@rediffmail.com

10. ## Re: Electronics Project: Sound level meter with audio announcement for library

i want to know more about the working of audio annoucement circuit

11. ## Re: Electronics Project: Sound level meter with audio announcement for library

this is awsum dude..u made my mind 2 learn pic also..actualy i only had knwldge abt 8051..nw i hv cmplete command ovr microcontrollers..
n thanx fr this report man..

12. ## Re: Electronics Project: Sound level meter with audio announcement for library

This is a nice project , I am interested to work on this can u give me details of this .....

13. ## Re: Electronics Project: Sound level meter with audio announcement for library

Can I get the coding of the project, "Sound-level-meter-with-audio-announcement-for-library"... Plzz its urgent

14. ## Re: Electronics Project: Sound level meter with audio announcement for library

Sir,i want details of this project like programing, stimulated circuit etc.urgently.thank u.My email add. garadesujeet[MENTION=183148]gmail[/MENTION].com

15. ## Re: Electronics Project: Sound level meter with audio announcement for library

Can I get the coding of the project plz send at giteshsahu98[MENTION=183148]gmail[/MENTION].com

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