voice echo problem!!!

[ibrar0]

i want to deploy big sound system in a hall, but there is a problem. the sound is producing echo to much. what will be the solution to this how to remove echo. either i have to use dsp(digital signal processor).

May be problem can be understood by following example, when we turn on louder of our mobile phone why the person on receiving end does'nt listen his voice through louder to again come in mic.(i mean wht is technology used in mobiles to remove echoing which created due to louder of mobile phones)????

 

[audioguru]

If the big hall has echoes then it has poor acoustics. DSP won't help.

Instead of only one or two high power speakers use many speakers at low power. Then a speaker is always close to a listener but the echo is far away and is very low level.

I used DSP echo cancellers in telephone and video conferencing systems. The DSP learned the echo pattern of a room and cancelled it from being transmitted back to the other end that sent the original signal. If a door opened in the room or something else changed the echo pattern then the DSP got lost and gain switching had to be used until the DSP learned the new echo pattern.
Most speakerphones use gain switching and a few also use DSP.

PA in a room is completely different. You cannot cancel the sound that is bouncing around the room.

 

[ibrar0]

Ok, i dont have so, much experience but in big halls mostly low level sound system fails, they(hall owners) hier big companies like sony,creative to build there sound system.they take too much cost near about 80 lacs some what up and down. so, what you think they use dsp in there sound system or the technique u mentioned above????

 

[audioguru]

DSP doesn't cancel echoes in a room. It cancels echoes from being transmitted to another location when a single microphone is used.

A hockey arena has many bad echoes. Cheap sound systems hang some very loud speakers in the center then the sound is very bad with many echoes. Good sound systems have many speakers in front of the people at low level. Then the speakers are close to the people and the sound is clear. But the echoes are far away and are at a very low level.

Using directional speakers also reduces echoes.

I have seen sound absorbing material on walls of school gyms that absorbs echoes. Concert halls are designed with good acoustics and also use absorbent material to control echoes.

 

[ibrar0]

Thnks, I used DSP echo cancellers in telephone and video conferencing systems.
I want to learn use of dsp as a biggner, i have my experience in microcontroller programming,(my programming is good). can you suggest the best tutor of dsp which dsp i should use as a biggner and programmer means the basic necessities to learn use of dsp (sorry for bad english)

 

[audioguru]

Texas Instruments have some very good articles about DSP echo cancellers.