Lasersound

[Siddharth]

I have been thinking can sound(speech)be transmitted only in one direction without spreading to a particular point.

Ultrasound travels in one direction.So can audio be mixed with ultrasound so that the audio travels in one direction.

It can really help in loudspeakers.The sound will not spread hence the others (those not listening) will not be disturbed

It is like modulation.

Please do help.

[bogdan]

well, i have seen something like this.
you produce an ultrasound and modulate it in such a way that the human ear will hear as the sounds were at the correct frequency.
since you can make the ultrasound unidirectional, i think that this is the sollution.
still, making the sound perfectly directional is not possible since it is transmitted trough the air, so the nearby air vibrates along with the sound column and so the sound is transmitted in various directions, with lower intensity of course.

[Siddharth]

Could i get the circuit diagram for such an device.

Where have you seen it?

What was the maximum range of it ?

[hotwaterwizard]

Check out this Website for another Idea!

http://www.ee.vill.edu/ion/index.html

[audioguru]

Hotwaterwizard,
1) I saw an advertisment for an ultrasonic "sound beam" about 3 months ago but have lost the source. Apparently when the modulated beam hits an object (like a statue in a museum) then the sound demodulates and appears to originate from that object. Only people near the object can hear the sound without everybody being bothered like with a PA system today. Their biggest problem is to make the ultrasonic beam powerful enough because it is absorbed by the air and tweeters are fragile and low-power.
2) Plazma (flame) tweeters have been demonstrated for many years. They are very impractical.

[audioguru]

Siddhu and Hotwaterwizard,
I found (isn't Google great?) the link about "hypersonic sound" and their use an array of many ultrasonic transducers to create a plane (flat front not curved) wave that travels through the air without spreading-out. Another benefit of this system is that if you are in the beam then it demodulates when it hits you and the sound appears to come from INSIDE your head! But people who are nearby and not in the beam won't hear it.
They think of using it for translation: one language is beamed to a person or group and another language is beamed to a nearby person or group etc. The link is here:
http://www.reed-electronics.com/ednmag/contents/images/296500.pdf
 

[saileshkrishna]

hello siddhu,
                     ur idea of sending wave to exact position using ultrasonic is great.but i think there is very less probability of
mixing the sounds.even though u mix does the mixed one reach the target same as they are at the begining?
                      tell me clear idea of mixing.

[MP]

saileshkrishna, in fiber optics many signals are multiplexed together then sorted out at the other end by a few different methods. One method is digitizing the signal and demultiplexing at the other end. Another method is to use different color filters at the other end to separate the different wavelengths. I have not had experience with long range ultra sonic transmission, but I think that if you can get a good signal to go the distance, the method would be similar. Multiplexing and demultiplexing the different frequencies within this spectrum such as multiple channels.

MP

[Siddharth]

It seems that i will require some HI FI equipment to make such a device.Currently this out of the budget.If any one of you does make it do tell.

[Silent Jack]

I think that is a fascinating idea for a universal translator.