Ultrasonic horn(transmitter and receiver)

Using Arduino Sensors
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I have been trying on my engineering project for achieving noiseless horn using ultrasonic sounds.I knew nothing about how to do and where to start.basically,i had this idea of having two horns.One is a normal horn that will be activated when we honk it for a specified period and the ultrasonic horn part comes otherwise(for a single press).
Could anyone of you help me how to approach it(program part).I have some circuits from previous blogs by name ultrasonic transmitter and receiver.Also i am not familiar with arduino at all.Transmitter must be operated at frequencies over 20khz,receiver must be capable of sensing the transmitted signal from transducer(angle is not under consideration).

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Sounds easy enough.

Which horns are you using and how are they powered?

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How noiseless do you want the ultrasonic horn to be? A tuned resonant transducer is less likely to make
an audible click compare to a broadband tweeter, which in practice means using 40kHz tuned
tx and rx pair of transducers. They are highly directional.

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