Horn (acoustic)
（重定向自Exponential horn）
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![A patent horn loudspeaker](/Images/godic/202501/12/Electrovoice-constant-directivity-horn-19754511.jpg")
![Male mole cricket in singing position in burrow. The burrow is shaped as a double exponential horn with bulb.](/Images/godic/202501/12/Mole_cricket_burrow4511.png")
An acoustic horn or waveguide is a tapered sound guide designed to provide an acoustic impedance match between a sound source and free air. This has the effect of maximizing the efficiency with which sound waves from the particular source are transferred to the air. Conversely, a horn can be used at the receiving end to optimize the transfer of sound from the air to a receiver.