Electromechanical Conversion
When an audio current flows through the horn loudspeaker's voice coil, the coil is situated within a magnetic field generated by a permanent magnet. According to the principle of Ampère's force, a current-carrying conductor in a magnetic field experiences a force; the voice coil generates a magnetic field that fluctuates with the audio current. This field interacts with the permanent magnet's magnetic field, causing the voice coil to vibrate back and forth along its axis, thereby converting the electrical signal into mechanical vibration.
Mechano-acoustic Conversion
The vibration of the voice coil drives the attached diaphragm to vibrate; this diaphragm vibration agitates the surrounding air, generating sound waves. However, sound radiated directly from the diaphragm is inefficient and has poor directivity.
The Role of the Horn
The unique feature of a horn loudspeaker is its horn structure. The horn serves to collect and amplify the sound waves produced by the diaphragm while altering their propagation direction and characteristics. The horn typically features a shape that gradually transitions from narrow to wide; this geometry allows sound waves to expand progressively within the horn, minimizing reflection and scattering while enhancing propagation efficiency and directivity. Ultimately, it effectively radiates sound waves into the surrounding space, enabling the sound to travel greater distances and maintain high sound pressure in a specific direction.