There are many types of speakers, which can be divided into electric type (ie moving coil type), electrostatic type (ie capacitive type), electromagnetic type (ie reed type), piezoelectric type (ie crystal type), etc. according to their transducing principles. The latter two are mostly used in rural cable broadcasting networks; they can be divided into low frequency speakers, intermediate frequency speakers, and high frequency speakers according to the frequency range, which are often used as combined speakers in the speakers.
According to the conversion mechanism and structure, the split coil type (electric type), capacitive type (electrostatic type), piezoelectric type (crystal or ceramic), electromagnetic type (pressure spring type), electric ion type and pneumatic type speaker, etc. The speaker has the advantages of good electroacoustic performance, firm structure and low cost, and is widely used;
According to the sound radiation material, the paper basin type, the horn type and the diaphragm type; according to the shape of the paper cone, the circle, the oval shape, the double paper cone and the rubber folding ring; according to the working frequency, the bass, the middle sound, the high sound, and some are divided into Recorder-specific, TV-specific, normal and high-fidelity speakers; low-impedance and high-impedance by voice coil impedance; direct-spoke and ambient sound according to the effect.
Speakers are divided into built-in speakers and external speakers, while external speakers are commonly referred to as speakers. The built-in speaker means that the MP4 player has a built-in speaker, so that the user can listen to the sound of the MP4 player through the headphone jack or through the built-in speaker. The MP4 player with built-in speaker eliminates the need for an external speaker and avoids the inconvenience of wearing a headset for a long time.