For acoustic applications actually only 3 different types of magnet materials are used; in fact in quantitative order of Ferrite, NdFeB and AlNiCo. Since the 70s ferrite magnets have been used as inherent part of sound converters, which either must convince by low price or where installation space and weight do not play a major role. Those are the most representative ones. In the fields of automotive application meanwhile NdFeB magnets more and more prevailed due to their advantage of smaller size, higher strength and lower weight.
Thus they contribute to a significant weight reduction of the vehicle. Typical applications are loudspeakers, subwoofers and hands-free systems. Further those raw materials are more and more used for professional sonication, where smaller versions and lower weights are required. High remanent and high-temperature resistant magnet qualities also enable the usage in acoustic transducers at extreme conditions. Die excellent anti-corrosive characteristics and variously coating possibilities are other factors to guarantee a long lifetime and an optimal performance of the final product.
AlNiCo magnets are solely used for special loudspeakers, where music playback is rather used for vintage-similar characteristics (guitar-amps) or for modern broadband loudspeakers.