Sound sources are sound-generating transducers. The oldest sound transducer is the human voice with which speech, sounds or noises can be generated. To the mechanically working sound sources belong musical instruments with which sound images and sounds are produced.
Other sound sources with mechanical conversion include machines, vehicles, airplanes, etc. that do not produce harmonic sound, but disturbing noises. In addition, there are sound sources where the sound is generated by electrical actuators: Loudspeakers.
As far as the human voice is concerned, the acoustic sounds are produced by airflow that causes the vocal cords in the larynx to vibrate. The shaping of the sounds occurs through the mouth, pharynx and sinuses. The frequency range for human voices depends on gender and is about 1.5 to 2.5 octaves.
In musical instruments, sound is usually produced by pressure as in drums, activation of strings and resonance generation in a sound box as in stringed instruments, or by air pressure as in wind instruments. And in the case of electric actuators, i.e. loudspeakers, sound is generated by vibrations of a membrane and radiated to the environment.