By definition, an acoustic musical instrument is one whose sound is not electronically enhanced or modified in any way.
The sound produced from an acoustic string instrument, such as an acoustic cello, resonates solely from the sound waves released into the body of the instrument during a string’s vibration.
An electric cello on the other hand, requires the electronic amplification of the instrument in order for it to produce audible sound. If you’ve ever played an electric cello without plugging it into an amplifier first, you know that the sound is barely audible and muffled. Some people believe there is no difference in sound quality between an acoustic cello and an electronic cello that is plugged into an amplifier.