A horn seems to amplify in both directions: as an old hearing aid, or old gramophone. How?
Before electronics, a large horn could be used as a hearing aid: the small end was placed at the ear, and the large end pointed towards the sound source. A similar horn was used in a gramophone: the small end was connected to the needle, and sound radiated from the large end. Yes, the horn works in both cases and I can understand why you say that it amplifies in both directions. First, however, let’s define amplification. An electronic amplifier takes an electrical signal with low power as input, and outputs a signal with high power.
