Teach you a simple method. Connect a trimming resistor (10K) to the horn connecting wire, connect the middle pin of the trimming resistor to the anode of the horn, and then connect the remaining two pins of the trimming resistor (only connect one of them). Connect one diode (1N4 148) to this pin for rectification, and then connect another diode.

Adjust the resistance value. When playing music, the LED will flash with the music.

If the same trimming resistor, diode and light emitting diode are connected in parallel, they can be combined into several groups, and then each group adjusts different resistance values to arrange the light emitting diodes in a row. When music is playing, the LEDs will change from bright to dark, and a row will flash with the music.

The circuit is done, so let's experiment first. If it doesn't light up when playing music, try to lower the resistance of the trimming resistor, or check whether the polarity of diode and LED is connected correctly.