in my project the tip input is connected to the A0 input,
and read this signal input on the arduino.
You don't provide much information
The Arduino input shouldn't be "floating". It should be pulled-up, pulled-down, or in the case of audio it should normally be biased at about 2.5V so the audio signal can swing positive and negative around the bias.
Audio signals are AC (they go positive and negative). The Arduino can't read the negative half of the waveform and it can actually be damaged by negative voltages.
There is a bias circuit at the bottom of this post.
You may know this already but since you are sampling a wave your readings will "look random", even with a constant tone. But, you will get bigger deviations from the bias with louder sounds.
The very big problem here is that you have not said what you want to do with this audio signal once it is in the Arduino.Knowing that we could tell you what sort of interface you need and whether this is practical.
There is a way to use a diode. Take a look at the 2nd schematic here.D3 is for excess positive voltage so you can leave that one out.Resistor R1 should be between 1K & 10K for audio signals. (With a line-level signal use 10K. 1K is fine with headphone signal.)
Ideally, the diode should be a Schottky diode. There are already "small" protection diodes inside the ATmega chip. Schottky diodes have lower forward voltage than standard silicon diodes so that insures that all of the current goes through the external Schottky. Or if R1 is 10K Ohms, the internal diode alone would be OK. and you could just skip the external diode.
That circuit will "kill" the negative half of the signal
The pinout for a TRRS connector from a phone is NOT normally sleeve=ground as you might think.You need to read up on the various standards, modern phones are usually _CTIA_https://en.wikipedia.org/wiki/Phone_connector_(audio)#PDAs_and_mobile_phonesYou can get CTIA -> TRS adaptor cables if you're not interest in the microphone signal.
the idea of my project is to take the input to make a variation on a led strip (at the moment it's just a rgb led)for example:if the input is 100, the led will light up:
i still have the same problems since there is noise,