Without Statemachine

import time
import board
import analogio
import digitalio
import neopixel
import random

# Register sensors
button = digitalio.DigitalInOut(board.D4)
button.direction = digitalio.Direction.INPUT

sound_sensor = analogio.AnalogIn(board.A0)

# Register LED
leds = neopixel.NeoPixel(board.D13, 1, auto_write=False, pixel_order=neopixel.GRBW)

# colors
color_off = (0,0,0,0)
color_on = (0,0,0,10)

leds.fill(color_off)
leds.show()

timer_mark = 0
timer_duration = 1

triggerd = False

while True:
    # Turn on LED
    if sound_sensor.value > 30000 and not triggerd:
        triggerd = True
        color = (random.randint(0,70),random.randint(0,70),random.randint(0,70),0)
        leds.fill(color)
        leds.show()
        timer_mark = time.monotonic()
        
    if sound_sensor.value < 30000 and triggerd:
        triggerd = False

    # Turn LED off
    if time.monotonic() - timer_mark >= timer_duration:
        leds.fill(color_off)
        leds.show()

With statemachine

import time
import board
import analogio
import digitalio
import neopixel
import random

# States
state_on_loud = 0
state_on_quiete = 1
state_off = 2
current_state = state_off


# Register sensors
sound_sensor = analogio.AnalogIn(board.A0)

# Register LED
leds = neopixel.NeoPixel(board.D13, 1, auto_write=False, pixel_order=neopixel.GRBW)

# colors
color_off = (0,0,0,0)
color_on = (0,0,0,10)

leds.fill(color_off)
leds.show()


timer_mark = 0
timer_duration = 1

color = None

triggered = False

while True:
    
    if current_state == state_off:
        # make sure the LED is off
        leds.fill(color_off)
        leds.show()
        # check if we should turn on
        if sound_sensor.value > 30000:
            # Start the timer!
            color = (random.randint(0,70),random.randint(0,70),random.randint(0,70),0)
            timer_mark = time.monotonic()
            current_state = state_on_loud       
    
    elif current_state == state_on_loud:
        leds.fill(color)
        leds.show()
        if time.monotonic() - timer_mark >= timer_duration:
            current_state = state_off
        elif sound_sensor.value < 25000:
            current_state = state_on_quiete
            
    elif current_state == state_on_quiete:
        leds.fill(color)
        leds.show()
        if time.monotonic() - timer_mark >= timer_duration:
            current_state = state_off
        elif sound_sensor.value > 30000:
            # Her start the timer!
            color = (random.randint(0,70),random.randint(0,70),random.randint(0,70),0)
            timer_mark = time.monotinic()
            current_state = state_on_loud