Playing an wav audio file on button press with "Feather RP2040 Prop-Maker" (update Debounce)

code.py

import supervisor
supervisor.set_next_code_file(None, reload_on_error=True)

import board
import audiocore
import audiobusio
import audiomixer
from digitalio import DigitalInOut, Direction, Pull

from adafruit_debouncer import Debouncer

# enable external power pin to provides power to the external components
external_power = DigitalInOut(board.EXTERNAL_POWER)
external_power.direction = Direction.OUTPUT
external_power.value = True

# i2s playback
level_play = 0.5
wave_file = open("Merry-Xmas-Piano.wav", "rb")
wave = audiocore.WaveFile(wave_file)
audio = audiobusio.I2SOut(board.I2S_BIT_CLOCK, board.I2S_WORD_SELECT, board.I2S_DATA)
mixer = audiomixer.Mixer(voice_count=1, sample_rate=22050, channel_count=1, bits_per_sample=16, samples_signed=True)
mixer.voice[0].level = 0
audio.play(mixer)

# servo control
play_ringtone = False

# boot button
switch = DigitalInOut(board.BUTTON)
switch.direction = Direction.INPUT
switch.pull = Pull.UP

# external button
switch_ext_ = DigitalInOut(board.EXTERNAL_BUTTON)
switch_ext_.direction = Direction.INPUT
switch_ext_.pull = Pull.UP

# Make the external switch a debounced switch with minimum 50 ms
switch_ext = Debouncer(switch_ext_, interval=0.05)

switch_state = False

while True:
    if play_ringtone:
        if not(mixer.voice[0].playing):
            play_ringtone = False
            mixer.voice[0].level = 0.0
            print("Stopped playing")
    else:
        if (not switch.value or not switch_ext.value) and switch_state is False:
            play_ringtone = True
            switch_state = True
            mixer.voice[0].play(wave, loop=False)
            mixer.voice[0].level = level_play
            print("Starting playing")
    if (switch.value or switch_ext.value) and switch_state is True:
        switch_state = False

On multiple occasion, the Xmas sound started, so I added a 50ms debounce on the external button.
I don't know yet how effective it is, should it be shorter or longer???