loop of fast and slow random audio

beepy_boopy.py

import time
import random
import array
import math
import audiocore
import board
import digitalio
import audiobusio

audio = audiobusio.I2SOut(board.GP10, board.GP11, board.GP9)
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT

slow_threshold = 0.2
fast_threshold = 0.001
sleep_num = 0.1
speeding_up = True
while True:

    if speeding_up:
        sleep_num = round((sleep_num - 0.001), 3)
    else:
        sleep_num = round((sleep_num + 0.001), 3)

    if (sleep_num == fast_threshold):
        speeding_up = False
    elif (sleep_num == slow_threshold):
        speeding_up = True
    else:
        pass

    tone_volume = 0.25 
    frequency = random.randrange(220, 880, 1)
    length = 8000 // frequency
    sine_wave = array.array("h", [0] * length)
    for i in range(length):
        sine_wave[i] = int((math.sin(math.pi * 2 * i / length)) * tone_volume * (2 ** 15 - 1))
    sine_wave_sample = audiocore.RawSample(sine_wave)
    print(sleep_num)
    audio.play(sine_wave_sample, loop=True)
    led.value = False
    time.sleep(sleep_num)
    led.value = True
    audio.stop()