raspberry distance sensor + bluetooth audio, example here: https://www.whiletrue.it/it/raspberry-pi-riprodurre-audio-via-bluetooth-se-qualcuno-si-avvicina/

pi_distance_bluetooth.py

# VARIABLES
bluetooth_mac_address = "AA:BB:CC:DD:EE:FF"
# Audio start and stop distance, expressed in cm
distance_audio_start = 20
distance_audio_stop = 50
audio_tracks = [
    "AUDIOFILE1.mp3",
    "AUDIOFILE2.mp3"
]
GPIO_TRIGGER = 40
GPIO_ECHO = 38

# LIBRARIES
import RPi.GPIO as GPIO
import os, random, time
from pygame import mixer

def setup():
    if (bluetooth_mac_address != ""):
        # Start Pulseaudio, connect to Bluetooth device and set it as playback default
        time.sleep(5)
        os.system("pulseaudio --start")
        time.sleep(5)
        os.system('echo "connect ' + bluetooth_mac_address + '" | bluetoothctl')
        time.sleep(5)
        os.system("pacmd set-default-sink 1")
        time.sleep(5)

    # Init audio mixer
    mixer.init()
    mixer.set_num_channels(1)

    # Set GPIO Mode and Pins
    GPIO.setmode(GPIO.BOARD)
    GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
    GPIO.setup(GPIO_ECHO, GPIO.IN)


def play_file():
    filename = random.choice(audio_tracks)

    if (mixer.music.get_busy() == False):
        print ("Playing " + filename )
        mixer.music.load(filename)
        mixer.music.play()


def distance():
    # Set Trigger to HIGH
    GPIO.output(GPIO_TRIGGER, True)

    # Set Trigger after 0.01ms to LOW
    time.sleep(0.00001)
    GPIO.output(GPIO_TRIGGER, False)

    StartTime = time.time()
    StopTime = time.time()

    # Save StartTime
    while GPIO.input(GPIO_ECHO) == 0:
        StartTime = time.time()

    # Save time of arrival
    while GPIO.input(GPIO_ECHO) == 1:
        StopTime = time.time()

    # Time difference between start and arrival
    TimeElapsed = StopTime - StartTime
    # Multiply with the sonic speed (34300 cm/s)
    # and divide by 2, because there and back
    distance = (TimeElapsed * 34300) / 2

    return distance


if __name__ == '__main__':
    print ("Starting ...")
    try:
        setup()
        while True:
            # Measure distance twice, use the smaller value
            time.sleep(1)
            dist1 = distance()
            time.sleep(1)
            dist2 = distance()
            dist = min(dist1, dist2)
            print ("Distance = %.1f cm" % dist)

            if (dist < distance_audio_start):
                play_file()
            elif (mixer.music.get_busy() and dist > distance_audio_stop):
                print ("Audio stop")
                mixer.music.fadeout(2000)
                time.sleep(1)

    # Reset by pressing CTRL + C
    except KeyboardInterrupt:
        print("Stopped by user")
        GPIO.cleanup()