aplay command get mute when other process has sound

I am a beginner for Ubuntu developing.My Ubuntu version is Lubuntu 22.04 for aarch64.

I added a .py script like this;

import evdevimport os#symlink pathdevice_path = '/dev/input/by-id/usb-eGalax_Inc._USB_TouchController-event-mouse'#wav filewav_file = '/usr/local/autobase/Warn.wav'def play_wav():    os.system(f'aplay {wav_file}')def main():    try:        #open the device        device = evdev.InputDevice(device_path)        for event in device.read_loop():            #check BTN_TOUCH            if event.type == evdev.ecodes.EV_KEY and event.code == evdev.ecodes.BTN_TOUCH and event.value == 1:                print(" play !")                play_wav()    except Exception as e:        print(f"Error: {e}")if __name__ == "__main__":    main()

Then, I added this .py script as a systemctl service to run it at the background whwnever I get an event from the touchscreen, which has value ==1 .

It works well, however, the problem is playing wav file getg mute when I run other processes with sound.For example, if I run YouTube video playing wav gets mute.And, if I run the alsamixer to control the wav, playing wav gets mute.Then, if I stop playing sound or quit the process, it returns to play wav.

I checked it with systemctl -status, but it says "active".What would be the problem?Please help me.

+Plus,Even I make the volume of alsamixer mute, this service keep making wav file with certain volume.Isn't it related to alsamixer?