Microphone V2

This object lets you access the built-in microphone available on the micro:bit V2. It can be used to respond to sound. The microphone input is located on the front of the board alongside a microphone activity LED, which is lit when the microphone is in use.

Sound events

The microphone can respond to a pre-defined set of sound events that are based on the amplitude and wavelength of the sound.

These sound events are represented by instances of the SoundEvent class, accessible via variables in microbit.SoundEvent:

microbit.SoundEvent.QUIET: Represents the transition of sound events, from loud to quiet like speaking or background music.
microbit.SoundEvent.LOUD: Represents the transition of sound events, from quiet to loud like clapping or shouting.

Functions

microbit.microphone.current_event()

Get the last recorded sound event.

Returns:: The event, SoundEvent('loud') or SoundEvent('quiet').

microbit.microphone.was_event(event)

Check if a sound was heard at least once since the last call.

This call clears the sound history before returning.

Parameters:: event – The event to check for, such as SoundEvent.LOUD or SoundEvent.QUIET.
Returns:: True if sound was heard at least once since the last call, otherwise False.

microbit.microphone.is_event(event)

Check the most recent sound event detected.

This call does not clear the sound event history.

Parameters:: event – The event to check for, such as SoundEvent.LOUD or SoundEvent.QUIET
Returns:: True if sound was the most recent heard, False otherwise.

microbit.microphone.get_events()

Get the sound event history as a tuple.

This call clears the sound history before returning.

Returns:: A tuple of the event history with the most recent event last.

microbit.microphone.set_threshold(event, value)

Set the threshold for a sound event.

The SoundEvent.LOUD event will be triggered when the sound level crosses this threshold upwards (from “quiet” to “loud”), and SoundEvent.QUIET event is triggered when crossing the threshold downwards (from “loud” to “quiet”).

If the SoundEvent.LOUD value set is lower than SoundEvent.QUIET, then “quiet” threshold will be decreased to one unit below the “loud” threshold. If the SoundEvent.QUIET value is set higher than SoundEvent.LOUD, then the “loud” threshold will be set one unit above.

Parameters:

event – A sound event, such as SoundEvent.LOUD or SoundEvent.QUIET.
value – The threshold level in the range 0-255. Values outside this range will be clamped.

microbit.microphone.sound_level()

Get the sound pressure level.

Returns:: A representation of the sound pressure level in the range 0 to 255.

microbit.microphone.sound_level_db()

Returns:: A representation of the sound pressure level in decibels (dB) in the range of 52.0 to 110.0 dB.

Example

An example that runs through some of the functions of the microphone API:

# Basic test for microphone.  This test should update the display when
# Button A is pressed and a loud or quiet sound *is* heard, printing the
# results. On Button B this test should update the display when a loud or
# quiet sound *was* heard, printing the results. On shake this should print
# the last sounds heard, you should try this test whilst making a loud sound
# and a quiet one before you shake.

from microbit import *

display.clear()
sound = microphone.current_event()

while True:
    if button_a.is_pressed():
        if microphone.current_event() == SoundEvent.LOUD:
            display.show(Image.SQUARE)
            uart.write('isLoud\n')
        elif microphone.current_event() == SoundEvent.QUIET:
            display.show(Image.SQUARE_SMALL)
            uart.write('isQuiet\n')
        sleep(500)
    display.clear()
    if button_b.is_pressed():
        if microphone.was_event(SoundEvent.LOUD):
            display.show(Image.SQUARE)
            uart.write('wasLoud\n')
        elif microphone.was_event(SoundEvent.QUIET):
            display.show(Image.SQUARE_SMALL)
            uart.write('wasQuiet\n')
        else:
            display.clear()
        sleep(500)
    display.clear()
    if accelerometer.was_gesture('shake'):
        sounds = microphone.get_events()
        soundLevel = microphone.sound_level()
        print(soundLevel)
        for sound in sounds:
            if sound == SoundEvent.LOUD:
                display.show(Image.SQUARE)
            elif sound == SoundEvent.QUIET:
                display.show(Image.SQUARE_SMALL)
            else:
                display.clear()
            print(sound)
            sleep(500)