Assuming I have a microphone plugged into a computer is there an easy way to capture “Beep” type sounds (brief single tones) and categorize them by pitch and duration.
So that they could be feed into HA to trigger automations (again keyed by pitch and duration). A bit of googling shows that some combination of arecord and sox might be able to do the analysis of the sound.
However I am wondering if anyone else has already gone down this path / has something that is already usable?
I have it working.
This (Python) code is really terrible **, but it’s enough to prove the concept:
** - Need to spend some time making it look pretty.
import numpy as np
import sounddevice as sd
import paho.mqtt.client as mqtt
SAMPLE_RATE = 44100
CHUNK = 4096
# MQTT broker details
mqtt_broker = "ha.local"
mqtt_port = 1883
mqtt_username = "dtrott"
mqtt_password = "my_password"
topic = "test/topic"
client = mqtt.Client(mqtt.CallbackAPIVersion.VERSION2)
client.username_pw_set(mqtt_username, mqtt_password)
client.connect(mqtt_broker, mqtt_port, 60)
client.loop_start()
detected = False
sent_detected = False
def detect_beep(indata, frames, time, status):
global detected
global sent_detected
audio = indata[:, 0]
fft = np.fft.rfft(audio)
freqs = np.fft.rfftfreq(len(audio), 1 / SAMPLE_RATE)
magnitude = np.abs(fft)
low = max(magnitude[351:361]);
detect = max(magnitude[371:373])
high = max(magnitude[381:600]);
dd = detect * 0.5
detected = detect > 3 and low < dd and high < dd
if detected != sent_detected:
payload = "on" if detected else "off"
client.publish(topic, payload)
sent_detected = detected
def process_audio():
with sd.InputStream(callback=detect_beep,
channels=1,
samplerate=SAMPLE_RATE,
blocksize=CHUNK):
input("Listening... Press Enter to stop\n")
process_audio()
client.loop_stop()
client.disconnect()
How it Works
I am creating three ranges:
The “detection” range - the frequency I am looking for.
A “low” range below the frequency I am looking for.
A “high” range above the target frequency.
If I get a signal in the target range, above an arbitrary threshold (3 in this case) and the target signal is 3 dB’s clear of the low and high ranges then I consider that a detection.
I update an MQTT topic with the detection state whenever it changes - hence HA can use that topic to trigger automations.
