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+# Raspberry Pi white noise machine
+
+September 19, 2021
+
+A white noise machine can help find sleep or mask ambient noise or even tinnitus. It can also be used to muffle conversation from potential eavesdroppers. I wanted to experiment with a white noise machine for sleep purposes so I decided to build one with a Raspberry Pi I had lying around.
+
+For this you will need:
+
+* A Raspberry Pi equipped with a jack port and an OS installed (I used a Pi 3B with Raspbian OS)
+* Speakers connected to the Pi
+
+Actually a Pi 3 is a bit overkill for this. I have a Pi Zero lying around that could fit the bill except it needs a USB dongle to connect speakers and I don't have such a dongle.
+
+## Preparing the white noise
+
+First you need to find a white noise sample, preferably a long one. I chose to extract the sound from a 3 hour long YouTube video of a waterfall. Of course, choose what suits you. If you want to extract the sound from a YouTube video, you could use one of the many online tools but I won't recommend that to you. Instead, you can use [youtube-dl](https://github.com/ytdl-org/youtube-dl):
+
+	$ youtube-dl -x --audio-format mp3 https://www.youtube.com/watch?v=dQw4w9WgXcQ
+
+Some explanations for the options used:
+
+* `-x` asks youtube-dl to extract the audio from the video. As stated in youtube-dl's help, ffmpeg or avconv is required for this
+* `--audio-format` should be self-explanatory
+
+## Creating a white noise service
+
+Next we are going to create a service to play the white noise automatically at system startup. My Raspberry Pi is running raspbian so systemd is used to manage services. Create a `/etc/systemd/system/whitenoise.service` file with the following contents:
+
+	[Unit]
+	Description=White noise machine
+	StartLimitIntervalSec=0
+
+	[Service]
+	Type=simple
+	Restart=never
+	User=pi
+	ExecStart=mpg123 --loop /home/pi/whitenoise.mp3
+
+	[Install]
+	WantedBy=multi-user.target
+
+You should adjust your username and path to the file. I used [mpg123](https://mpg123.org/) because it's the simplest and lightest audio player I could find. Its loop option is handy to keep playing infinitely. It needs to be installed:
+
+	# apt install mpg123
+
+## Auto start, auto stop
+
+To start automatically the service on system startup, you just need to enable the service on startup:
+
+	# systemctl enable whitenoise
+
+To stop it, you can use a cron job set at the time you want it to stop:
+
+	55 6 * * * sudo systemctl stop whitenoise
+
+This will stop the white noise at 6:55am. And that's it! Enjoy your homemade white noise machine!