# 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!