Average noise level graph on Linux

Question

Using a laptop's microphone, I want a graph showing the level of noise during a certain period:

Noise needs to be sampled at a high rate and averaged over one minute or so. The output can be as simple as appending one line to a CSV file every minute.

Requirements:

• Runs on Linux
• Free, ideally open source
• Calculate average for a minute, not instant value
• Output to text file or image
• Bonus if it can "filter out" usual background noise, in order to better show anormal noise (a "training" could be required to specify what the usual background noise is)

Answer 1

You could always use the python soundmeter library.

• Runs on Linux
• Libre & FOSS
• You can average in a number of ways
• You can either output to a text file or use one of the plotting libraries
• Measures the RMS value.

Answer 2

I wrote this small bash script to do it:

#!/bin/bash
>data.txt
while true
do
  sox -t .wav "|arecord -d 1" -n stat 2>&1 | grep "RMS     amplitude" \
  | tr -d ' ' | cut -d ':' -f 2 >> data.txt
done

I takes the RMS every second and writes it to a text file.

A graph can be generated using this Gnuplot script (put it in a with graph.gnuplot file and run gnuplot graph.gnuplot):

set yrange [0:0.1]
set grid
set term png
set output 'graph.png'
plot 'data.txt' with line lt -1 lw 1