Simulation of channels volume desynchronization

#!/usr/bin/env bash

# set 100% for all channels;  don't print STDOUT;
amixer -D pulse sset Master 100% 1>/dev/null

# print result
echo -ne "\nbefore:\n"
amixer

# prepare for nice comparation in `vimdiff`
amixer_a=$(echo "before:"; amixer)

# 100 times parallel decrase volume for all channels by 1%
# don't print STDOUT; don't print STDERR
# it's working also with, for example 1%-, but
# I choose changing by number according to
# https://wiki.archlinux.org/index.php/PulseAudio/Troubleshooting#Volume_adjustment_does_not_work_properly
for x in {1..100}
do
    ( amixer -D pulse sset Master 700- 1>/dev/null 2>/dev/null ) &
done

# wait for for in ugly way... but KISS, that's only simulation ;)
sleep 3s

# print result
echo -ne "\nafter:\n"
amixer

# prepare for nice comparation in `vimdiff`
amixer_b=$(echo "after:"; amixer)

# nice comparation in `vimdiff`
vimdiff <(echo "$amixer_a") <(echo "$amixer_b")