[Unit]
Description=Beep glide on poweron/poweroff

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/bin/bash -c 'for i in $(seq 100  50 1500); do beep -f $i -l 25; done'
ExecStop=/bin/bash -c 'for i in $(seq 1500 -50 100); do beep -f $i -l 25; done'

[Install]
WantedBy=multi-user.target