Lenovo ThinkPad T450
This article covers details pertaining to installing and configuring your Arch on Lenovo Thinkpad T450 laptop.
Check out the T450s wiki, as pretty much everything from there works on the T450: Lenovo ThinkPad T450s
Make sure to install alsa-utils/ or that it is installed.
See ALSA#Set the default sound card to set the default sound card to Intel PCH (speakers and headphones).
options snd_hda_intel index=1,0
make sure to reboot after these changes.
Rebinding Forward and Back Keys