Hi I'd like to add a few notes...
when using speaker entities, there is a key of s_waitfortrigger with this key you set the value to 1 so that when its targeted (connected to a trigger) it will fire when activated or else it will 'always be on or it will play once and will make you wonder,waitfortrigger is an important key to use with speakers, and if you want your sound to loop use the key s_looping and val set to 1.
And if you look above in the editor toolbar you'll see two little icons with a speaker shape
these will show your sound radius visually once you have a sound shader selected from the entity inspector sound selection.
Here's an important fact many don't know firsthand especially for new artists using D3edit.
sound in volume is measured in -db (decibels) so 0 is full volume and -3 is -3db in volume using the s_volume key you would enter a minus value to reduce the volume of the sound your using if it's too loud.
max distance and min distance are important too when having your sound reach certain areas, the little speaker icons at the top are useful for showing that.
and s_global key and val: 1 makes the sound carry through the whole level no matter where you are.
most val entries are mostly a one or zero, one being 'ON and zero being 'OFF but there are other keys that use other values with different numbers.
These are just some things I wanted to point out about using speakers and sound.
and when making your own custom sounds you just need to simply write up a sndshd file to have it show up in the editor, myself I find that .ogg files work best rather than .wavs, and .wavs take up lots of space to where .ogg is a nice small file. you can use almost any program to make .ogg files but one in particular I like using for sound editing is goldwave. I'm not sure if audacity saves as .ogg but anyways, I just wanted to share some things I've learned with ya and hope that helps somewhat.
for triggers there are two ways to make one one is dragging a brush on screen and with it still selected right click and select trigger/trigger once or make a brush and with it selected using the entity inspector choose trigger once in the drop down selection and hit create, that should work.
and for lights there is a key of ..key: start off ....then give it a val of 1 to start in the off position before it's triggered, or the opposite with zero for a value and when triggered will turn off when triggered. again do take some time to look at entity properties to understand more of what they can do.
have a good one and more importantly have fun!