Sampling is one of the most powerful tools in modern music. Whether it is a looped bar from a song, commonly used in hip-hop, layered over beats; vocal samples, or even just a drum sample, it is a great way of making the music you want. It not only saves time recording an instrument that you don't have but also means you can access and morph sounds that aren't musical and incorporate them creatively into your music.
This is an older article which I have revisited and added more content to!
Samples, like with any sound designing, can be as complicated as you like. You could insert the raw sample into a song and use it from there or, you could open up all possibilities with it. Any noise can be musical if tweaked correctly, some sounds are already distinct notes, like a bird tweeting, others are more difficult, like a blender...
This video clip demonstrates why you should consider
literally everything as an instrument.
Just because a sound is noisy, or doesn't sound musical, I guarantee you it will have sound content that is golden for a song idea. You may need plugins to tweak it into something usable, as demonstrated above, but it will be the sound that could separate you from the rest. You just need to work on it.
I once sat in a bare room and realised it was very echo'y, I went about recording claps and bangs. In my DAW, I removed the initial sound so I only had the reverb tail and with heavy limiting, and pitch shifting, I got some filthy notes, that I would never have been able to make on a synth.
It's all about experimenting with the sound, you could easily make a song, by just sampling a couple of words. The "t" sound and the "b" sound are excellent for morphing into drums (snare and kick respectively), and by taking the vowel sounds of a word and re-sampling them you can have all sorts of notes and sounds making your instruments.
Samplers aren't the only destination for good samples, Vocoders are a must too. By using the odd samples as the modulator signal, you can change the sound of your synths drastically. It can be a very conspicuous sound effect, especially if the sample is really odd, or it can be really subtle - you can alter the dry/wet mixes in most good vocoders.
So in the grand quest of sound discovery, where would one look to get the best samples? The answer really is everywhere. Skrillex has been known to use lion and elephant roars/screams in his music. You can rip sounds and voices off Youtube or download sample packs (Google is your friend).
If you want to be more creative and unique, grab yourself a field mic and get recording your own sounds. With enough time, you could build a large collection and even sell it on/give it away free.
Of course sometimes you don't want the samples to be an instrument in the song. You may want rain and thunder samples for the background. You may want street noises, to give the impression you recorded a section on the street.
Consider how film sound engineers work, layering each ambient sound together to create a realistic representation of the setting. Same can be done in a song. Silence can be as jarring as bad noise and so if there is a quiet section of your song, perhaps just vocalist, you could add some barely audible noise. It would have to be appropriate but that's where the art of this comes in, finding something that's not out of place.
So go out now and record everything, download everything and, use everything in music.
FOOTNOTE: If this is a section of music production that interests you, I highly recommend the feature on Xfer Serum's ability to "sample" images and re-encode them into wavetables.