In a home studio setting, it can be a trial to get the "right" sound. There is always room ambiance, unexpected noises, and even electrical interference to contend with with recording. Things are a little better when designing sound or music exclusively on your PC, but you still better make sure you have the right gear to ensure things sound the way you want them to sound.
Let me begin with an anecdote to demonstrate the importance of good sound gear.
A while back, I used my laptop to remix a MIDI song by a good friend of mine. Using my laptop speakers to monitor the sound, I got everything perfect - or so I thought. I used awesome sound fonts, some effects, and even a virtual instrument or two. I mixed the tracks down, put it into MP3 format, and e-mailed it to the original author.
When he got back to me, he said he experienced some really bad distortion and buzzing, and couldn't even get half-way through the song before he turned it off. I was confused, to say the least. After all, it sounded fine on my laptop, and even on an ancient pair of headphones I had lying around. I couldn't understand what was going on.
A while later, I spent a little money on some good - but pretty inexpensive - headphones. They were $25 Sennheiser HD 202 cans. Despite the low price, I noticed that all my ripped CD music sounded much better - the definition was more clear, and it was like hearing the songs again for the first time. Out of curiosity, I played that old MIDI song I remastered as an audio file and listened to it through my new phones.
Ouch. My ears nearly bled. The bass was far, far too deep. Fat bass is good, but only to a point... and the bass in my remix went well beyond that point.
The weak link was my monitoring equipment. The older headphones and the laptop speakers have nearly no bass reflex, so when I listened to the bass output of my music, it sounded like it wasn't there until I turned it up really, really high. In fact, I had the bass maxed out in my mix just to be able to tell it was there. The moral of the story: Never rely on laptop speakers or crappy headphones to monitor sound!
When recording or producing audio in the home studio, it is very, very important to use good headphones. You don't have to buy anything overly expensive, and you don't really need monitor speakers (your room will color the sound coming out anyway, and you want a more accurate monitoring method for home recording). In fact, those $25 headphones I bought turned out to be all I needed to tell my bass was horribly overdriven.
So, what do you look out for in headphones for the purpose of the home game development studio? It's pretty simple - you want a good frequency range.
Sound waves work like this: Sounds move in up-and-down waves. The faster the waves go up and down, the higher the frequency. The slower the waves go, the lower the frequency. Fast waves make treble, and slow waves make bass. Sound frequency, then, can be thought of as how frequent the sound wave goes from 0, to its peak, to its low, and back to 0. The number of times per second this happens is measured in hertz, or Hz.
When looking for the frequency range of a set of headphones, a good low range is 18Hz or lower. A good high end is around 20,000Hz (20kHz) or higher.
So, let's say you have one pair of headphones that has a frequency range between 25Hz and 10kHz. If you play a sound through these, and a bass sound wave that has a frequency of 22Hz moves through it... you won't hear it all. The headphone drivers in our example cans don't react to sound that low. This can cause you to do what I did and crank up the bass to compensate, and driving anyone with decent sound systems insane. On the other side of the coin, our example headphones won't respond to treble sounds that have a frequency of more than 10kHz.
There are other things to consider, of course. Some headphones can "color" the sound, by responding more heavily to bass to make songs sound more bass than they actually are (among other quirks). The best thing to do is to look for "monitor" or "studio" headphones. These are just headphones that try to color sound as little as possible. Though the accuracy may be better on one set than another, for composing game music, you don't necessarily have to go on safari to find the "perfect" set.
And, remember that just because a pair of headphones has a wide range, doesn't mean that the headphones can output that entire range at the same time. A heavily bass song can actually make the treble weaker, and vice versa. This is dynamic range. Electronics have a finite signal range that can be recorded and played back, so keep this in mind.
If you intend to design music for video games in a small setting, a good pair (or three) of headphones is a must. Never rely on inferior output to monitor your sound - a lot of consumer sound equipment have really poor bass response. To get the best results from a set of headphones, be sure to get some with a good bass and treble response, and be sure to read customer reviews and note the characteristics of different sets.
Do yourself and your gamers a favor and use good audio monitoring equipment. Your players will thank you for not exploding their subwoofers... or their ears.