Food isn't the only thing best left unprocessed; the best EVP evidence is also 100% natural. There are several sound editing/processing programs available but, by far, the program most overused and misused by the amateur ghost hunter crowd is Audacity. Like most tools used in paranormal investigation, it wasn't developed specifically for that purpose. Nonetheless, while a competent program, its main attraction is that it's available as a free download.
There is almost no reason to use software such as Audacity when attempting to discern whether you've captured a legitimate EVP. Why? Because the 'voices' are either there, or they're not. If you feel such a program is necessary, it's time to step up to a higher-quality digital recorder. Cheap, inexpensive recorders have cheap, inexpensive circuitry. The result is an entire feast of digital noise and artifacts, along with limited information recorded in a 'lossy', compressed format, recorded at a low sample rate. The problem is, with software such as Audacity, you really can make something out of nothing. And if you use a cheap recorder, nothing is basically what you have to work with; very limited digital information. Digital information is digital information, regardless of device or application. Think of it in terms of a digital camera: if you take a photo at a lower pixel resolution, you cannot enlarge that photo as much as one taken at a higher resolution without loosing clarity. The reason? There is less digital information in the lower resolution photo; fewer ones and zeros to begin with. The same holds true for digital audio. The end result? Twinkies. Yes, Twinkies. The ultimate in processed food, almost nothing in Twinkies is real, although they look real. They're artificial, man-made concoctions, originally developed in a food chemistry lab. Damn, but they certainly do look like something your grandmother lovingly baked in her oven, don't they? And that limited, processed tidbit of digital nothingness really does sound like a "Yes" or "No" response to your question, doesn't it? Yes, it may sound real. And yes, you may even be convinced that it is real. But what you end up with is not real. It's just processed and manufactured; nothing more than an audio version of Twinkies.
The solution to your unhealthy EVP lifestyle? Buy a good digital recorder. Like anything else, you can spend a fortune. And, like anything else, you don't have to. Many can be found in the $100-$300 price range; the main difference between the two extremes being features, not practical recording quality. The important specs? Look for one that can record audio as an uncompressed WAV file (avoid MP3 recording because of loss and compression inherent in the format), A 44 or 96 kbps (kilobit per second) sample rate, and 24-bit A/D (analog to digital) conversion. Always record at the highest audio quality setting that your recorder offers (which is usually 44 or 96 kbps/24-bit A/D conversion). Don't get too caught up in the name game; unless you have a brand preference, any recorder meeting these specs will be fine to record EVP. Your main consideration should be price and features, remembering that many advertised features will be little, if ever, used. Be certain the recorder can download files to your computer; nearly all but the least expensive now have that capability. One often-overlooked but extremely important consideration are the controls. Are the buttons too small? Too easy to press one button when you meant to push another? That's the unfortunate downside of downsizing. How easy is it to negotiate the menu? Check some online reviews, as that aspect will almost always be discussed. One recorder I often use, the DAS RT-EVP, makes awesome recordings, but is a real pain in the ass in that regard. The menu is unnecessarily cumbersome, which is especially irritating and problematic in the locations and conditions paranormal investigators often find themselves. On the positive side for paranormal investigators, it does seem to have been designed to be fairly immune to handling noise from the case, and does not require a windscreen when used outdoors as do other competing recorders.
Okay, you're ready to take a shot at recording an EVP. What to do? If applicable with your recorder, set the the microphone sensitivity to "High". Forget what you've seen on TV and avoid hand-holding the recorder, as the internal microphones are usually so sensitive that even the slightest hand movement against the case will be audible. The best method is to attach the recorder to a tripod or, at the very least, positioning it on a steady surface. To avoid low frequency vibration if using a hard surface, I've found that placing a computer mouse pad under the recorder helps to isolate the unit. If recording outdoors, use a windscreen over the recorder's microphones to reduce wind noise. Ask everyone in the room to turn off their cell phones, as even the 'silent' vibration mode can often be picked up by the recorder's sensitive microphones. Once the recording has started, state your name, date and location, then ask everyone to state their name one after the other, in roll call fashion. The reason is to be better able to identify a voice of someone in the room if, by chance, you believe you may have captured an EVP. Do not attempt to rely on your memory of the recording session! Explain to any entity who may be present what you are trying to do in as basic terms as possible, remembering that the entity may have been alive well-before the advent of recording technology. Ask them to please answer your questions (remember your manners!) and that you will give them time (usually 15 seconds or so) to respond between questions. It is always best if only one person in the room is designated to ask the questions to avoid confusion. Ask simple questions, consisting of only a few words. When ending the session, thank the spirit for his/her cooperation. Try not to review the recording on location unless absolutely necessary, as quiet and perspective away from the session are important in evidence review. Always review the evidence with a good set of headphones or earphones, not the recorder's internal speaker.
As I stated in the beginning, the 'voices' are either there, or they're not. If you still feel that you need to use software such as Audacity on a recording after following my advice, guess what? They're not.