Electronic voice phenomena (EVP) is commonly used as evidence of ghosts trying to communicate audibly. You can find EVP clips on the internet or listen to them on TV shows like Ghost Hunters. I've listened to various clips of alleged EVPs, and some of them are rather intriguing. Sometimes they seem to say a person's name or respond to a question out loud.
But they aren't very clear. They usually just sound like blips of static to me. Once the ghost hunters suggest what they think the static says, I do think to myself, "Oh yeah, it does kind of sound like that I guess." But is it really saying that? Or is it just the power of suggestion? Are we just trying to hear what were told to hear? I don't know, maybe I'm just not good at interpreting EVPs.
But lets go ahead and assume for a moment that EVPs are communications from the spirit world. Why are they so brief? Why don't the ghosts ever seem to give many details? Why don't they say more? Is it difficult for them to communicate via sound waves? Do they have to muster up a lot of energy just to make a sound that an electronic device will pick up that will sound like a spoken language understandable to the listener?
Someone might argue that the ghost hunters can't hear the ghost say anything at the time, so they aren't able to carry on a conversation with them. But if that were the case, why not just explain to the ghost that they can't hear them now but that they are going to leave a recording device running and ask the ghost to give them a full dissertation on who they are, what the 'other side' is like, and what they do all day and that they will check back on the recording device later for any messages.
What if the ghosts have another reason for not saying that much though? What if they are intentionally vague because they don't think we can fully comprehend their answers? Sometimes ghost hunters sound like they are talking to a scared toddler when they talk to a ghost. Maybe they should consider the possibility that the ghosts know more about being ghosts than they do. Maybe they should consider that the ghosts are not confused and are fully aware of what is going on. Maybe the ghosts think we wouldn't be able to understand what its like on the 'other side' yet. Maybe it's like how a parent waits until a child reaches a certain age before they tell them about the birds and the bees. Maybe the ghosts think we're just to 'young' to understand.
But actually, I think it's probably more likely that the ghosts find it difficult to communicate via electronic recording devices. People have communicated (or at least appeared to communicate) with spirits via Ouija boards for years (Ouija boards are not recommended though!). Psychic mediums have claimed to communicate with spirits in another way. Ghost hunters have apparently carried on conversations with spirits via K2 meters (either that or they've gotten really really lucky with getting the device to light up right after asking questions out loud). So it's not necessarily that ghosts are always short on words, they just don't seem to be to fond of saying a lot on electronic recording devices.
Of course, I can't dismiss the possibility that the static is just static from a random radio wave passing by. But there's still plenty of other types of evidence to suggest that ghosts do exist. I'd still believe in ghosts even if EVPs were just static.