Here you will learn about EVPs which stands for  "Electronic voice phenomena"  

EVPs can be captured through any standard audio recorder. some have different features such as Tape or digital, fast transfer or live transfer, also some recorders are capable of allowing you to listen to what the recorder is picking up while it is recording. (be aware some recorders with moving parts can pick up the noises of the internal gears)  Even some cell phones can record audio during a EVP session. there are a lot of different types of equipment now days to use for this purpose but the most common is a dictation recorder. Determining what one is the best for you will be the first step.  there are aspects in the decision such as cost, how often are you going to use this also what other things you can use these for.  We have found these to be a valuable source in many aspects in and out side the paranormal field.

Understanding Audio/sound

EVP stands for Electronic Voice Phenomena. this is audio that is capture on a voice recorder but may not have been heard at the time it was captured. the belief is either the investigator was involved with all the other surrounding distractions or that the audio was at a level that is below human hearing. the recorder can pick up these levels and automatically raises them to a level that can be heard.

Human reactions to infra sound

20 Hz is considered the normal low frequency limit of human hearing. When pure sine waves are reproduced under ideal conditions and at very high volume, a human listener will be able to identify tones as low as 12 Hz. Below 10 Hz it is possible to perceive the single cycles of the sound, along with a sensation of pressure at the eardrums.

The dynamic range of the auditory system decreases with decreasing frequency. This compression can be seen in the equal-loudness-level contours, and it implies that a slight increase in level can change the perceived loudness from barely audible to loud. Combined with the natural spread in thresholds within a population, it may have the effect that a very low frequency sound which is inaudible to some people may be loud to others.

Infra sound has been known to cause feelings of awe or fear in humans.  

Since it is not consciously perceived, it can make people feel vaguely that  supernatural events are taking place.

Some films soundtracks make use of infra sound to produce unease or disorientation in the audience. Irreversible is one such movie.

The infra sound and low-frequency noise produced by some wind turbines is believed to cause certain breathing and digestive problems in humans and other animals in close proximity to the turbines.

There are 3 different classifications in which they can fall under.

Class A: is an EVP that is heard clearly. In which everyone who hears the same thing.

Class B: Can be heard but people hear different words or sentences.

Class C: is heard by some and not others and may not even be understood what if anything was captured.                                           

While conducting a EVP session there are a lot of different styles that are used. Every where from respectful to provoking.  The style you choose may determine what type of results you get. Another thing to be aware of is knowing what you are going to ask ahead of time. This may change during the session but it's a good idea to have a few questions in mind before you start.   We recommend before you start a session to sit and listen to your surroundings for a few minutes and try to identify any noises that you hear.  ex: Clocks,cars,heaters,people out side or in other rooms.  also pay attention to where heater vents are because they can carry noise through them from the other side of the Location. When activating your recorder remember to state the time,date and members that are with you. One more thing to remember, No whispering. when reviewing a session a whisper can mis-lead you into thinking it was a response.  

Once you start your evp session ask a question and wait a few moments to allow time for a possible answer.   then ask another question.  During the session it is also a good idea for more then just one to ask questions because if there is something there it may respond to them instead of you. (It's happened) . Remember that if there are noises during the session point them out so the one reviewing it later knows what the noise was. EX: That was Jim closing the door or that was Mary sitting down.

Some of the things my team does is announce who we are and explain "we are here to try and communicate with you. We have this device that may help us hear you."   at the end of the session we always thank them for spending time with us.

Now that the session is finished it's time to review.  Depending on your recorder type you can do 1 of 2 things. First you can listen to your session out of the speaker on your recorder or you can transfer it to your computer and review it that way. It is a good idea to use head phones to block out any distractions around you and it helps hear the noises you are looking for.

there are a few software programs that are out there that are nice to use. one of them is called wave pad.

there is a free version without any expiration dates and very useful.           to Download click here.

 Some of the Features include.

Sound editing functions include cut, copy, paste, delete, insert, silence, auto trim and more.

Audio effects include, amplify, normalize, equalizer, envelope, re verb, echo, reverse, sample rate conversion and more.

Supports a number of audio and music file formats including mp3, wav (multiple codecs) vox, gsm, real audio, au, aif, flac, ogg and many more.

Tools include spectral analysis (FFT) and speech synthesis (text-to-speech).

Audio restoration features including noise reduction and click pop removal.

Easy to use interface will get you started editing in just minutes.

During the reviewing process you need to avoid any out side distractions other wise there might be a Response that you may not hear, also try to debunk the noises first. think of the situation you was in during that response. if there is no logical reason that can be thought of then clip a minute or so before to a minute or so after so it is easier to hear what was asked and what was done after.  (Just clipping the noise doesn't work out that well.)  After everything has been gone through have the other members listen to it as well and see if maybe they can explain it. If not then you may have a EVP. 

Another thing you may find out is even though you can hear a evp on your speaker system other systems equalizers may differ and not be so noticeable.