I got started with the paranormal because of a podcast I produce. When I saw an announcement of a public investigation, I decided to go, and bring one of the audio field recorders I use to record the podcast. I had seen people use them on investigations in programs on television, and I figured I could do the same. Ever since then, I have been hooked.
The primary challenge of EVP audio inspection is not capturing sound, but isolating meaning over the environmental noise. Raw EVP recordings are rarely pristine; they are recorded in environments including acoustic reflections, natural sounds, and atmospheric interference. However, when these recordings are analyzed visually using an audio spectrograph, vocalizations are revealed by their distinct visual signature characterized by harmonic banding and specific frequency modulations that stand out from random background noise.
Overcoming the desire for flawless recording requires a shift in thinking. If you are participating in an investigation open to the public, you have no control over the environment. Expect people to laugh, talk, whisper, shuffle their feet, and generally contaminate the audio.
To conduct a thorough review of audio data, you must use your eyes as well as your ears. I frequently watch paranormal entertainment shows where investigators spend hours reviewing audio in real-time, when this is totally unnecessary with the proper software. Sitting and listening to hours of raw data sequentially is an inefficient approach when desktop analysis software can process audio files visually. Visual spectrograms allow an investigator to scan a multi-hour recording in minutes, isolating anomalous audio spikes and distinct frequency bands visually without ever pressing play.
Take a look at this image. It is a spectrogram of the words "now is the time for all good men". It represents time, frequency, and amplitude all on one graph. A standard spectrogram plots data across three dimensions simultaneously.
- Horizontal Axis (X-axis): Represents time moving from left to right.
- Vertical Axis (Y-axis): Represents frequency (pitch), with low frequencies at the bottom and high frequencies at the top.
- Color / Brightness: Represents amplitude (loudness or volume). Warmer, brighter colors like red, yellow, or white indicate loud sounds, while cooler colors like blue or black indicate low energy or silence.
Notice that words are very distinctive with multiple bands resembling a seismograph. Speech is actually made at a number of frequencies and harmonics. It doesn't take long to learn how to recognize it in the spectrogram. You will also learn how footsteps and knocks "look". Just scrolling the timeline, you will find anomalies that are different from the background room tone. At first, you may stop at a sound, select it and listen to it, then decide that is, say, a bird chirping. After that, you will know a bird chirping when you see it and know not to stop and listen to it.
Scrolling the timeline of the waveform visually is much faster than listening to every second of audio. There are effects you can apply to the audio to reduce background noise. These are problematic. The EVPs are often very weak, and if you mask the background sounds, you could reduce them until they are unusable.
In rooms with no soft surfaces you will begin to recognize echoes. You own voice reflects off of surfaces and bounces back to you with the same pattern, but a lower volume. One way of knowing what is a person speaking and what is an EVP is in these rooms voices echo and EVPs do not. Remember this when you are looking for evidence.
Another thing that annoys me when watching paranormal investigations on television is people who hold a digital recorder with their hand. All it takes is a slight pressure of the fingers to record a spooky-sounding growl in the recording. This can happen even when they are not aware of doing it.
I always attach a portable shock mount to my recorders, then a mini-tripod to the shock mount. This isolates hand noises almost completely. That is exactly what a shock mount is made to do. You can still collapse the mini-tripod and use it as a handle when carrying the audio field recorder around.
You see some investigators setting their recorder down on a table to avoid handling noises. This is also a problem. It turns the entire surface into the equivalent of a drum, amplifying echoes and hum. It also flattens the sounds recorded, reducing the nuances of the recording. Putting the recorder on a tripod will fix this, even if you don't use a shock mount.
I live in Kansas, which translates to "people of the south wind," and it aptly describes the state. With all the flat plains, there is nothing to stop the wind. When I record audio outdoors, I always use a furry wind muff on the microphones. Some people call them dead cats. The dead cat is a marvelous invention. When air moves across the fur, that fur waves back and forth, dissipating the energy. The harsh scraping sound of wind hitting the microphone grille is almost completely eliminated. These wind muffs only cost a few dollars and will save your recordings. It is better to have one and not need it than the other way around. I leave them permanently on my microphones, even when recording indoors.
If you can afford one, buy a 32-bit float digital recorder. The dynamic range of these recorders is amazing, but better than that is the audio never clips. Clipping is when a sound is so loud it maxes out.
A lot of digital recorders make you adjust the audio recording level. When you do this, you want the recording to be loud enough to be heard when played back, but not so loud that it constantly maxes out the volume. It is difficult to find the right balance when you are trying to record tiny whispers all the way up to people shouting in the room.
Some digital recorders will automatically adjust the levels for you while they are recording. This is bad. If there are a variety of sounds, the louder ones will cause the recorder to lower the level, and then softer sounds fade into the background noise. This most often happens when you are holding the recorder and you ask a question. Because you are so close to the microphone, your voice is quite loud, so the recorder cranks the level down. A whispered response is not going to be picked up following that. Do not use automatic leveling to investigate the paranormal.
A 32-bit recorder does not have this problem. They don't have a knob to even set a level. If microphones were possible to do it, a 32-bit recorder could save the sound of a gnat landing on a flea, to a rocket launch, both in the same file. For those who are not professional sound engineers, a 32-bit recorder is ideal. Consumer-targeted 32-bit float recorders can be purchased for as low as $100.
Record at the highest lossless sample rate your field recorder can generate. I record WAV files at 96 kilohertz in stereo. Some recorders will allow you to save the data in an MP3 file to save space. Don't do that. The compression will introduce artifacts into the data. It is especially bad if you then edit the audio and then save it as an MP3 file again. High-capacity, fast SD cards are inexpensive and keep getting cheaper. I regularly record 4 to 8 hours of audio and have never even come close to filling up an SD card. The WAV file standard doesn't allow files any larger than 4 gigabytes, so when it exceeds that size, the recorder will open a new file automatically. A 96 kHz recording in 32-bit float stereo will hit that limit at 3 hours and 15 minutes. My recordings longer than that are in multiple files.
Speaking of recording time, I recommend turning on the field recorder and leaving it recording. Starting and stopping your recording will eventually cause you to forget to turn the recording back on, which results in lost data. In fact, most recorders have a switch that will disable the recording button so you can't accidentally turn it off. Use it. Remember that you can review the audio quickly on your computer and remove the boring parts while you do that.
My field recorders need batteries and I always replace them right before an investigation. I always bring extra batteries, but have never needed them for the field recorders. If yours is rechargeable, don't forget to do that. I have a power hub that will let me charge up to 20 devices at the same time. That is enough to charge equipment for a whole team of investigators.
Good quality audio field recorders will allow you to plug in external microphones. There are dynamic microphones and condenser microphones. Be sure to use the ones that work with your recorder. Consumer-level field recorders almost always have built-in microphones that are more than adequate for investigating, and you should use them just to reduce the possibility of equipment problems.
Even if you don't believe in EVPs, using a field recorder has its advantages. If you are recording video on a camcorder or a cell phone, the audio is going to be bad. Go ahead and record audio on your camera, but don't depend on it for documentation. The audio on a field recorder will be much better.
The better video editor programs will allow you to import additional audio and automatically align it with the video. If your video editor program doesn't do that, you can manually align them with a loud noise. A clapboard is traditionally used to do this. It's that board that is hinged on one side at the top and somebody slaps it down to make a noise.
Good clapboards are expensive. I use an animal training clicker. It fits in my pocket and makes a very sharp sound that is easy to locate in the waveforms of both the audio and video files, especially if you click it three times in a row.
Reviewing your data shouldn't mean sitting and listening to hours of raw, boring audio. By using a desktop spectrogram, you can use your eyes to scan a multi-hour recording in minutes, letting you spot anomalous audio spikes and footsteps visually without ever pressing play. To get the cleanest data possible, skip the automatic leveling and MP3 compression, and invest in a budget-friendly 32-bit float recorder so your audio never clips. Most importantly, focus on your physical setup. Mount your recorder on a shock mount and tripod to eliminate handling noises, leave a furry dead cat on your microphones at all times to block out wind energy, and just let the recorder run continuously at a high-quality 96 kHz WAV standard. Whether you are looking for EVPs or just trying to get better documentation to align with your video, these simple adjustments will protect your audio and save you a massive amount of time.
