MP3 vs. WAV Format Recordings….

Ever considered what kind of recorder you are using? Do you know what audio artifacts are? Everyone whose performing EVP sessions should understand what an artifact is and how it could give rise to false positives in your original recording files and if you upload MP3 files to the net. Found this interesting little video on youtube… shows exactly how distortion and artifacts can effect your recordings.

Dynamic vs Electret Microphones

The following unique recorded event was captured on 2/20/2013, during an experimental audio recording session. This session was supposed to be a comparative experiment session deploying a dynamic microphone which is jacked in into a Sony IC digital audio recorder using and ART pre-amp; then compared with another Sony digital audio recorder, that is using only its stock electret condenser microphone. The set up was on a table in a small room within a building where all occupants were cleared out, and all lighting sources along with electrical appliances in the room turned off. The synthetic voice was played by a battery operated  MP3 player and speaker system. Before we get to those recordings, lets cover the basics of what was used here.

THE TYPES OF MICROPHONES USED.

(Text Source Wikipedia) Dynamic microphones work via electromagnetic induction. They are robust, relatively inexpensive and resistant to moisture. This, coupled with their potentially high gain before feedback, makes them ideal for on-stage use. Moving-coil microphones use the same dynamic principle as in a loudspeaker, only reversed. A small movable induction coil, positioned in the magnetic field of a permanent magnet, is attached to the diaphragm. When sound enters through the windscreen of the microphone, the sound wave moves the diaphragm. When the diaphragm vibrates, the coil moves in the magnetic field, producing a varying current in the coil through electromagnetic induction. A single dynamic membrane does not respond linearly to all audio frequencies.

(Source Wikipedia) An electret microphone is a type of condenser microphone, which eliminates the need for a polarizing power supply by using a permanently charged material. An electret is a stable dielectric material with a permanently embedded static electric charge (which, due to the high resistance and chemical stability of the material, will not decay for hundreds of years). The name comes from electrostatic and magnet; drawing analogy to the formation of a magnet by alignment of magnetic domains in a piece of iron. Electrets are commonly made by first melting a suitable dielectric material such as a plastic or wax that contains polar molecules, and then allowing it to re-solidify in a powerful electrostatic field. The polar molecules of the dielectric align themselves to the direction of the electrostatic field, producing a permanent electrostatic “bias”. Modern electret microphones use PTFE plastic, either in film or solute form, to form the electret. 

ANOMALOUS CAPTURE.

While the intent of this recording session was purely to observe differences in recording qualities… something unusual was caught. If you look closely at the top track in the waveform and spectrogram, there is a flutter of activity after the question is asked. Which to my ears almost sounds like tiny foot steps scampering across a the table where this experiment was occurring. However as you can observe in the waveform and spectrogram imagery of the bottom track; the event occurs only on the dynamic microphone.

If this had been caught on both microphones, I’d be inclined to say it might have actually been a mouse running across the table. Since the recordings are both of comparable audibility without software amplification; I am inclined to say this an event of either an EMF or RF emergence; whether or not this is a natural or paranormal event, is not absolutely provable either way at this point. Could it possibly have come from the mp3 player and speaker used several feet away…  maybe… but in the hour of mp3 player/speaker operation during this session, this is the only location on the files where this occurs… Nor have I seen this kind of event on my other recording sessions I’ve done using similar set ups… So I’ll leave it as anomalous in my books without other evidence.

Is this one experiment conclusive of anything? No… it is interesting, but as with any experiment, it needs to be replicated numerous times, and by people other than myself. So give it a try on your own, and see what you get! 

It is however something of interest for demonstrating that Dynamic Microphones do capture things that electret condenser microphones do not.

Additional experiments for trying to discern EMF Events from acoustic events would be to replace the condenser microphone with an EMF-Probe such as a coil antenna, a commercial probe like a magcheck-95, or even a simple RadioShack inductive phone recording pick up. These items would not record the waveform of a sound event at all, but the waveform pick up of EMF. Controlled experiments would include not using a mp3 player with speaker to play an audio track; but use a broadcast method that pumps out the track questions in emf vs. sound waves. Place this item near the two microphone set up and see which one captures the emf modulations.

When you listen to the files below you will notice that the electret microphone recording has less background noise giving an over all more quiet texture… This may be due to the inherent noise cancelling properties and emf/rf shielding that are built into modern electret condenser microphones/recorders. The Dynamic microphone is subject to pick up the noise floor threshold which is the  emf given off by computers, lighting systems, appliances, remnants of the big bang… etc… etc…

(Text Source Wikipedia) In signal theory, the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system, where noise is defined as any signal other than the one being monitored. In radio communication and electronics, this may include thermal noise, blackbody, cosmic noise as well as atmospheric noise from distant thunderstorms and similar and any other unwanted man-made signals, sometimes referred to as incidental noise.

IMAGES AND SOUND FILES

Images can be enlarged by clicking upon them. It is also suggested that you listen to the following files with good quality speakers or set earphones. Do not use noise cancelling earhpones or speakers… they will block out sounds that may be integral in hearing whats on these files.

Comparative Waveform Views; (Top Track) Dynamic Microphone (Bottom Track) Electret Condenser Microphone)

Comparative Spectrogram Views; (Top Track) Dynamic Microphone (Bottom Track) Electret Condenser Microphone)

HERE IS HOW THE TOP TRACK SOUNDS – DYNAMIC MICROPHONE

HERE IS HOW THE BOTTOM TRACK SOUNDS – ELECTRET CONDENSER MICROPHONE

TECH TIME – Creation of a Cheap EMF Sensor

MNPARA-SCI Commentary: Was browsing the YouTube vids again… Came across this interesting clip on using a 10.00 radio shack inductive telephone pick up, and a simple audio recorder, to create an audible proximity EMF Sensor. In the video application below you can listen to the varying sounds created by EMF sources in your environment. I plan on using this in principle, by replacing one of my microphones in my divergent microphone recording system with an inductive mic. That way I can visually (in general) correlate – documented proximity EMF spikes, at the exact time an EVP/AVP occurs on my recording tracks. Helping to further establish the EMF and EVP-AVP connection. ( This is not entirely a new idea…) research performed by David Roundtree already asserts this and has performed tests using much more expensive and higher grade equipment that establish this. As I work with this idea, I will be posting more about it.

Disclaimer of Fair Practices-Usage: Materials contained here-in are intended to be used as an educational source only. This is a non-commercial usage of this material. The posting party receives no monetary profit or compensation for this material. All credit for original work is given to the creator of this material.

Credit to Source: VIPER PARANORMAL – SCREAMFREAK 79

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The RVPR Mark II – One of the Best EVP Collection Set Ups

I chat with this guy a bit over on facebook! Paul explains one of the best divergent microphone builds for capturing EVP’s that I’ve ever seen! Very informational and a must for any EVP investigator!

Check it out the rest of this guys vids at his channel!

DIVERGENT MICROPHONE SYSTEMS FOR EVP CAPTURE AND SCREENING

DIVERGENT MICROPHONE SYSTEMS FOR EVP CAPTURE AND SCREENING. Based on Observations of MNPARA-SCI

Over the last 1/2 year now I’ve been deploying a specialized recording technique for capturing electronic voice phenomena and acoustic voice phenomena. This specialized technique is based on the research of David Roundtree, and others, with similar theories that EVP (electronic voice phenomena) and AVP (acoustic-audible voice phenomena) are two different and distinct events. (check the Raudive Phenomena page on this site for more on this theory.)

This technique entails using two divergent types of microphones, used in such a fashion, that they create a two channel audio track recording. (Which is created through either a computer recording interface or recorder/pre-amp set-up.) The first microphone is a dynamic coil microphone, which is the primary recording tract. The second microphone creates a comparative control track and is recorded with a condenser, or electret condenser, microphone.

The premise behind this specialized technique is that a dynamic microphone can capture emergent, electromagnetic field based electronic voice phenomena, within the magnetic coil component of that type of microphone. Whereas the condenser or electret condenser microphone does not have this capability and is virtually deaf to EMF based EVP’s. The simple technique afterwards is to examine the two-track recordings and look for recorded events that occur on the primary dynamic microphone track, but do not appear on the secondary-comparative condenser, or electret condenser, recorded track.  To learn more on this I recommend checking the Raudive Phenomena page on this site… or pick up a copy of David Round Tree’s book Paranormal Technology.

Now that the premise and practice for this technique is established… I have found that there is a major issue that needs to be covered before application. I have seen various media on how to put together these kind of set ups, and I am impressed by most of them. But, I have not seen information on a specific technical aspect which I feel is pretty important. That being the importance of selecting the appropriate acoustic recording polar pattern, for the condenser based control microphone, and I think this is huge! Especially if you really want to nail down this technique, and to really identify EMF based EVP’s from other sound based events and phenomena.

Lets start off with this type of EVP recording set-up being used by many folks. (Mine included… See left image). Typically these set-ups use a two divergent microphone system. The first, and primary recording microphone, is a dynamic microphone. The acoustic polar pattern of the mic is not necessarily important, unless you want to maximize your chances of capturing AVP’s (acoustic voice phenomena), in which case I would recommend a omnidirectional microphone. The second, or control-comparison tract microphone, is a condenser or electret condenser microphone, whose acoustic polar pattern is extremely important. Each one of these microphones are then routed to a recording device, that compiles these two different recordings into a single two-track, observable recording that can be easily displayed and reviewed. (See Below)

The principle technique for screening of EMF-EVP with this set-up is really simple. EMF-EVP will appear on the dynamic microphone recorded tract, while they will not appear on the condenser – electret condenser recorded control track. Sounds simple doesn’t it. When you have the right equipment it is… But before everyone goes out and buys dynamic and condenser microphones, recorders, and pre-amps; we need to explore this just a bit farther.

The condenser, or electret condenser,  microphone being used as a comparison and control, must be able to capture audible sound in the same acoustic polar pattern as the dynamic microphone’s EMF polar pattern capture ability.  Dynamic microphones, no matter what the acoustic polar pattern is, will be able to capture EMF-EVP coming in from any direction, in a 360 degree (omnidirectional) pattern from the microphone’s dynamic coil system.  That requires the control track condenser microphone, must be able to capture sound that comes in at a 360 degree angle as well. That way you can make an accurate comparison between the two tracks. This requires that an omnidirectional acoustic polar pattern, condenser or electret microphone, is the only acceptable microphone. (… or you will have to use of multiple condenser microphones to assure 360 degree sound coverage… increasing your recordings to at least a 4 track recording system requiring more equipment and costs more.)

Let me say that again… I believe that if you do not use an omnidirectional condenser microphone; or use multiple condenser microphones to allow for 360 degree coverage, you will not have an accurate control tract to compare to your primary dynamic microphone recording track, and that can make your conclusions invalid. (Example Reasoning Below)

Look at the patterns chart, and lets assume you capture what you think is a possible EMF-EVP. You have used a two-track divergent microphone system as refered to above. Remember with all dynamic microphones, your coil’s EMF polar pattern will always be omnidirectional, meaning the capture could be coming in from any direction within 360 degrees of the coil.

Lets now say your control condenser microphone, or electret condenser microphone, is a cardioid acoustic polar pattern. You are only collecting sounds coming in within a range of 131 degrees from the microphone. This lower coverage angle means that you are only collecting roughly 33% of incoming sounds… What does that tell you? You are missing 66% of the sounds. That 229 degrees of incoming directional sounds have been missed and your control-condenser recording track is now incomplete and flawed. When you use that flawed control track to compare with the dynamic microphones track You missed 66% of the sound data necessary for 100% confidence in your screening against the 360 degree, omnidirectional, EMF capture ability of that dynamic microphone.

Here is a great general information table on the acoustic polar paterns of microphones.

So when you start putting together your divergent microphone set-up, for capturing and screening for EMF based EVP’s… Think omnidirectional for all of your microphones used. To keep it simple, use only omnidirectional acoustic polar pattern, condenser or electret condenser,  microphones to generate your control-comparison track for your primary dynamic microphone track. This will allow for near 100% comparative certainty, in relative comparison, to the omnidirectional EMF polar pattern capture ability of the  dynamic microphone you will be using.

Happy Hunting!

MNPARA-SCI 2013.