Jan 4, 2005 Meeting with audio consultant in preparation for this study. Some of the questions posed to him are answered here.

Study info to follow. Q. If a person is talking at, say, a frequency of 500 hz... and he talks into a microphone and broadcasts over the radio... and I am sitting here tape recording what is coming over the radio.... is my recording of that voice going to be the frequency the at which radio station broadcasts? or will it be 500 hz because that was the the frequency of the announcer's voice? A. The recorded frequency will be the original 500 hz of the speakers voice. Actually ... his voice is combined with a "carrier frequency" generated by his transmitter. When your radio receives that signal ... it removes the "carrier frequency" ... and leaves just the original audio frequency of 500 hz. That is later amplified and in the case of a stereo or radio with an equalizer ... further modified  so that the actual audio tone heard from the speaker of the receiver may or may not be the EXACT 500 hz that was originally sent . since the wave shaping features of controls such as treble and bass . can modify the original tone to suit the listening pleasure of the listener. Long story short ... audio frequency INTO the microphone is the same as audio frequency OUT of the speaker on the receiver. Everything else done in between ... simply acts as a method of conveying that audio signal from the transmitter to the receiver. Q. You said: "When your radio receives that signal .... it removes the "carrier frequency" ........ and leaves just the original audio frequency of 500 Hz." Is the carrier frequency  the frequency of the radio station?? For example if  93.3 FM on the dial the carrier frequency....does that mean the frequency is 93 hertz??  A. Correct ...the carrier frequency is the one you hear advertised ... so 93.3 FM ... has a carrier of 93.3 mhz.  Carrier frequencies can vary from very low ...... to ultra high frequencies ... but they all perform the same task ... that being the ability to convey the audio information.  Q. "That is later amplified" So you mean the 500 hz voice is made louder, right? A.  Correct again ... the signal pulled from the air by your receiver .... is very weak after the carrier is removed ... and unable to power a typical speaker (though some small earphones will work ... but are only practical for the most basic of listening). This weak audio signal goes through an audio amplifier in the radio .... which multiplies the strength of the signal ... high enough to drive the speaker. The volume control on your radio .... actually controls how much this amplifier multiplies the original audio signal. Likewise ... any shaping sections such as treble / bass .... further control WHICH audio frequencies will get amplified the most. That is how an equalizer works .... by controlling the AMPLIFIER section .... and allowing the chosen frequencies to be amplified louder than those the listener does not desire. Again ... this is all a function of the audio amplifier ... but the ORIGINAL SIGNAL which is fed into the amplifier .... remains faithfully the same as the original signal sent by the transmitter.  Q. You said "the actual audio tone heard from the speaker of the receiver may or may not be the EXACT 500 hz" So about how far off may it be? like....100 Hz or just a couple of Hz A. The exact amount of change will vary based on the type of amplifier, and the types of wave shaping controls present. It is safe to say ... it can vary as little as a few HZ .... to as much as several hundred HZ. Keep in mind though ...that once a setting has been made (if available) ... to control the treble or bass of the signal .... that setting will remain constant until manually changed. So if the frequency was 500 hz .... and it is moved to 550 hz by the amplifier controls ..... it will remain at 550 hz.  Q. hmmm that is not what I wanted to hear. There is no way then, to prove that a recorded voice is not humans except by the frequency. Not to say that a ghost cant speak at a high frequency....but a human can be ruled out if the voice recorded is below a certain point. Although who's to say if a spirit voice is actually coming over the radio or not? People have used the radio as a source of white noise but I would like to be able to rule out a person coming over the waves between stations...know what I mean? Another question... Is it true that a human voice box can't make a sound less that 300 Hz?? That would help prove that a voice recorded isnot human. A. Not sure on that one ... sorry to say ... But almost sounds likely... Since once you get lower than that ... it's usually able to hear a pulsing tone rather than a pure note. So ... having said that .... I wouldn't say that it's impossible to produce a lower tone... but it would sound harsh and raspy to the ear.  ALL audio waves are a series of peaked pulses ... and the frequency or number of those pulses is shown as HZ. Get low enough in the HZ ... and you can start to hear the spaces between the pulse peaks. More like the ear isn't capable of filling in the blanks so to speak??   Q. If I was to use a radio tune between stations, Is there a frequency where it would be less likely to pick up a radio station? I was going to use a crystal radio I am building. I am wondering if all the answers you gave me are the same for this kind of radio. A. The principals are the same ... and I assumed a similar design when you mentioned the crystal radio. These radio's act more as a "detector circuit" .... Without much in the way of amplifiers for incoming radio signals... or audio output. For your application ... that is good. The problem is .... the crystal radio can't tell the difference between a radio station / appliance interference / etc. ... as it is a very wide band device. That is good for ghost listening .... but bad when it comes time to prove the voice or sound heard ... wasn't produced by some external factor. Without a clear input / output comparison ..... it's up to the listener to decide if what they heard was supernatural ... or easily explained by modern day American electrical interference? Again ... the audio approach .... does give an in / out comparison .... so that was my line of thinking. A crystal radio may be a good choice ... since it does NOT have much in the way of an amplifier that can change or shape the sounds heard. As for frequency ... it is all a gamble ... and most ANY radio frequency device such as a radio / garage door opener / cordless phone / etc ... is subject to noise interference from other similar devices, as well as electrical noises that can be caused by faulty appliances or even electrical utility poles with corroded connections. SOOOooo ..... to absolutely rule out ANY possibility of external sources causing a sound or tone on most ANY radio frequency appliance .... is pretty much impossible. You can greatly reduce the likelihood ... but never ... fully eliminate it. One thing I would suggest ... DO NOT ... attach any antenna to your crystal radio .... that should greatly minimize the chance of external RF interference ... though it may reduce sensitivity too. My approach has been to consider applying audio white noise into a recorder ... directly. Simultaneously record the white noise ... and the ambient room sounds. When you compare the two ..... any new noises on the white noise tape... can be verified against the ambient room tape ... as being newly introduced via the white noise carrier. Still working on the details... but that was my approach. It kept things in the audio spectrum ... where the ambient recording could act as a reference (along with the searchers own ears) ... as to what was said / done in the room.

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