The equipment used for recordings is basic and easily obtainable on any high street. Up to three laptops are used to analyse each recording, all are standard unmodified machines with factory fitted sound cards. All laptops run Audacity 1.3 beta (Unicode), a free open source sound editing platform that is available online. Four digital recorders are used; two Olympus VN2100, a Sony ICD-B600 and an Olympus LS10 (since the end of the study an Optimus CTR-109 Cassette Recorder, using high bias cassettes was introduced). Audio devices are not fitted with external microphones for recordings. After the sitting, data is immediately transferred from all devices to Audacity in real time. Direct file transfers were only possible from the Olympus LS10; these had fewer voices verses the same recording transferred via a cable.
Not all recordings were technically successful in the study. On entering the séance room, digital recorders were fitted with new batteries and tested to be working. In three sittings recorders were found to be turned off after opening; all worked perfectly when tested after the session. It was interesting to note that the recorders that failed were those that were less likely to capture EVP. At no time during the study or since, has either of the Olympus VN2100s been turned off. Early in the study period, an infrared Sony video camera was trialled and failed in three sittings; the first time the camera was turned off after the sitting opened, two following attempts were unsuccessful because the data was corrupted and irretrievable. Again, in common with the digital recorders, the video camera was testing and worked with no faults after the sitting closed.
The time taken for reviewing a sitting is lengthy. A two hour recording after transferring to the computer, may take from 20 - 30 hours to screen for EVP. Auditory acuity increases with practice but periods of intensive concentration can not be maintained for more than two hours without a break.
Once clipped the EVP are played as soon as possible to those who attended the sitting. It is important that reviewers have a fresh memory of the discussions held in the séance. Depending on our understanding, EVP clips are then graded into three categories; A – clear and easily understood by most listeners, B – understandable with repeated playing or earphones, C – difficult to understand speech or a noise not heard in the séance room at the time of recording. The entire recording and EVP graded clips are archived by sitting.
The ability to obtain EVP on four digital audio recorders and on three laptops, illustrates the phenomenon is not an inherent or idiosyncratic anomaly to one device. When used together both Olympus VN2100s were capable of picking up the same voice, at varying levels. Only two voice clips were captured on the Olympus LS10 at the same time as a VN2100, although audible they were Grade C clips and not easily understood.
White noise of 5 MHz was used only in a small minority of recordings in 2009 as a carrier wave. These sittings were outside of the specified study period and its use was not seen to increase capture of the voices, it was therefore discontinued.
Initial tests using electrostatic shielding bags to exclude radio wave transmission and electrostatic interference from recordings are encouraging, voices are still present but more sittings are needed before reporting the results.