Forensic Sound Analyses of Cellular Telephone Recordings

Recordings involving cellular telephones or personal digital assistants (“PDAs”) are increasingly the source evidence in audio forensic examinations, compared to recordings originating with other devices such as hand-held digital recorders. On modern PDA cellular telephones recordings can be made either directly to the telephone or transmitted as voice mail messages. The current investigation focuses on differences in the two types of recordings in terms of dynamic range and linearity of levels. Such information can be important for characterizing the distance of sound sources relative to the microphone and are important for understanding transformation of recorded speech and non-speech sounds.