Unfortunately, nearly all such recordings are filled with extraneous noise, making it difficult to understand and accurately transcribe the conversations. Noises from air conditioners or fans, reverberations or room echoes, the humming of the induction device used to make telephone recordings all these and other noises combine to perplex listeners. But by using new sound tools available to forensic audio laboratories today, unwanted noises can be removed or reduced and sound quality of recordings can be enhanced. Computers to the Rescue Noises or masking sounds must first be analyzed to determine their frequency range and complexity. By using computers, frequency spectrum analyzers and other waveform measuring instruments, the expert can properly select the correct method for removing the noise.
Enhancement generally takes place after the noise removal process.
Digital audio computers, filters and equalizers are used to spectrum shape or otherwise cause the enhanced rerecording to sound better or become more intelligible. Too often jurors are handed partial or misinterpreted transcripts. Often they are nor aided in the listening process, having to correlate what they think they hear with the transcribed version they hold in their hands. Accurate evaluation of the content is, at times, virtually impossible. The expert employed to create an enhanced version can attest to its content and the process by which the re-recording was made.