Digital Data Transfer

Forensic Audio Frequently Asked Questions

Q: Can you make very soft voices audible?

A: Yes, if there is enough signal to work with. DDT has successfully recovered a mostly inaudible whisper from poor quality audio cassettes.

Q: Do you alter the original recording in any manner?

A: No. The original is played back on an appropriate device for transfer to the digital system.

Q: Can you recover anything from an erased tape?

A: In most cases, it is doubtful whether meaningful information can be recovered from an erased tape.
The chances of recovering anything useful is exceedingly small. We Offer to attempt recovery from any condition media.

Q: My tape is damaged. Can you repair it?

A: It depends on the nature and severity of the damage, as well as whether it was damaged during playback or recording. DDT has been very successful salvaging damaged tapes.

Q: I have a message on a digital voice messaging system that needs forensic examination.
What do I do?

A: DDT can retrieve the message directly from the voice messaging system.

NOTE: What happens if you try to record this yourself by holding a microphone to the telephone earpiece. This usually results in a very unsatisfactory recording with the voice being very faint or garbled, as well as the introduction of interfering background noise. Contact DDT for voice messaging retrieval. DDT uses a professional telephone interface and records directly to the digital system. The recording will then be sent to you on CD.

Q: My recording sounds like Chip & Dale. Can you make it sound normal again?

A: Yes.

Q: Do you have to work from an original recording, or is a copy suitable?

A: It is preferable to work from the original recording. It is doubtful whether a copy will be given the credibility you might like if it is to be used as evidence in a court of law. Also, a copy has a loss of fidelity, and thus detail. The original should be used for analysis and processing when possible.

Q: Do you return the completed project on cassette or CD?

A: Completed audio projects can be returned on standard analog cassette, digital tape or CD.

Q: Do you work only for attorneys and law enforcement?

A: No, anyone can obtain DDT services.

Q: Can you eliminate annoying background noise such as a TV, wind,rain, or traffic noise?

A: These sounds are called masking signals and selective elimination depends on how much of the masking signal is mixed at the same frequency as the desired signal. Masking signals can always be reduced, but the possibility of total elimination depends on many factors.

Q: Can you eliminate hum?

A: Yes.

Q: Can you tell if a tape has been altered?

A: In most cases, it is possible to detect whether a tape has been altered. Sudden changes in background ambiance, frequency spectrum and amplitude are common signs that an alteration has occurred. There are other techniques which can also be used to detect alterations to an original recording.

Q: Will you supply a report?

A: Yes, if requested. The report may be a brief procedural overview, or an extensive detailed report with high quality graphics for court presentation. Report writing is billed at the standard DDT hourly rate.

Q: Can you estimate cost?

A: DDT bills by the hour, with a minimum charge of $200. The real difficulty of estimating cost for a particular job is estimating the amount of time required to perform the tasks involved. For most forensic audio jobs, the time required is a function of the length of the recording, the quality of the recording, the nature of the task(s) to be performed, and the urgency with which results are required. See our RATE CARD

DDT is committed to helping clients find cost-effective solutions to their problems, and may be able to help minimize the cost of a particular job by working with the client to determine precisely what is needed. For example, it may be the case that on a given tape, intelligibility is only an issue for a few words or phrases. In such cases, DDT will help the client determine which of those words and phrases need intelligibility enhancement, and will focus only on those areas of the tape. This can result in significant savings.

Naturally, the more information DDT has about the nature of the job, the better it can estimate the cost. A description of the problem, for example, in a telephone call provides only the broadest parameters and rarely provides sufficient information for a reliable estimate of the time required to perform the task. Even after listening to the tape, it is difficult to make a reliable cost estimate because of the extreme complexity of the procedures involved in forensic audio.

Q: Will you evaluate my recording before I decide to continue with the work?

A: Yes. There is a small charge, paid in advance, and includes return shipping if you decide not to continue. If you decide to continue, the charge is considered a retainer (or partial retainer) and is applied toward the total charge. Call for details.

Q: How do I pay you?

A: A retainer is required for all forensic work. The amount will vary, depending on the type of investigation and the amount of time it is expected to tie up DDT resources. The minimum retainer is $200 and may increase to several thousand. Completed work is returned FedEX COD. Prior arrangements must be made for other billing and payment requirements.

Q: Will you make a transcript?

A: DDT will allow anyone you designate to come into the studio and make a transcript. DDT's playback facility is far beyond the quality found in most offices or homes, thus this is a very good way to obtain an accurate dialogue decoding and transcription. Digital playback of an enhanced recording has more detail (clarity) than an analog copy. Also, special decoding playback techniques can be used such as momentary time expansion, section looping, or setting the eq of a section to the specific hearing ability of the decoder. DDT does not provide a transcription service, but can recommend local professionals who can make such a transcription.



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