Forensic Audio (Audio Forensics) Frequently Asked Questions

Q: Can I upload digital files to you?

A: Yes. CAE provides both upload and download of digital files with database logging for legal purposes if needed. Once you have retained CAE a secure password protected upload/download will be assigned to you if requested. This is assigned on a need-to-have basis.

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Q: Do you provide expert witness testimony?

A: Yes. CAE is experienced with giving testimony in both federal and and state court systems.

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Q: Do you work with audio from a video?

A: Yes. CAE can enhance the audio on your video and sync it back to the video.

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Q: Can you do video enhancement?

A: Yes, but with some qualification. CAE is not a video facility but can do some very good enhancement due to the professional equipment used for working with the audio from a video. CAE does not do video authenticity analysis.

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Q: Can you make very soft voices audible?

A: Yes, if there is enough signal to work with. CAE has successfully recovered a mostly inaudible whisper from a telephone line transmission noise floor.

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 erase head of a recorder precedes the record head and is automatically activated when record mode circuits are engaged. When recording, the erase head places an alignment tone on the tape just prior to the record head recording. This alignment is that of the magnetic particles of the tape, which is done by placing a high frequency of between 50 khz and 100 khz on the tape to ensure proper patterns conducive to recording, thus "erasing" previous material. However, what it does not do is penetrate deeply (saturate) into the physical tape and sometimes it is possible to recover some low frequency signal. This signal may or may not be intelligible. That will depend on the amplitude and quality of the original signal, and the quality of the physical tape. Also, head alignment differences between players may yield some results, and it is always possible the erase head of the original recording equipment has malfunctioned and some previous signal remains. However, the chances of recovering anything useful is exceedingly small.

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.

A: No, anyone can obtain CAE services.

Q: Can you eliminate annoying background noise such as a TV, dishes clattering 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. A masking signal can be as much as four times the amplitude of the desired signal before desired dialogue/signal information is completely lost. Note that low frequencies can completely mask higher frequencies, but rarely will higher frequencies completely mask those lower. In the latter case, the problem is more one of distraction than of complete obliteration.

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. For more information and examples click here.

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 CAE hourly rate.

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Q: Can you estimate cost?

A: CAE bills by the hour, with a minimum charge of $300. 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.

CAE 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, CAE 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 CAE 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, but not for free. If CAE honored ever evaluation request for free it would cost CAE thousands of dollars a year in lost income. You must pay the minimum retainer of $300. This will get you a two hour evaluation, and includes return shipping if you decide not to continue. If you decide to continue, the retainer is applied toward the total charge. Call for details.

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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 CAE resources. The minimum retainer is $300 and may increase to several thousand. Completed work is returned FedEX COD. Credit cards are accepted on-line but not by mail or telephone - click here for more information if you want to use the credit card option. International clients must prepay before shipping. For additional policy information click here.

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Q: Will you make a transcript?

A: Yes. CAE'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. Please be aware that this adds significant cost to your project

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