A Digital Recording Guide
by Paul Ginsberg

We are truly in a digital age. Every jogger has an iPod. Every tourist has a digital camera, and wherever you look there are digital devices working for us (some would argue that it is we who are working for them).

For consumer voice recording, we have watched the progression from analog reel, to cassettes, to microcassette, to minidisk, and now into the digital realm.
Analog recording machines are difficult to find. Digital recording has become the medium of preference, with its lower distortion, increased battery life, and large memory storage capacity.

From now on, into the future, there is no need for any moving parts, reels, heads, pulleys or tape, for that matter. All of the recorded material is stored completely in memory. It exists only as bits on a hard drive, or a memory stick, or on a memory chip inside a digital recorder.

The lack of a physical recording in the case of recorded material that has evidentiary value, must be compensated for, by including several safeguards against tampering, when designing a digital recorder.

First, the file format within the recorder, and uploadable to a PC, should be of a proprietary format, one that cannot be edited or changed using available software. Also, an embedded time and date signal should be imbedded, or interwoven along with the recorded audio, such that during playback using manufacturer-supplied software, one can observe the date and time of recording as it advances through the file.

There are a number of consumer digital audio recorders on the market. Sony, Panasonic and Olympus are three that come to mind. Each uses a system of folders and files to index recordings. Each has its own proprietary software for reproducing and downloading the files, as well as for converting them to wav (editable) format.


An additional machine, built to more demanding specifications, is the PUMA Police special digital recorder, used by police officers when taking statements from complainants, witnesses and suspects. This machine has a capacity of 44 hours of recording with accessory memory cards, and has built-in noise cancellation.

Any of these machines is fine for making recordings of face-to-face meetings, as well as for recording consensual telephone recordings, using a telephone recording adapter available from Radio Shack. With a voice-activated machine, a telephone line can be monitored and recorded for days, unattended. Before recording, one should check for laws governing recordings in the state in which the recording is to be made.

Some machines offer a choice of quality vs. record time. Even at the highest quality, one can record for hours. Different microphone sensitivity positions are options for when the recorder and microphone are close, or far from the desired conversants,

Once a conversation has been recorded it needs to be converted to a format that is useful and yet retains its evidentiary value. The file, in its proprietary format should be retained in case there is a later challenge of authenticity and completeness.

Additionally, one can produce a WAV file of the recorded conversation. This can then be played on any PC using Windows Media Player Software or special transcription software like WavPedal5. This software allows the computer to be used as if it is a transcription machine, using WAV files instead of cassettes or microcassettes. Using widely available software, CD’s to be used at legal proceedings can be produced from WAV files.

Usually recordings need some degree of enhancement to optimize intelligibility. A conversation recorded in a restaurant will include all ambient sounds in the vicinity of the microphone. The more one can control the location where a recording is made, the better will be the quality of the recording.

Professional Audio Laboratories has developed software and enhancement systems specially designed to optimize digital recordings. We can improve the sound quality, and generate digitally enhanced CD’s containing pertinent conversations that are crisp and audible. Please call with your requirements.
With 31 years experience in the field of recorded evidence, we can provide you with the most expert support in the field of recorded evidence.

(201) 664-8333 - info@proaudiolabs.com
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