Voice recorder sound: quality vs. quantity

Digital voice recorders can cost less than $40 or well over $400. While other factors -- such as ease of use and memory capacity -- come into play, what really sets digital voice recorders apart is the quality of the recordings they make.

Most digital voice recorders give you the choice of recording at two or three (or sometimes even six) levels of quality. Keep in mind that when a manufacturer says the model's memory can hold "up to 50 hours," that's at the lowest level of quality. Compression and the sampling rate both factor into the equation. If you are just recording voice notes to yourself, you're not going to need a larger sampling rate because human voices operate within a fairly narrow frequency. However, if you are recording in a large room or for broadcast, or you want to include music, then you'll want to use a higher sampling rate.

Normal speech and other sounds are analog (continuous) in nature. To convert sound into a digital signal that can be stored by the recorder or processed by a computer, a digital voice recorder has to take a series of samples of that sound. The higher the sampling rate, the more accurate the reproduction of the original sound. Of course, storing more samples takes up more memory.

Compression, on the other hand, works to reduce file sizes by getting rid of some data, instead of relying on various mathematical tricks to reproduce that information based on other information in the audio file. Highly compressed files, such as those recorded in the DSS (used by Olympus and Philips high-end models) or LPEC (used by Sony) file formats, are significantly smaller than files recorded in either the WAV or MP3 formats, which use less compression.

Boiled down to its essence, you'll be able to fit more in a recorder's memory if you record at a lower-quality setting (high compression and lower sampling rate) than if you want the very best and truest audio quality (low compression, high sampling rate). Most recorders have at least some on-board memory. Others have memory card slots, letting you add memory (as high as 32 GB) and allowing you to swap out one card for another once it is filled. Some models combine the two, offering some on-board memory plus card slots.

Analog tape recorders are still being made and are an option if you need to archive recordings on tapes. Olympus and most top makers of digital voice recorders still sell these cassette recorders, which are inexpensive and sometimes easier to operate than digital models.

Generally, people who do a lot of dictation or interviews find digital recorders better because they are able to edit and organize files on a computer, send them electronically to a transcriber or use voice recognition software to convert audio into text. Some digital voice recorders let you use keywords to search the recording and find the part you want to hear again. Because they are designed specifically to record the spoken word, digital voice recorders make higher-quality recordings than you'll get from something that's integrated into an MP3 player or cell phone or smartphone, though these devices are an option if all you need is something to record an occasional reminder or an amateur interview.

Here's what reviewers say are the most important things to consider when shopping for a digital voice recorder:

  • Sound quality. Basic voice recorders generally record at up to a 44 kHz sampling rate, good enough for audible playback for personal use. Those hoping to broadcast their recordings will want a recorder that can record at a higher rate, such as 96 kHz. You can also enhance sound quality, if needed, by using an external microphone. Windscreens will limit noise on outdoor recordings.
  • Physical characteristics. All digital voice recorders are portable, but some are a little clunkier than others. The more you'll be toting your digital recorder around, the smaller and lighter you'll want it to be and the longer you'll need the battery to last. If you will be using it in rough conditions, you will also want to consider its ruggedness and build quality.
  • Memory. If you plan mainly on making low-fidelity voice recordings, all digital voice recorders will have plenty of memory for hours of recording. If you want to record at higher-quality settings, or in stereo, you'll need to consider memory a bit more carefully. If you're not sure how much memory you'll need, choosing a model with memory card slots, a feature that is more and more common, will give you the flexibility to upgrade.
  • Editing features. Some digital voice recorders are designed simply to record audio, requiring you to do most of the work of editing and managing files on your computer. However, if you need to edit on the recorder itself, pay attention to its on-the-fly editing and navigation features, like the ability to bookmark key passages or, even better, offer keyword search for a specific word or phrase.
  • Compatibility with your computer. All recorders work with Windows systems, and most current models have now added Windows 7 compatibility. Most recorders -- but not all -- use file formats that can be played back in any media player. If you have a Mac, look carefully to see if a recorder uses non-standard file formats that might require special software for playback or file conversion. Such software is not always Mac-compatible.

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