Voice Recorder Sound

The trade off between quality and quantity

Digital voice recorders can cost less than $40 or well over $400. While other factors -- such as ease of use -- come into play, what really sets them 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 when using 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 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). For instance, the Olympus WS-331M (*Est. $115), which has a relatively ample 2 GB of on-board memory, offers six recording modes. At the highest quality, you'd be able to fit about 35 hours of stereo audio on the recorder, while recording on the lower settings nets about 500 hours of mono audio. Most recorders have at least some on-board memory. Others have memory card slots, letting you add memory as needed 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, however, 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, though the latter are an option if all you need is something to record an occasional reminder or an amateur interview.