Comparison Sony ICD-PX470 vs Sony ICD-PX440

A slot for a memory card allows you to expand the recorder's own memory with interchangeable cards (and in some models , recording is only made on such cards, they do not have their own memory). This feature also makes it easier to share data with other devices equipped with a card slot: for example, by inserting a card from a voice recorder into a laptop card reader, you can immediately listen to the material recorded on it or transfer it to a hard drive without fiddling with cables. Cards of the same type usually differ in volume and, accordingly, in cost, which allows you to choose the best option in terms of the ratio of these parameters.

The built-in microphone type determines the mode (number of channels) in which the voice recorder records sound.

— Mono. The simplest option: one microphone that records sound in mono format, i.e. without separation into left and right channels. It is impossible to provide a "surround" sound with such a recording, however, in the case of voice recorders, this is not decisive, because. usually in such a recording it is not the volume of the sound that is important, but the intelligibility of speech — and it is fully provided by a monophonic microphone.

— Stereo. In this case, a pair of microphones is usually used, spaced apart on the sides of the case; the sound is recorded in stereo, and the volume of the sound is achieved due to the difference in the sound reaching the left and right microphones. Considered somewhat more advanced than mono, although it does not provide better speech intelligibility by itself.

Separate input for connecting an external microphone. See "Connecting an External Microphone" for details.

— MP3. The most common digital audio format today, supported by the vast majority of digital audio devices, regardless of size. Provides medium quality compression and medium sound quality. When saved, it compresses information with loss of quality, but these losses are almost imperceptible to the ear, especially when recording speech from a non-specialized microphone.

— WMA. Format developed by Microsoft. It surpasses MP3 in terms of data compression capabilities, providing good quality at a low bitrate and, as a result, a small file size, but is less popular, in particular, due to sensitivity to errors in the file. At the same time, it is very common in digital audio equipment, it can be reproduced on computers without problems (it is a standard audio format of Windows OS).

— WAV. Technically, it is not a format, but a "container" into which you can "pack" sound processed by any codec; however, it is most commonly used to store uncompressed PCM audio. Thus, WAV provides the best sound quality comparable to Audio CD, however, such files, usually, take up much more space than in the above-mentioned formats. It also plays on a computer without any problems.

— Own. Some voice recorder models record audio in their own format, which is different from common standards. Technically, a proprietary format can provide a good r...atio of recording quality to file size, however, listening to such materials often causes inconvenience: you either need to listen to it on the recorder itself, or install a special player or codecs on your computer, or convert it into one of the "generally understood" formats with possible quality loss.

The higher the amount of data per unit of time that is used to transmit the audio stream, the higher the quality of the MP3 recording is provided. So, the base bitrate of 32 Kbps means encoding one second of sound using 32 thousand bits of information - it is used only for speech transmission. Much more common in portable audio recording devices is the recording quality of 128 Kbps, 192 Kbps and 256 Kbps. The maximum possible bits rate for the MP3 format is 320 Kbps. The pursuit of the highest quality of sound recording makes sense for advanced models of recorders; for a conditional voice recorder for recording lectures, the basic bitrate parameters will be quite enough. Also keep in mind that the quality of sound recording affects the size of the resulting files and the duration of the voice recorder.

Uncompressed WAV provides the best sound quality among common Hi-Res audio formats. Its sampling rate is usually 96 or 192 kHz with a bit depth of 24 bits. The format is used for "clean" sound recording with maximum detail of the scene.

The maximum continuous recording time for the voice recorder. It depends primarily on the amount of memory (see "Built-in memory", "Memory card slot"), it is also directly related to the recording quality: the higher the quality, the more space the material occupies and the shorter the maximum recording time. In this regard, manufacturers usually indicate in the specifications the maximum possible recording time, that is, the recording time with minimum quality; with higher quality and time will be less.

The maximum number of folders that can be created in the recorder's memory to store recorded materials. This allows you to organize the materials and makes it easier to find the right record: for example, in journalistic work, the material on each individual topic can be stored in the appropriate folder. Many voice recorders allow you to change the folder used for recording on the fly, literally at the touch of a button.

The range of sound frequencies that the recorder is capable of perceiving and recording. A person is able to hear sound on average from 16 Hz to 20 kHz, but the range of the actual human voice is much narrower — approximately 100-3500 Hz. Therefore, if you plan to use a voice recorder to record speech, these frequencies will be enough. If the purpose of the recorder is not limited to this, you should pay attention to models with a wider range — and in this case, the wider it is, the fuller and richer the recording will be.