Hardware Recommendations - Technical Considerations

Page Index

• Introduction
• Analog versus digital
• Audio recording
• Digital audio recorders
• Video recording

Introduction

When choosing recording equipment for linguistic fieldwork, one must seek out hardware that records data in portable formats that ensure long-term intelligibility. However, the equipment must also be practical for use in the field. This page outlines the strengths and weaknesses of various types of recording equipment.

Analog versus digital

Analog recorders are inexpensive, and are capable of capturing high quality data. However, they add their own noise to the recording and lack time-coding. Most importantly, the recordings produced by analog recorders are short-lived and the data captured by them is not accessible to any computational analysis. The materials that analog recorders produce, therefore, lack portability and long-term intelligibility.

Digital recorders, on the other hand, come with a variety of options, many of which produce recordings in formats that are quite portable and enduring. When reviewing digital recording devices, it is important to consider whether the data is compressed and which format the data is recorded in.

Audio recording

Recording Equipment: When choosing equipment for field work, look for the following features:

• Digital recorders should have the ability to record in Linear PCM (Pulse Control Modulation), at minimum 16-bit-depth and 44.1 or 48 kHz sample rate, and to store in uncompressed WAV format.
• Digital output. Some devices record digitally, but only have an analog output, which leads to a 3 dB loss in recording quality.
• An external microphone of good quality. A bad microphone can have a worse effect on sound quality than MP3 compression does.
• A suitable power source. Even if electricity is available, it may fluctuate too much to be used for actual recording, but still be fine for recharging a battery. In areas without electricity, rechargeable batteries are useless without solar panels. Find out what sort of conditions to expect and choose a device with an appropriate power source.

Digital audio recorders

Solid state

Solid state recorders produce 16-bit uncompressed pulse code modulation format (PCM) recordings. Because solid state recorders record data in standard formats (such as wav), it is easy to transfer the data to a computer.

DAT

DAT recorders can record up to 120 minutes of uncompressed, high-quality mono audio onto magnetic tape. Migration of data from this recording to a personal hard drive is lossless when good transfer software is used. Unfortunately, portable DAT recorders have become difficult to find, but they are still good choices for field work.

MiniDisc

MiniDisc recorders produce lower quality recordings that are inadequate for detailed acoustic analysis. With the recent exception of the HiMD recorder, MiniDisc recorders compress data. Even the HiMD recorder currently requires expensive special equipment in order to upload the uncompressed file to a computer. Despite their ubiquity and ease of use, MiniDisc recorders are NOT recommended for the recording of endangered languages, because the resulting audio files are unsuitable for long-term preservation.

Hard disk

Hard disk recording devices have recently become available as small USB devices that produce very good recordings. Manufacturers such as USBPre, Digidesign, and M-Audio have developed equipment that record directly to the hard disk of a laptop. Though new, these devices are likely to become more common for field work in the future.

Video recording

When selecting and using video equipment for field work, keep the following points in mind:

• Choose a camera that can record high-quality audio (linear PCM) at a minimum of 44.1 or 48 kHz, and be sure to set the camera to record at that sampling rate (many cameras come with a default setting of 32 kHz). If you must use a camera that does not meet these requirements, then you should use a separate audio recorder to make the sound recording.
• If you can afford it, choose a 3-CCD camera (which has a separate CCD for each of the 3 color planes), rather than 1-CCD, because 3-CCD provides better resolution.
• Use an external microphone of good quality (the built-in microphones are inadequate).
• Always record at SP, not LP.
• Never use the digital zoom function. It's all right to use optical zoom, but be careful -- some cameras switch automatically from optical to digital zoom.
• When filming at night, it's better to switch the night shot setting to Off, because it emits enough light to make you think you're getting good video when you're actually not.
• When framing the shot, hold the camera far enough away to entirely capture all gestures made by the speaker.

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