From Spoken Word to Digital Audio File


The illustration above at the top of this page lays out all the possible steps from a conversation to an archived disk. I wish it were simpler.

All the links in the chain

Sound from a conversation is recorded, and becomes digital (if it wasn’t already born that way), and then the digital audio file is recorded onto a CD. The steps in the chain follow that general path, but there are variations in the exact equipment used to get you there.

Microphone

A microphone (or set of microphones) captures the sound and converts it to an electrical signal. The strength of that signal is lower than your standard audio signal (such as, say, what is driven to your earphones from an earphone jack). Microphones (or mics, pronounced “mikes”) come in a dizzying array of offerings, each designed for different recording environments, and to pick up sounds in different ways.

Pre-Amplifier

(Usually included in a recorder, but sometimes not.) A preamp is used to boost the microphone’s low signal (called mic level) to the same strength of signal that is used in standard audio equipment (called line level; a headphone port on audio equipment is line level)

Most recording devices, if they take microphone input, have a pre-amp inside of them. Some devices will record audio at line level, and need to have an external preamp. Also, you may read of hear discussion about “quiet preamps”—in that usage, quiet is good. That’s because you don’t want to add noise to the signal at the same time that you boost it from the “quieter” level to line level.

Recorder

Here are a ton of different options. Magnetic tape (often cassette) to minidisc to digital storage formats—flash memory media (non removable or removable), to internal disk drive (iPods, iRiver, Cowan iAudio, Archos Gmini). Lots to choose from, here. Things to weigh and matters to hem and haw over. (I really wish this part were easier and slam dunk.)

USB Device

An external device (or external sound card) that converts audio signal from microphone or a recorder into digital format. Plug in a microphone or a tape recorder in one end, plug the other end into your computer.  May or may not be necessary, depending on the rest of your setup.

Computer

Sometimes your computer is the recorder, other times it is what receives and processes the audio recorded elsewhere. The computer is the place where you’ll burn audio and data CDs of your interviews.

CDs/DVDs

Not all disks are alike. Gold CDs use a substance that is longer lasting than other formats. After going to all this trouble, you want your disk to last, don’t you?

Different audio configurations, explained

That animated illustration shows the different ways to put together an audio recording system. Here’s a bit more explanation of each:

USB Mic + Computer

The shortest route is a USB microphone to a computer. The audio is “born digital” by the time it leaves the microphone, and the computer is the recording device. I guess there’s a pre-amp inside the microphone.

Standard Mic + USB Device + Computer

Use any microphone, plug it into a USB device plugged into a computer. The computer is the recording device.

Standard Mic + Recorder + Computer

Use a microphone plugged into a recorder, and directly transfer audio from the recorder to the computer. This works in two ways:

If the audio is born digital, you transfer the audio from the recorder to the computer using a form of file transfer, usually through a USB connection, though it can be Firewire as well.

If the audio is analog, or you’re doing an analog transfer from the headphone port to your computer’s audio in jack, you’ll be playing the recording on the recorder while simultaneously recording it onto your computer. I’ve used this method with cassette tapes and with older forms of minidisc.

Standard Mic + External Preamp + Recorder + Computer

This is similar to the previous system except that it adds an external preamp. It also happens to be my system setup. I’ve got an audio recording device that records line-line audio—it doesn’t have a mic port—so I have a box with a built-in preamp that works with my recorder.

If it’s got a USB, it’s digital

Just a note about USB. Whatever the device, if it has a USB port to it, then the signal leaving the device through that port is digital. If you’re trying to tell the difference between one kind of thing and another, the plugs and ports are a guide for you: If it has analog plugs (headphone jack or minijack), the signal is analog. If it has USB or Firewire or the flash memory itself, then the data is digital.

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