Digital Audio Basics

To operate Reason's synthesizers, you'll need to understand at least one key concept: waveforms.

Though invisible, sound waves are just like any other kind of wave. They can be described by their length, height (amplitude), and speed (frequency), and no two waves are exactly alike. The unique combination of length, amplitude, and frequency makes up a sound wave's shape, or waveform.

As you can imagine, sounds bouncing around and interacting in the real world can have some pretty complex waveforms. That's why we use samplers in Reason to capture the character of not just the unusual, but of even the everyday sounds we want to use in our music.

But Reason and other synthesizers are also able to generate very simple, or "pure," waveforms (sine, sawtooth, triangle, and so on) that can't be found anywhere in nature. Using these pure waveforms has come to be known as FM or analog synthesis. This synthesized sound has a distinctive character that's become almost synonymous with techno music, and is typically described as "warm" and "rich."

Reason's instruments use both kinds of sounds, allowing you to combine sampled sounds and generated (synthesized) sounds to produce your own unique ones.

Digital audio and sampling

Before you jump into creating sounds in Reason and storing them on your hard drive, you also should understand a little about how audio samples are converted from sound to computer data.

Converting sound waves to digital information means taking a series of "snapshots" of a waveits length and height at a particular time. These snapshots, or samples, are stored together and can then be played back to re-create the sound. The more individual samples you take, the better your re-creation will be.

Sampling rates

Faster sampling can store higher frequencies and produces more-faithful sound reproduction. Sampling formats and rates can vary in digital music, and you will have some choice as to what quality you want to use to store your audio. For example, CD audio means sampling 44,100 times a second (44.1 kHz), and then playing back at the same rate.

The trade-off with very high sampling rates is that better quality means bigger files to store and more processor speed consumed for playback. But if you have space on your hard drive (and most computers come with multigigabyte drives), high sampling rates are well worth it. Many of today's audio cards and hardware can even capture and play back at up to 96 kHz. Keep in mind, though, for burning an audio CD of your music you will need to "downsample" your music to 44.1 kHz at some point, and this may not justify the storage space and processor load required by higher rates.

Dynamics and bit depth

Dynamics are louds and softs over time, and even the most complex waveforms have peaks and valleys (louds and softs). Bit depth represents how many different louds and softs your sample contains. Think of bit depth as vertical notches measuring waveform height as a sound plays. The more notches, the more smoothly the louds and softs get captured by the sampler.

Bit depth, or sample size, is just as important as sampling rate in preserving audio quality: Louds and softs get forced to the closest value allowed at a given bit depth. So at a low bit depth, the original sound gets squished to a fairly uniform height, which makes for noise and distortion. CD-quality audio has a bit depth of 16, which does little or no damage; most people don't even notice a difference. However, 8-bit sampling will add significant, noticeable noise and distortion. Lower bit depths do result in much smaller files, but these days that isn't an issue for most people.

If you're finicky about holding on to as much fidelity as you can, you should archive your audio at the highest possible sampling rate and bit depth, even if you later have to downsample for output to CD. If your sound card and driver settings are optimized (see Chapter 2, "Installation"), you can capture your Reason tunes at bit depths of up to 24 and sampling rates up to 96 kHz.