Delay is one of the most popular effects produced by tape recorders, and has been used on countless recordings since the 1950s. Simple delay effects are easy to create, easy to hear, and fun to work with, especially for younger students. You can create delay effects in several ways, including acoustically and with tape recorders, but here we'll focus on two digital approaches: MIDI delay and digital audio delay.

With MIDI delay, you duplicate a MIDI track's note data and then offset the copy by some specific amount of time, providing an echo effect. If, however, you create just one delay, and the notes are allowed to sustain, the synthesizer must play twice as many notes (the original and the delayed copy), halving its polyphony. In addition, MIDI delay is far less subtle and flexible than audio delay. For those reasons, when affordable audio-delay hardware became available some 15 years ago, MIDI delay became obsolete in recording studios.

FIG. 1: Here we have a simple MIDI delay effect, shown in Cakewalk Sonar Producer. Track 2 is a copy of track 1 and is offset by an eighth-note. The mixer window shows track 2’s volume level as 50, which is half of track 1’s volume level.

MIDI delay still has its uses in school labs, though. A primary advantage of MIDI delay is visual feedback: younger students better understand how delay works when they can see the delay track and control the track volume and placement the same way they control other tracks. Furthermore, when teaching with simple slap delays, there is no need for audio-delay parameters such as early reflections and wet/dry mix.

Here's how to create a simple delay effect using MIDI tracks. For this example, I'll use the round, “Are You Sleeping?”. First, record the melody on track 1 using a percussive sound, such as marimba. That type of sound makes it easy for students to hear the delay effect. Copy track 1 to track 2, and then shift track 2 and back by an eighth note. Be sure to activate your program's Snap to Grid feature and set it to eighth-note increments so that the track will move to the precise location.

If you play both tracks at that point, you will perceive a reiteration effect instead of a delay; it will sound as though you played two eighth notes for every note you actually played. To create a delay effect, lower the volume of track 2 to emulate the way acoustic sounds reduce in volume when they reflect off of a surface. The easiest way to do that is to assign track 2 to a different MIDI channel, and then lower the new track's volume level. For instance, if track 1's volume level is set at 100, try setting track 2's level to 50 (see Fig. 1).

You can create a syncopated effect by reversing the volume levels: set the level for track 1 to 50, and that of track 2 to 100. You can also add a spatial dimension by adding reverb to track 2 or by panning the two tracks hard left and hard right. If you want to create the classic stereo ping-pong delay effect, copy track 2 to track 3, assign track 3 to a different MIDI channel, and pan track 1 center, track 2 left, and track 3 right. (If you create a ping-pong effect with “Are You Sleeping,” try setting the delay amount to 16th notes instead of 8th notes.) You can also produce a musical-round effect by moving the first note of track 2 to measure 4, and the first note of track 3 to measure 6.

Finally, have your students experiment with using different musical intervals and different sounds (harp, pizzicato strings, and so on) for the delay tracks. Technically speaking, the resulting sounds aren't delays, but they can be useful musical textures for reinforcing rhythm.

Most audio recording software includes audio delay effects. With extensive modulation capabilities, multiple delay taps, and a variety of parameters that simulate the behavior of sound in an acoustic space, audio delay is far more complex and subtle than MIDI delay. This ability to simulate the behavior of acoustic sounds makes audio delays an effective teaching tool for older students. I won't get into audio delay in any detail here, because it's a deep subject. Suffice it to say that it's well worth becoming familiar with the delay effects provided in your recording software and keyboard synths.

Note, however, that if you use hardware synthesizers or samplers to play MIDI tracks, you first need to rerecord the MIDI tracks as audio tracks. To do that, solo each MIDI track so that your synthesizer just plays that track, and then record the audio output of the synthesizer to a new audio track. Repeat this process for each MIDI track that you plan to convert to audio. Once the MIDI tracks are converted, you can mute them and work just with audio, including adding audio effects. Many software instruments can convert tracks from MIDI to audio without playing back the tracks one by one in real time — a nice time-saver.

While older students may be ready to explore the depths of audio delay effects, young students learning the basics of song production don't need all of those options. For them, MIDI delay is a good place to start. Whichever method you choose, be sure to show your students how to enhance their music with this basic but important effect.

For information on Don Muro's books and music, visit www.donmuro.com.