Use of the MIDI Playback Sequencer as an Aid for Teaching Skills in Harmonic Dictation and Error Detection

Use of the MIDI Playback Sequencer as an Aid for Teaching Skills in Harmonic Dictation and Error Detection.

David A. Stech

University of Alaska Fairbanks

The goal of this project was to create software to help students to learn harmonic dictation and error detection skills more efficiently than is currently possible with LP records, audio cassettes, audio compact discs, or laser discs.

The problem with most recording technology is that the process of cuing a passage for playback requires quite a bit of time by the user. Traditional media does not allow the student to adjust the different parameters of sound playback, such as selecting individual voice lines for closer study, adjustment of playback tempo without distortion of pitch, or direct A-B comparison of two similar music excerpts.

MIDI data files, designed for playback on a sequencer/sound module, are constructed to allow students to have a great deal of operational control over the playback of ear training drill examples, to permit students to design the playback to better serve their individual critical listening needs. It also offers to the instructor the possibility of designing these materials in house without the high production costs of manufacturing laser disks or compact discs.

The UTSA demonstration will illustrate the degree to which playback can be controlled and modified by students using this technology for college-level aural training in harmonic dictation and error detection.The following operations (and perhaps some others) will be demonstrated:

1. Simple playback: The student turns the power to the unit on, inserts a 3.5" floppy disk, puts on a headset, and pushes START to hear the playback. The LED display of the sequencer displays the program number for files on the diskette. (This number is equivalent to the "track" number on a compact disc.) The control functions for simple playback are nearly identical to an audio cassette player. The MIDI can also be programmed by the instructor so that the title of the file can be displayed on thethe top line LCD of the sound module.

2. Change of tempo: The student can change the tempo of playback by pushing either TEMPO (<) or TEMPO(>) on the sequencer. The LCD display scrolls ahead or backward to reflect changes in metronome setting. The tempo change buttons may be engaged at any time, either while the sequencer is standing silent, or while a file is being played back. As indicated earlier, pitch is not affected by a change in the playback tempo.

3. Selecting individual voice lines for playback: Soprano, alto, tenor, and bass voices can be assigned to tracks 1, 2, 3, & 4 to the sequencer/sound module unit. Buttons allow students to activate or mute the note content for any track, or any combination of tracks to permit them to concentrate their attention on that linear part of the harmonic example which is giving them difficulties.

4. Comparison two similar harmonic excerpts: Students who cannot identify the differences between two harmonic excerpts (one with chromatic alteration and one without) can use MIDI playback to directly compare the two different versions: either voice line against voice line, or voice line superimposed over the same voice line in a similar example to hear the difference between the two examples.

The MIDI files created for the UTSA software demonstration were developed using PC-based notation/sequencer software, but similar files may be created by connecting a digital MIDI piano to the MIDI input of the sequencer sound module.

The benefits and limitations of this playback medium are summarized below:

Benefits:

1. The software may be developed by the instructorat a relatively low cost when compared to production of laser discs or compact discs.

2. The student does not need a personal computer to read these files, but instead uses a less-expensive stand-alone sequencer/sound module to play them back.

3. Students do not have to be familiar with MIDI data to use theplayback equipment. Sequencer/sound modules have developed to the point where teachers no longer have to contend with esoteric terminology, suchas square waves, controller waves, voltage-controlled oscillators, etc.

4. The playback/sequencer is less expensive than a personal computer or a laser disk player. Its competitive cost may permit a music department to equip a small laboratory with a number of units for student use.

5. The technology to be demonstrated at UTSA is available on the market now.

Limitations:

1. The quality of synthesized sounds (especially the Acoustic Piano sound patch) is of high quality for student training purposes. Nevertheless, step time entry of pitch and rhythm data can sound robot-like in playback unless the MIDI file creator is willing to do some refinement of the data. Creators for sequencer/sound module software will benefit from some knowledge of the mechanics of MIDI.

2. Students need to be trained as to how to use the playback equipment, if they are to make full use of the options described above.

3. Sequencer/Sound modules are small and can be stolen easily. Some thought needs to be given to securing these units before they can be made available for unsupervised student use.

4. This method of playback has not been tested as to its effectivenessas a learning aid.