Many who love to play also love to sing, and the digital piano has something for vocalists as well. Many instruments now feature a microphone connection. In its most elementary form, this simply uses the digital piano's audio system as a PA for vocals. But some models throw the full weight of their considerable processing power behind the vocalist. Many vocal recordings and performances take advantage of effects processing to enhance the performer's voice. This can range from adding reverberation to effects that completely alter the performer's voice, making it sound like anything from Barry White to Betty Boop. Top-of-the-line digital pianos can even go beyond what some recording studios can do. Perhaps even more amazing is the ability of some instruments to combine the vocal input with their ability to harmonize, resulting in your voice coming out in four-part harmony. Display of karaoke lyrics is also common; the presence of a video output on some instruments allows the lyrics to be displayed on a TV or other monitor.
When an acoustic player piano plays, the keys must move in order for the hammers to strike the strings and produce sound. The digital piano does not share this mechanical necessity, yet we now have digital pianos whose keys move when playing a recording. You'll recall from the section on recording that the digital piano can record and reproduce your playing, or can reproduce a MIDI file from another source. The sounds are produced by sending the playback data directly to the tone-production portion of the instrument, bypassing the keyboard. But since there is no dependency on moving keys, why go to the extra expense of making them move? Two reasons: First, it's one way for the instrument to direct beginners to the next melody note in the educational modes of some models, as described earlier under "Educational Tools." Second, it's just fun to watch. However, you should measure the value of this feature against the additional cost, and be mindful of the increased possibility of mechanical failure due to the additional moving parts of the key-drive mechanism.
Human Interface Design
The Man-Machine Interface, or MMI, as designers and engineers typically refer to it, defines how the player interacts with the instrument's controls. All of the amazing capabilities of the modern digital piano are of little value if the player can't figure out how to use them, or can't access them quickly while playing. The considerations here are the location, spacing, grouping, size, shape, colors, and labeling of the controls. Take the example of the rhythm break discussed earlier. Its purpose is to alter the rhythm during playing. If the button that activates this feature is inconveniently located, small, and surrounded by closely spaced buttons of a similar size, shape, and/or color, its usefulness is severely limited. If, however, it's within easy reach of the keyboard, of decent size, and somewhat distinctive in appearance or markings, it becomes a useful tool.
In the case of instruments with displays, considerations include the size, resolution, and color capabilities of the screen and — more important — the logic behind its operation. Two types of screen interfaces are currently used on digital pianos: touchscreens and softkeys. Most readers are already familiar with touchscreens from ATMs and other modern institutional uses. The term softkeys doesn't refer to the feel of the keys, but to the fact that their functions are displayed on the adjacent screen, and change depending on the operation being displayed by the screen. This is as opposed to hardkeys, which have a single dedicated function. Each method has its proponents, but the interface type is less important than the MMI design. A smaller monochrome display that you can intuitively understand is better than a large color display that makes no sense to you.
Also worth considering is the placement of connections you'll use often. If you frequently switch back and forth between speakers and headphones, you'll want to make sure the headphone jack is easy to locate by sight or feel, and that the cord will be out of your way when plugged in. If you'll be using a USB memory device to transfer files between instruments or between the instrument and a computer, make sure the USB port is easy to get to. In newer designs, a USB port is placed above the keyboard level for easy access, as opposed to earlier models in which the port was below the keyboard or on the instrument's rear panel.
We can't leave the subject of user interfaces without discussing the owner's manual. As with the MMI itself, a well-written manual can make it a pleasure to learn a new instrument, and a bad manual can be worse than useless. This is particularly important for higher-end instruments. Fortunately, many manufacturers allow you to download the manuals for their instruments. This lets you compare this critical aspect of the instruments you're considering. The manual should be thoroughly indexed, and clearly written and illustrated. Third-party tutorials are available for some instruments, especially the more complex models. These tutorials step you through the model's functions with audio or video instructions, and provide an alternative to sitting down with the manual.