In addition to the accompaniment function, it turns out that these hybrid systems in which the acoustic piano can be silenced potentially have another very practical function. If your playing is likely to meet with objections from neighbors or family, being able to silence the piano and then play as loudly as you want, while listening through headphones, can be very handy. Realizing this, the major player-piano manufacturers make the MIDI controller feature available — without the player piano — relatively inexpensively. These MIDI controllers include a MIDI sensor strip under the keys, or optical sensors for keys and hammers, but no hardware and electronics that would make the piano keys move on their own. Usually, these systems come with a "stop rail" or other mechanical device to prevent the hammers from hitting the strings, an internal digital sound source, and headphones. When you move a lever to stop the acoustic piano sound, you turn on the digital sound source, which is heard through the headphones. Yamaha calls this instrument Silent Piano (formerly MIDIPiano). PianoDisc calls their add-on system QuietTime; QRS's version is called SilentPNO. More information about these systems is included in the article "Buying an Electronic Player-Piano System."
But the accompaniment and "silent" functions of a hybrid MIDI controller/acoustic piano are only the beginning of what it can do. Just as the MIDI signal can be sent to a synthesizer or sound card, it can also be sent to a personal computer or transmitted over the Internet. Regardless of whether a MIDI controller originates in an acoustic or a digital piano, it enables the instrument to interact with music software to record, produce notation, control instrumental voices on a personal computer, or interact with other pianos in the same room or on different continents. The potential for hybrids in creating and teaching music is limited only by the imagination of the user. Notation softwares — from MakeMusic's Finale, Avid's Sibelius, GenieSoft's Overture, and others — allow the hybrid piano's key input (playing) to be converted to music notation. This notation can be edited, transposed, split into parts for different instruments, played back, and printed out. The possibilities for teaching are perhaps even more powerful. Taking a lesson from a teacher in a different state or a master class from a performer in a different country becomes possible with hybrid technology, particularly when combined with the player-piano features. Exacting copies of performances can be sent to similarly equipped instruments for playback, and critiques — with musical examples — can be sent back to the student. Some systems enable this interaction in real time over broadband connections, complete with synchronized video.
As we've said, most of the activity in the field of acoustic hybrids has been among player-piano makers, whose offerings have been either specialized (Silent Piano) or add-ons (QuietTime, SilentPNO). However, MIDI capabilities are now standard in all acoustic pianos, vertical and grand, made by Story & Clark, a subsidiary of QRS, the only piano maker so far to have done this. If you add a stop rail to silence the piano (available from QRS) and a sound source, you could turn one of these instruments into a "silent" type of hybrid like those described above. But even without those additions, a Story & Clark piano can be used with a personal computer and music software for recording, notation, controlling computer-produced instrumental voices, or any of the myriad other uses possible with a MIDI controller.
Digital-based Hybrids: Replicating the Acoustic Experience
Now, you may wonder: If you're just going to use a piano to interact with a computer, play piano sounds silently, or make other instrumental sounds, why bother with an acoustic piano at all? Why not just use a digital piano or keyboard of some kind? The reason is: the experience. Digital pianos are long on functionality but short on, shall we say, atmosphere. For those used to the looks, touch, tone, or other, less tangible aspects of acoustic pianos, digital pianos, in their "pure" form, just don't cut it — so digital piano makers have spent a great deal of time, energy, and money trying to mimic one or more of these aspects of acoustic pianos. The closer they get to duplicating the experience of playing an acoustic piano, the more they earn the right to the hybrid designation — because, when you get down to it, the function of an acoustic piano is the experience.
The first aspect of an acoustic piano that digital piano makers mimicked was, of course, the looks, and a large segment of the digital piano market consists of acoustic piano look-alikes. But that alone isn't enough to earn the title hybrid. Next, the mechanism of the acoustic piano found its way into the digital piano. Much engineering has gone into the numerous action designs in digitals, always in the attempt to make their feel and response as close as possible to that of a "real" piano. For example, Yamaha's GranTouch line of digital pianos uses a slightly modified acoustic piano action to trigger the piano's sensors (the hammers are small and don't actually strike strings). With such an action, there's no need to simulate certain action processes, such as escapement, because it actually occurs mechanically. Many digital piano actions these days have weighted and/or wooden keys, and other enhancements that do a reasonable job of emulating an acoustic piano action; still, advanced pianists, especially classical ones, are unlikely to be satisfied by most of them.