To conclude, I will first discuss the possible future directions of the Squeezables and then summarize the work done.
Many lessons can be learned from the various instruments or interfaces discussed in the introduction. The lessons could be incorporated into the future versions of the Squeezables. One of them is to measure the distance between every one of these Squeezables. Though this may fall into the "many body problem " in physics where solving for the resultant or exact equation is virtually non-existent, the ability to even know where the neighboring Squeezables are could be very useful information in music. In STEIM, the MIDI-Conductor used ultrasound to measure distance between two hands which may result in the interruption of the ultrasonic beams from hands and blind spots. The possibility of fan-out or wide angle ultrasonic beams could be useful to achieve measurements of distance among multiple Squeezables. These wide ultrasonic beams could also be used to transmit the different states of the Squeezables, making them wireless. Infra-red beams can also be used for higher transmission bandwidth.
Another direction would be to extend the capabilities of the Squeezables to include other classes of tactile features and even "free-air" movements (Fig. 1.1). Incorporating haptic or force-feedback mechanisms, like vibrators and actuators into the Squeezables would also give more information to the users about the systems they play, or even allow the Squeezables to deform into other shapes for different hands and preferences.
Imagine a classroom of the future where children would pick up the Squeezables and learn about the foundations of music and sound or even to use the Squeezables as tools for their music projects. Another example application would be a room full of Squeezables, where the performers can pick up one or two of his choice and start to move and squeeze them around in the air. The performers could even jump into a pool of these Squeezables like the Musical Play Pen. With built-in 3-axis accelerometers like the Hands from STEIM and Digital Baton from the Brain Opera, the free movement in the air or the body movement in the pool can be measured and used to control other aspects of music, like beats, rhythms and intensity.
The Digital Maracas have handles that are only used for holding the accelerometers. These handles could well be transformed into Squeezables, expanding the Digital Maracas into the "squeeze" category in the taxonomy of hand interface (Fig. 1.1).
With future parasitic power, i.e. electricity harnessed from wasted energy like walking, bouncing a ball or squeezing, the issue of power will no longer be important. This parasitic power can also be used to directly alter the power of a radio-frequency transmitter, allowing the Squeezables to have varying transmission distance, affecting surrounding Squeezables differently, depending on their power. Thus, this "artifact" of parasitic power would become an expressive variable in such a squeezable interface.
At this time, the sound produced by the Squeezables comes from external synthesizers and speakers. It is possible to house a synthesizer on a chip and embed it into each and every Squeezable. Miniature speaker technology that allows sounds to be amplified and reproduced at the source will enable Squeezables to have multiple sound colors and spatialization.
With mappings that incorporate learning algorithms, the Squeezables could be able to adapt to different squeezing/playing styles, i.e. they could become a musical instrument that learns the behaviors of users.
From the very first version of the Squeezables to the last, I have looked into many kinds of materials and sensing methods. Various kinds of materials have been used for creating and shaping the Squeezables. The versions that had liquid in a polyurethane tube had the best shape and flexibility but also had some disadvantages. It helped to identify problems with sensing when there is water and where leakage is a constant issue.
Foam is a light and flexible material that made it suitable to create the Squeezables. The best thing about foam is that it has no leakage problem. With a cube-like pressure sensor, many foam balls can be placed on the faces forming a squeezable cluster that has multiple continuous controls on one interface.
Three major issues evolved from the squeezable cluster.
First, the lack of sensitivity of the foam cluster became apparent when children with little hands started to squeeze just one ball among the cluster. Second, the flaking and tearing caused me to look into materials that will protect the foam. Lastly, it became clear that it was desirable to turn the Squeezable from a one person interface into a group play instrument.
With the making of the Pole of Squeezables, besides addressing all the issues, a new feature was added : pulling. Each foam ball is sensitive to being squeezed independently, protected by decorative cloth and can be pulled from its station at the top of the pole. There are seven of these balls on the station and they retract to the station when released. They can also be squeezed as a collective like the Squeezable Cluster, and they have the ability to form irregular shapes through different configurations of the balls.
Two other observations were made about the Pole of Squeezables : foam balls are too light and do not have enough tactile response and the pole is too high for children or shorter people to reach.
The Table of Squeezables, about 40 cm high, gives children much easier access to the balls. With gel material in insulating latex and decorative cloth, these Squeezables have much more mass and flesh-like response. It had six balls on the table top that retracted when released. Irregular shapes could also be formed with different configurations. With better pull sensors, the balls were more responsive to pulling and lifting.
The creation of the Squeezables gave the electronic music world a new and standalone controller with multiple continuous controls within a single interface. Hopefully, it will evolve into an auxiliary controller to enhance traditional discrete input devices like keyboards. With the Table of Squeezables, a new instrument that supports group play is born, suitable for both young and old. A group play instrument lets the team players respond to one another's playing habits and encourages team work while learning to anticipate what others will do. Unlike the theremin or "free-air" instruments, Squeezables are physical interfaces that give users tactile feedback when playing, while retaining the freedom of movement and gesture so attractive to all of us.