Another gadget from Etsy.

Rarebeasts writes:

The SwoofTronic SB is a small hand held electronic instrument that allows you to change the frequency, filter value and noise preset value of a basic sound wave.

This device consists of two small controller boxes joined by a cable, one controller goes in each hand and each controller has a light sensor in the top. As you let more light onto the left hand sensor you increase the frequency (pitch). As you let more light onto the right hand sensor you increase the value of the active filter on the middle stage. A switch built into the LED of the left hand piece changes the value of the final noise stage.
The 8 preset final stage values include:
1. None - Noise interference off
2. BasicOn - Noise on constant
3. Saw - Saw tooth interference
4. Sine - Rough sinewave pattern
5. OnOffSlow - Slow 50% duty cycle
6. OnOfffast - Fast 50% duty cycle
7. WaveSlow - Strobe with slow PWM
8. WaveFast - Strobe with fast PWM

Link: Rarebeasts

This is one from my collection of noise based stuff.

The SwoofTronic Pi is a small handheld device that allows you to change the frequency and duration of a basic sound wave using your thumbs to control light sensors.

This item consists of two small boxes joined by a cable. One box goes in each hand and each box has a light sensor in the top, as you let more light onto the Right hand sensor you increase the frequency (pitch). As you let more light onto the Left hand sensor you increase the length of the note played.

The interesting noises are made when you speed up the timing of the notes by blocking off all light into the left box. As the output is modulated between left and right output channels, speeding up the note repetition makes strange strobe effects.

There are three ways to trigger the light sensors, each have different effects on the sound. (1) You can use the ambient light in the room and control the level by blocking off the sensor with your thumb. (2) You can use the built in LEDs(light emitting diodes)in the centre of each box which can be used to trigger the sensor of the box on the other side. (3) A small LED keyring can also be used.

It's a fun little instrument.