inertial In classical physics and special relativity, an inertial frame of reference (also called inertial reference frame, inertial frame, inertial space, or Galilean reference frame) is a frame of reference that is not undergoing any acceleration ...

audio effects controller is an electronic device that senses changes in acceleration, angular velocity and/or a magnetic field, and relays those changes to an effects controller. Transmitting the sensed data can be done via wired or wireless methods. To be of use the effects controller must be connected to an

effect unit An effects unit or effects pedal is an electronic device that alters the sound of a musical instrument or other audio source through audio signal processing. Common effects include distortion/overdrive, often used with electric guitar in ele ...

so that an effect can be modulated, or connected to a

MIDI controller A MIDI controller is any hardware or software that generates and transmits Musical Instrument Digital Interface (MIDI) data to MIDI-enabled devices, typically to trigger sounds and control parameters of an electronic music performance. They mos ...

musical keyboard A musical keyboard is the set of adjacent depressible levers or keys on a musical instrument. Keyboards typically contain keys for playing the twelve notes of the Western musical scale, with a combination of larger, longer keys and smaller, sho ...

. The Wah-Wah effect is a classic example of effect modulation. An inertial audio effects controller can be compared with a traditional

expression pedal An expression pedal is an important control found on many musical instruments including organs, electronic keyboards, and pedal steel guitar. The musician uses the pedal to control different aspects of the sound, commonly volume. Separate expres ...

to explain what it does. An inertial effects controller uses an inertial sensor to detect user directed changes, whereas a traditional expression pedal uses an electrically resistive element to detect changes. There are some advantages and disadvantages between the two. The main advantages of inertial control versus a traditional foot pedal, are an increased range of dynamic motion, remote control, finer modulation precision and software enabled features such as motion triggered

ADSR envelope ADSR may refer to: * ADSR envelope (attack decay sustain release), a common type of music envelope * Accelerator-driven sub-critical reactor, a nuclear reactor using a particle accelerator to generate a fission reaction in a sub-critical assembly ...

s and bi-directional motion control. The main disadvantages are the requirement for a power source and a more complicated setup. Due to their functional similarity with traditional expression pedals, they have been given the informal name, 'Expression box'.

Availability

Conceivably any or all of the inertial sensors (

accelerometer An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...

gyroscope A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rota ...

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...

), could be used for effect modulation. However, currently the only commercially available products use acceleration sensing only or acceleration combined with angular velocity, as sensed by a gyroscope.

Future

Inertial control of an audio device, wired or wireless, is a relatively recent and growing trend as technology advances have reduced pricing and size as well as improved usability and performance of the core components. Specifically the core components are an inertial device called a Mirco- Electro-Mechanical-System (

MEMs Microelectromechanical systems (MEMS), also written as micro-electro-mechanical systems (or microelectronic and microelectromechanical systems) and the related micromechatronics and microsystems constitute the technology of microscopic devices, ...

), a

microcontroller A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable i ...

, and for wireless systems, a radio frequency transmitter/receiver.

References

{{reflist Audio engineering Effects units