Abstract: Techniques and devices are described for generating modified audio signals. The techniques include receiving an audio signal at a device, tracking a movement of the device, generating a first modified audio signal to spatialize the audio signal, generating a second modified audio signal to spatialize the audio signal, causing the first modified audio signal to be rendered using a first speaker of the device, and causing the second modified audio signal to be rendered using a second speaker of the device. In some cases, the first modified audio signal is generated using a first head-related transfer function (HRTF) and the movement of the device, and the second modified audio signal is generated using a second HRTF and the movement of the device, where the second HRTF is different from the first HRTF. Numerous variations and configurations will be apparent in view of this disclosure.

Abstract: An exercise treadmill having a direct drive AC induction motor controlled by an AC motor driver/controller. The driver/controller is itself controlled through programmable circuitry having a display and keyboard with user input options. The controller receives signals from a speed sensing device attached to the AC induction motor to maintain the rotational speed of the AC motor within preselected limits. The AC induction motor is attached to one or more flywheels and directly engages, through a drive roller, a walking belt. The matched combination of an AC motor driver/controller with appropriately sized flywheels allows utilization of a variable speed AC induction motor for the direct drive of the treadmill belt.