Apparatuses and methods to sense proximity of an object and operate a proximity sensor of a portable device. In some embodiments, a method includes receiving an ambient light sensor (ALS) output, and altering, based on the ALS output, an effect of a proximity sensor output on control of a proximity determination. The ALS sensor and the proximity sensor may be located adjacent to an earpiece of a portable device. In some cases, the proximity determination may be a proximity of an object to the proximity sensor, and altering the effect may include changing the proximity of the object from a proximity greater than a first threshold to a proximity less than the first threshold. Other apparatuses and methods and data processing systems and machine readable media are also described.