What type of annunciation device produces a vibration in a bed or chair to alert a user?

A tactile device is designed to create a physical sensation that can be felt, such as vibrations or other forms of touch-based feedback. In the context of alert systems, a tactile device that produces vibrations in a bed or chair serves to alert users by stimulating their sense of touch. This type of device is especially useful for individuals who may have impairments in hearing or vision, as it relies on the sense of touch to convey alerts or notifications effectively.

Visual alert devices, while useful for providing information through lights or displays, do not engage users through physical sensations. Auditory alarms rely on sound, which can be ineffective for individuals with hearing impairments, and a contact alert system generally refers to systems that require physical touch to activate alerts rather than providing ongoing vibrational notifications. Therefore, the tactile device stands out as the correct choice for producing vibrations to notify a user through a bed or chair.