Volume adjustment in hearing aids is a key feature that allows the user to increase or decrease sound amplification to suit their needs. Most hearing aids allow manual volume control: through a button, a wheel or other types of physical adjustment devices, the user can adjust the volume to increase or decrease the sound amplification in real time. It is also possible to set personalised programs: the audiologist or other hearing professional will program the hearing aid based on specific needs (for example, the adjustment of the frequency response curve and general amplification), taking into account the user's preferences and hearing loss. Hearing aids can also be adjusted via remote controls (for example, a mobile application or remote control), allowing the user to adjust the volume and settings directly from their mobile device. Finally, some hearing aid models automatically change their settings based on the surrounding environment.