Devices with stereo speakers deliver sound from independent channels on both left and right sides, creating a richer sound and a better experience.
The lowest frequency at which the device produces audio. The lower the low-frequency response, the stronger and juicier the bass.
An amplifier is integrated into the device. An audio amplifier takes a small signal and makes it bigger without making any other changes in it which results in better sound, so any sound source can be connected to speakers.
Devices with a subwoofer have a higher quality, deeper bass.
A passive radiator is a type of driver (speaker) that doesn't have a voice coil and a magnet. The sound vibrations produced by a passive radiator depend on its mass and the size of its enclosure. It is usually used in combination with a woofer to produce deep bass tones.
The highest frequency at which device produces audio. The higher the high-frequency response, the clearer and crispier the treble.