: Instead of trying to encode every high-frequency detail (which would require more data), the encoder only records the lower frequencies.

: At 48kbps, you can expect a high-frequency "roll-off" around 11–13 kHz , which is sufficient for clear voice and background music, though some "underwater" artifacts may be audible in complex tracks.

: It then includes a small amount of "helper" data that allows the player to reconstruct the high frequencies during playback, simulating a full-range sound.

: You can store roughly four times as much audio compared to a standard 192kbps MP3 while maintaining reasonable intelligibility.

: This allows for near-CD quality speech and acceptable music quality at very small file sizes, making it ideal for mobile data streaming and voice memos. Technical Context for "48kbps"

When M4A files are encoded at low bitrates like 48kbps, they typically utilize . A specific feature of this technology is Spectral Band Replication (SBR) :