Audiobaseband

Audiobaseband is a term used in audio engineering and communications to denote the unmodulated, baseband representation of an audio signal. In this sense, it refers to the portion of the signal's spectrum that occupies frequencies at or below the carrier frequency in a hypothetical baseband, typically extending from near 0 Hz up to approximately 20 kHz for human-audible content.

Technically, baseband signals are contrasted with passband signals, which are translated to higher frequencies through modulation. The audiobaseband of standard consumer audio is often sampled for digital processing at rates such as 44.1 kHz or 48 kHz, which, according to the Nyquist theorem, preserve the content up to about 22.05 kHz. In analog processing, audiobaseband signals are often passed through anti-aliasing and reconstruction filters to limit bandwidth and prevent distortion.

Applications include digital audio workstations, streaming codecs, and telecommunications systems where the audio is transmitted or stored in baseband form before any carrier modulation or multiplexing. In radio and wireless contexts, the audiobaseband is often the input to a modulator that shifts the spectrum to a desired channel, while in local networks it may be carried as a baseband signal over compatible media.

Relation to baseband: The term emphasizes that much of the audible content is contained in the low-frequency portion of the spectrum, and that later stages may convert it to a different frequency range for transmission or processing. The concept is foundational in digital signal processing, sampling theory, and audio codec design.

Related topics include baseband, baseband signaling, digital audio, PCM, and anti-aliasing filtering.