Sample Rate
Sample Rate (Sampling Frequency)
The number of times per second that an analog audio signal is measured (sampled) when converting it to digital form, expressed in Hertz (Hz). Higher sample rates capture higher frequencies.
技術的詳細
According to the Nyquist-Shannon theorem, a sample rate must be at least twice the highest frequency to be captured. Human hearing ranges up to ~20 kHz, so 44,100 Hz (CD standard) captures up to 22,050 Hz with headroom for the anti-aliasing filter. Common rates include 8,000 Hz (telephony), 22,050 Hz (AM radio quality), 44,100 Hz (CD), 48,000 Hz (video/broadcast standard), and 96,000/192,000 Hz (high-resolution audio). The Web Audio API's AudioContext defaults to the system's native rate, typically 44,100 or 48,000 Hz. Resampling between rates requires interpolation.
例
``` Sample rate standards: 8,000 Hz — Telephone (max 4 kHz audio) 22,050 Hz — AM radio quality 44,100 Hz — CD audio (captures up to 22 kHz) 48,000 Hz — Video/broadcast standard 96,000 Hz — High-res audio production Nyquist: sample_rate ÷ 2 = max capturable frequency 44,100 Hz ÷ 2 = 22,050 Hz (above human hearing ~20 kHz) ```