Equalization
Equalization (Frequency Balance Adjustment)
The process of selectively boosting or cutting specific frequency ranges in an audio signal to shape its tonal character, fix problems, or match a desired sound profile.
技術的詳細
EQ types include parametric (adjustable frequency, gain, and Q/bandwidth), graphic (fixed frequency bands with adjustable gain), shelving (boost/cut all frequencies above or below a point), and high/low-pass filters (remove frequencies beyond a cutoff). The Web Audio API provides BiquadFilterNode with types: lowpass, highpass, bandpass, lowshelf, highshelf, peaking, notch, and allpass. Each filter is defined by frequency, Q factor (bandwidth), and gain. Multiple filters can be chained. Common applications include removing low-frequency rumble (highpass at 80 Hz), reducing sibilance (notch at 5-8 kHz), and adding presence (peaking at 3-5 kHz).
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) ```