Filtering
Filtering is an operation that eliminates certain frequencies from a sound. A sound results from a large number of components vibrating simultaneously at different frequencies. The outcome of these vibrations is what we call the timbre of a sound. Filtering therefore changes a sound’s timbre.
The type of filtering presented here is Band-Pass filtering.
To use it, first choose the frequency area you want to work on (low, mid, or high), then set the bandwidth around the central frequency. Depending on the chosen bandwidth, only selected frequencies are allowed to pass while all others are removed. Filtering can thus radically alter a sound’s timbre.
• Used dynamically, filtering lets you sculpt the sound and play with the appearance or disappearance of certain frequencies.
• Used statically, filtering can remove unwanted frequencies from a sound’s spectrum (for example, correcting a poorly recorded track that contains too much low-frequency energy).
Unprocessed original sound: Waves
Exploring Band-Pass Filtering
Spectrogram of a Band-Pass Filter
Depending on the register in which it operates, filtering can enhance or neutralize a sound’s sense of “presence” (mids), remove high components, reinforce existing lows, and so on. As early as 1950, electroacoustic composers made extensive use of filtering and discovered that its powerful action could completely transform a familiar sound, allowing only a tiny, previously unheard portion to remain.