What is Resonance?

Every physical space, instrument, and electronic circuit has natural resonant frequencies — frequencies at which it vibrates more efficiently and produces louder output. A room might resonate at 120 Hz due to its dimensions, causing a boomy buildup every time the bass plays a note at that frequency. A snare drum resonates at its fundamental pitch, creating a ringing tone after each hit. A guitar body resonates at frequencies determined by its size and construction. In mixing, resonances are usually problems to be solved. Room resonances in a recording create uneven bass response — certain notes boom out while others disappear. Instrument resonances can create annoying ringing or "wolf notes." Microphone proximity effect creates a resonant-like buildup in the low frequencies. Even plugins and processing can introduce resonant behavior, particularly filters with high Q settings. Identifying resonances requires careful listening and spectral analysis. A resonant frequency often reveals itself as a note that sustains longer than others, a frequency that jumps out unpleasantly on certain notes, or a constant tonal coloration that sounds unnatural. Once identified, a narrow EQ cut at the resonant frequency — typically 3-8 dB with a tight Q — can eliminate the problem without affecting the surrounding frequencies.