I made a helmholtz resonator by myself and played its resonace frequency sound to it. Obviously, the resonator resonated and near the open end of resonator, I could feel wind. So I placed candle near the opening to see the strength of wind. Surprisingly, If decibel of soundwave was constant, the candle's movement was constant. Which means, the angle of tilted fire was constant. What I thought was that when a material is resonating, It's amplitude of vibration continues to increase although the external soundwave's amplitude is constant. Isn't it true? If it is true, Why was the strength of wind constant? ( the lump of air near opening of Helmholtz resonator also goes under harmonic motion.)( For sure, the lump of air oscillate at resonance frequency.) Isn't wind strength a velocity of fluid? So if wind strength is constant, it means that frequency and velocity of lump of air is constant. right?? other than that, is it the flow rate(N) that affects movement of fire or velocity of fluid?