A combined band located there broadens, and 1136, 1061, 1045, and 1029 cm−1 frequencies in its high-frequency component are assigned to Fe O H vibrations in spinel whereas a 1003 cm−1 frequency located in its low-frequency component is attributed to the vibration of a Cr–O bond.
The study results show that weak characteristic frequency component located in low-frequency area can be extracted gradually from strong noise background owing to the energy transfer mechanism from high-frequency area to low-frequency area, as a result, a novel low-pass filter can be achieved ultimately.
Thirdly, an analysis was made of the relationship between the two effects in the experimental database, with it being found that the highest degree of agreement, or the joint highest frequencies, are located in the optical mass range mr ∈ [1.0, 1.2] and the clearness index range of Kt ∈ [0.8, 1.0].
Its purpose is to raise the energy for those frequency components located in the high-frequency domain in order that those formants can be extracted in the high-frequency domain.
For example filter 2, k damp_c < 0, while the resonance frequency is located in the high region (f r = 2.34 kHz).
For example filter 1, k damp_c > 0, while the resonance frequency is located in the low region (f r = 1.40 kHz).
We further provide evidence that pitch misjudgment does not occur in temporal concurrence with the repetition of the whole scale, but according to whether the main perceived frequency is located in the sensitive range of auditory perception or not.
Case 1.1: If k damp > k damp_c > 0, the resonance frequency is located in the low region (f r < f s/6), and k damp_c > 0 is satisfied, so a pair of open-loop unstable poles is produced.
