Real-Time Tonal Masking Curves
Real-time tonal masking and threshold-of-hearing curves in the spectrum analyzer demonstrates where a dominant tone is audibly masking other frequencies and noise, providing a clear visual correlation of measurements to audibility.
This helps identify the cause of audible distortion. For example, if a speaker is failing a production line perceptual Rub & Buzz test, masking curves can be used to drill down into the cause of the distortion. Simply play a fixed frequency (e.g. 1kHz) sine wave through the signal generator to produce a FFT spectrum, and add a masking curve. The masking curve combines the masking from the fundamental with the threshold of hearing to replicate what the ear hears. It automatically tracks the dominant tone in the acoustic signal and harmonics above the masking and threshold-of-hearing curves are clearly visible. Harmonic cursors identify the individual harmonics for simple interpretation. With the masking curve applied, frequencies and levels can be adjusted in real time to observe the impact.
This tool is also valuable for R&D applications. For example, during component selection, it can help balance component quality or size with cost, to avoid audible distortion while not over-designing to reduce inaudible distortion.
