Output spectra of each hearing aid (HA) for inputs consisting of a sinusoid (left) and a tone produced by a flute (right).

The sinusoid had a frequency of 3 kHz (vertical dashed line), corresponding to a brief portion of a sweep encompassing the frequency range 0.1–10 kHz. The flute note was C5 (fundamental frequency: 523.3 Hz). In both panels, the black line shows the spectrum from the Phonak HA with NLFC, and the gray line shows the spectrum from the Widex HA with LFT. The gray dashed line in the right panel shows the averaged spectrum from both HAs without frequency lowering.