Perception thresholds for changes in frequency response

Adapting the frequency response to the preferences of a listener has a variety of applications, like adapting an equalizer for individualized music playback in hearables or finetuning the frequency-dependent gain in the context of hearing aid fitting. For a consistent preference to be developed by the listener, the presented options must be clearly distinguishable. This study analyzes how much gain needs to be applied in an individual frequency band to ensure discriminability. Thresholds are measured for gain applied in different two-octave-wide frequency bands and stimuli. Median thresholds (d’=1.24) are between 3.5 and 7.3 dB for most conditions. Using a noise stimulus, median thresholds tended to be higher for changes at low frequencies and differed little between conditions with positive and negative gains. Using a full sentence as a stimulus, thresholds for positive gains tended to increase with frequency, while thresholds for negative gains behaved non-monotonically. Using a single word as a stimulus, thresholds are much higher than for the full sentence (>9.5 dB).