Frequency Selectivity Flashcards
What are the two side effects of non linearity?
Suppression and distortion.
- -> Suppression refers to the situation in which the tone reduces the response of another tone at the best place of the basilar membrane.
- -> Distortion is observed when two or more frequency components interact on the Basilar Membrane, creating lower-frequency inter modulation products called combination tones.
What shows a high degree of tuning?
At the base of the cochlea (high characteristic frequencies) a single place on the basilar membrane shows a high degree of tuning at low levels (narrow bandwidth).
How are tuning properties of the basilar membrane reflected in the auditory nerve?
Tuning properties of the basilar membrane are reflected in the tuning properties of the auditory nerve and at higher centres in the auditory system.
At higher centres neurons with different characteristic frequencies can converge and produce neurons with complex tuning curves.
In the apex of the cochlea where are tuning curves narrow?
Tuning curves are narrower at the apex-with low characteristic frequencies when measured in terms of absolute bandwidth in hz but broader as a proportion of characteristic frequency.
How is frequency selectivity enhanced at the base?
It is enhanced by an active mechanism; which depends on the motion of the outer hair cells. Which effectively amplify the response to low-medium level frequency components close to the characteristic frequency.
How can frequency selectivity in humans be measured?
It can be measured using masking experiments.
Our ability to detect a signal in the presence of a masker depends on how close the two sounds are in frequency.
What is an excitation pattern?
It is a plot of outputs of the auditory filters as a function of centre frequency, in response to a given sound.
An excitation pattern is a representation of the overall activity of the basilar membrane as a function of characteristic frequency.
