Auditory brainstem response at the detection limit.
Specific predictions regarding the level dependence of auditory evoked responses near the detection limit were made in a companion modeling study (Lütkenhöner, J Assoc Res Otolaryngol 9:102-121, 2008). Here, these predictions are experimentally tested for auditory brainstem responses (ABR) to Gaussian-shaped 4-kHz tone pulses (full width at half maximum = 0.5 ms) that were presented at sound levels close to the subjective threshold. In the average of over about one million stimulus repetitions (repetition period = 16 ms), the amplitude of ABR wave V showed a smooth transition from a proportional to a logarithmic growth with increasing sound intensity. The latter type of growth corresponds to a linear increase with respect to sound level measured in decibels. Alternatively, the ABR amplitude near the detection limit may be considered a linear function of sound pressure, although-according to the model-this is only an approximation. Data and model are consistent with the view that a sensory threshold does not exist for the auditory modality, in accordance with signal detection theory. Even so, the model may be used to define a quasithreshold that is comparable to the subjective threshold.
Lütkenhöner
Bernd
B
Section of Experimental Audiology, ENT Clinic, Münster University Hospital, Kardinal-von-Galen-Ring 10, 48129 Münster, Germany. Lutkenh@uni-muenster.de
Seither-Preisler
Annemarie
A
D000161:Acoustic Stimulation; D000328:Adult; D001309:Auditory Threshold / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008959:Models, Neurological; D011237:Predictive Value of Tests; D011571:Psychoacoustics; D055815:Young Adult