Neural Representation of Loudness: Cortical Evoked Potentials in an Induced Loudness Reduction Experiment.
Florian H Schmidt, Manfred Mauermann, Birger Kollmeier
PMID 31994456WHAT IT FOUND
In 12 normal-hearing adults, a loud preceding tone made a later identical tone seem quieter.
An early brain response, N1-P2, tracked that perceived loudness, while later responses did not.
Key findings
01A preceding loud tone made the later target tone seem quieter, and the effect grew as the inducer-target gap increased.
02As the inducer-target gap increased, mean N1-P2 amplitude decreased, and N1-P2 amplitude correlated with loudness matches.
03Latencies did not correlate with loudness matches, and the amplitude effects were significant only for mean amplitudes, not peak-to-peak amplitudes.
STILL TO COME
How it was doneWhat they found
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What it does not show
Only 12 subjects were tested, and the authors note high variability between subjects in this kind of loudness experiment. The participants had clinically normal hearing, so it does not show how these effects appear in patients. The task used simple tone pulses and a laboratory loudness-matching procedure, not everyday sounds or clinical assessment. The EEG analysis used a low-pass filter that reduced amplitudes and made separate examination of N1 and P2 difficult. The study measured correlations between brain responses and loudness judgments, not whether changing the brain response changes loudness. The psychoacoustic task produced alpha waves during EEG recording, which the authors describe as a drawback of measuring brain responses and loudness judgments at the same time.
Declared interests
The study was funded by Deutsche Forschungsgemeinschaft. The paper does not report other conflicts of interest.
The easy way to misread this
Do not read this as evidence that EEG can assess loudness problems in patients. The study tested 12 adults with normal hearing in a tone-matching task, and the reported correlation was between a laboratory loudness match and an EEG amplitude, not a clinical outcome.