Low frequency thresholds assessed with 40 Hz MLR in adults with impaired hearing.

In a group of 30 adults with impaired hearing, objective thresholds defined with 40 Hz middle latency responses (MLR) were compared with subjective audiometric measures. Frequencies of 0.25, 0.5, and 1 kHz were studied. In order to guarantee a good frequency specificity, subjects presenting large high-frequency hearing loss were particularly chosen. The 40-Hz MLR thresholds were generally worse than the audiometric measures. The average difference was around 12 dB, but in about one-third of the cases it was between 20 and 30 dB. Although not perfect, 40-Hz MLR estimates on low frequencies can be very helpful and deserve further consideration, especially in children.