A prospective, randomised, controlled study examining binaural beat audio and pre-operative anxiety in patients undergoing general anaesthesia for day case surgery.

Pre-operative anxiety is common and often significant. Ambulatory surgery challenges our pre-operative goal of an anxiety-free patient by requiring people to be 'street ready' within a brief period of time after surgery. Recently, it has been demonstrated that music can be used successfully to relieve patient anxiety before operations, and that audio embedded with tones that create binaural beats within the brain of the listener decreases subjective levels of anxiety in patients with chronic anxiety states. We measured anxiety with the State-Trait Anxiety Inventory questionnaire and compared binaural beat audio (Binaural Group) with an identical soundtrack but without these added tones (Audio Group) and with a third group who received no specific intervention (No Intervention Group). Mean [95% confidence intervals] decreases in anxiety scores were 26.3%[19-33%] in the Binaural Group (p = 0.001 vs. Audio Group, p < 0.0001 vs. No Intervention Group), 11.1%[6-16%] in the Audio Group (p = 0.15 vs. No Intervention Group) and 3.8%[0-7%] in the No Intervention Group. Binaural beat audio has the potential to decrease acute pre-operative anxiety significantly.

Effects of the menstrual cycle on the human acoustic reflex threshold.

Contralateral acoustic reflex thresholds (ARTs) were determined daily in 10 normal women and 10 men, aged 18-24, in response to a broad-band noise, over a 32-day period. Mean ARTs for men vs women over the period differed by only 1.55 db, but for women a stimulus level of about 6 db more was required to elicit ART over Days 1-6 of the menstrual cycle than over Days 7-26 (p less than .01). There was furthermore an increase in sensitivity in the luteal phase (Days 15-19) of the cycle. It appears that the changes in ART throughout the cycle mirror, and may reflect, concomitant changes in the hormonal (estrogen and progesterone) levels. Changes in ART over the cycle may thus be explained by hypothesizing that the ART is an aspect of sensorineural behavior affected by hormonal concentrations to which a number of other auditory phenomena are known or thought to be related.