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Frequency-following responses to 500-Hz tone bursts presented to the left ear and 540-Hz tone bursts presented to the right ear were recorded from human subjects. Recordings were made both under monaural and binaural conditions. The responses summed over monaural conditions (for left and right ear stimulation) were larger than the responses obtained in the binaural condition. This binaural interaction shows that the frequency-following response reflects binaural processing probably occurring at or below the level of the inferior colliculi.Nous avons enregistre chez un certain nombre de sujets normaux les reponses reproduisant la frequence (FFR) a des «tone-bursts» de 500 Hz, presentes a l'oreille gauche et des «tone-bursts» de 540 Hz presentes a l'oreille droite, dans des conditions soit monaurales, soit binaurales. Les reponses ont presente une amplitude plus grande dans les conditions monaurales que dans les conditions binaurales. Il semble done exister une interaction binaurale qui montre que la repons...

Binaural beats have been investigated in normal volunteers using high-stable synthesizers. There are considerable differences between the subjective rhythm heard and the difference of the two frequencies, indicating that this dissimilarity must be caused centrally.

Binaural beats that result from low‐frequency sinusoids, one to each ear, are not nearly as prominent as monaural beats. However, when in‐phase noise N0 is added to the sinusoids, the stimulus changes back and forth between N0‐S0 and N0‐Sπ, and the binaural beats are quite noticeable.

This study concerns the masking of binaural beats between a pure tone, stimulating one ear, of f0 + d frequency (d = 3 Hz) and the differential sound originated in the other ear by stimulation with the mixing of 2 pure tones of frequency f1, f2 (f2 – f1 = f0). The masking sound is a third-octave filtered white noise, of nominal frequency fn variable between 200 and 4000 Hz, and sound pressure also variable. For each fn and for each constant value of f0, f1, f2, the minimum sound pressure level of the narrow-band noises for masking the beat is measured as a function of the frequency fn; the sound pressure level of the pure tones is maintained constant at 45 dB. The minimum sound pressure level of the narrow-band noises for masking the normal beats (a pure tone of 315 Hz at the left ear, of 318 Hz at the right ear) is also determined. The latter measurement gives, as expected, a very deep minimum at 315 Hz; from the other measurements it results some oscillations of experimental values, with a mean value ge...

The diagnosis of cortical brain impairment by means of the visual negative after-image was conducted in earlier experiments, with gratifying results. 3 The Archimedes spiral was used in these investigations to produce the perceptual after-image. The over-all plan was, however, to select or develop a battery of tests which would yield high validity and reliability without requiring too much time to be practicable for inclusion in routine diagnostic examinations. For many reasons the Graham Kendall Memory-for-Designs 2 was selected for investigation and possible inclusion in the diagnostic battery. This test includes a positive after-image, the factor of learning, motor pathways in the drawing of the stimulus forms, a measure of psychomotor coordination, etc. The addition of this test with the Spiral test did raise the diagnostic validity in the determination of cortical brain damage. 1 Problem The possibility of the use of other sensory modalities was then considered, resulting in

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A reduction in the use of opioids by older adult patients could reduce unpleasant side effects for them. During general anesthesia, binaural beat (BB) listening has been found to reduce intraoperative fentanyl consumption as well as postoperative pain scores and discharge time. Auditory BBs are a perceptual phenomenon occurring when tones of 2 slightly different frequencies are presented simultaneously and separately to each ear.The study intended to evaluate the ability of BBs, as a nonpharmacological premedication, to reduce postoperative morphine consumption in older adults undergoing total knee replacement surgery and to modify the levels of anxiety and feelings of pain that patients experience.The research team designed a prospective, single-center, randomized controlled study.The study was conducted in the Orthopedic Department of the Santa Maria Maddalena Hospital (Volterra [Pisa], Italy).Forty older adults at the hospital who were undergoing total knee joint replacement with spinal anesthesia participated in the study.The study included 2 groups (n = 20 each), one receiving BBs stimulation with frequencies of 256 Hz in one ear and 260 Hz in the opposite ear producing a BB of 4 Hz (intervention group), and the other receiving acoustical stimulation at 256 Hz in both ears (control group). BBs, or acoustical stimulation, were administered before the surgical procedure. Both acoustical stimuli, generated with the Gnaural program, were delivered through stereo headphones connected to a laptop in the preoperative holding area.The study measured postoperative, cumulative, self-administered morphine consumption, in mg, through a patient-controlled analgesia device. Feelings of anxiety were also assessed using the State-Trait Anxiety Inventory, and feelings of pain were measured every 8 h during the first postoperative day using a numerical rating scale.Patients who received the intervention, consumed almost half of the dosage of morphine during the first postoperative day when compared with the control group's consumption, 5.75 mg ± 5.25 vs 11.85 mg ± 7.71, respectively. The consumption did not correlate to anxiety measures. Regarding pain perception, no differences between the groups were captured.BB stimulation before surgery can be successfully used as a nonpharmacological treatment to reduce morphine consumption in older adults who undergo knee replacement. The use of a noninvasive, safe, and inexpensive BB intervention can result in a positive effect on patients' postoperative recovery.

Responses of low-frequency neurons in the inferior colliculus (IC) of anesthetized guinea pigs were studied with binaural beats to assess their mean best interaural phase (BP) to a range of stimulating frequencies. Phase plots (stimulating frequency vs BP) were produced, from which measures of characteristic delay (CD) and characteristic phase (CP) for each neuron were obtained. The CD provides an estimate of the difference in travel time from each ear to coincidence-detector neurons in the brainstem. The CP indicates the mechanism underpinning the coincidence detector responses. A linear phase plot indicates a single, constant delay between the coincidence-detector inputs from the two ears. In more than half (54 of 90) of the neurons, the phase plot was not linear. We hypothesized that neurons with nonlinear phase plots received convergent input from brainstem coincidence detectors with different CDs. Presentation of a second tone with a fixed, unfavorable delay suppressed the response of one input, linearizing the phase plot and revealing other inputs to be relatively simple coincidence detectors. For some neurons with highly complex phase plots, the suppressor tone altered BP values, but did not resolve the nature of the inputs. For neurons with linear phase plots, the suppressor tone either completely abolished their responses or reduced their discharge rate with no change in BP. By selectively suppressing inputs with a second tone, we are able to reveal the nature of underlying binaural inputs to IC neurons, confirming the hypothesis that the complex phase plots of many IC neurons are a result of convergence from simple brainstem coincidence detectors.

When two pure tones of slightly different frequencies are delivered simultaneously to the two ears, is generated a beat whose frequency corresponds to the frequency difference between them. That beat is known as acoustic beat. If these two tones are presented one to each ear, they still produce the sensation of the same beat, although no physical combination of the tones occurs outside the auditory system. This phenomenon is called binaural beat. In the present study, we explored the potential contribution of binaural beats to the enhancement of specific electroencephalographic (EEG) bands, as previous studies suggest the potential usefulness of binaural beats as a brainwave entrainment tool. Additionally, we analyzed the effects of binaural-beat stimulation on two psychophysiological measures related to emotional arousal: heart rate and skin conductance. Beats of five different frequencies (4.53 Hz -theta-, 8.97 Hz -alpha-, 17.93 Hz -beta-, 34.49 Hz -gamma- or 57.3 Hz -upper-gamma) were presented binaurally and acoustically for epochs of 3 min (Beat epochs), preceded and followed by pink noise epochs of 90 s (Baseline and Post epochs, respectively). In each of these epochs, we analyzed the EEG spectral power, as well as calculated the heart rate and skin conductance response (SCR). For all the beat frequencies used for stimulation, no significant changes between Baseline and Beat epochs were observed within the corresponding EEG bands, neither with binaural or with acoustic beats. Additional analysis of spectral EEG topographies yielded negative results for the effect of binaural beats in the scalp distribution of EEG spectral power. In the psychophysiological measures, no changes in heart rate and skin conductance were observed for any of the beat frequencies presented. Our results do not support binaural-beat stimulation as a potential tool for the enhancement of EEG oscillatory activity, nor to induce changes in emotional arousal.

Binaural beats utilize a phenomenon that occurs within the cortex when two different frequencies are presented separately to each ear. This procedure produces a third phantom binaural beat, whose frequency is equal to the difference of the two presented tones and which can be manipulated for non-invasive brain stimulation. The effects of binaural beats on working memory, the system in control of temporary retention and online organization of thoughts for successful goal directed behavior, have not been well studied. Furthermore, no studies have evaluated the effects of binaural beats on brain connectivity during working memory tasks. In this study, we determined the effects of different acoustic stimulation conditions on participant response accuracy and cortical network topology, as measured by EEG recordings, during a visuospatial working memory task. Three acoustic stimulation control conditions and three binaural beat stimulation conditions were used: None, Pure Tone, Classical Music, 5Hz binaural beats, 10Hz binaural beats, and 15Hz binaural beats. We found that listening to 15Hz binaural beats during a visuospatial working memory task not only increased the response accuracy, but also modified the strengths of the cortical networks during the task. The three auditory control conditions and the 5Hz and 10Hz binaural beats all decreased accuracy. Based on graphical network analyses, the cortical activity during 15Hz binaural beats produced networks characteristic of high information transfer with consistent connection strengths throughout the visuospatial working memory task.

It has been suggested that children who are unable to make simple and complex auditory discriminations or who are unable to perceive phoneme blending in words will have difficulty in phonics reading programs [NINDS Mongr. No. 9 (1969)]. Forty normal‐hearing reading‐impaired children with normal SRTs were given phonetically balanced words monaurally at 60 dB HL. Words were next presented to one ear at 10 dB SL and to the other at 40 dB SL. The later was altered so that all energy above 1.5 kHz was effectively attenuated. Intelligibility was determined for temporarily distorted speech (as in words “sounded out” and words with one or more missing phonemes.) JNDs for pitch and loudness were obtained with a reference tone of 1 kHz at 60 dB HL. The perception of binaural beats at 0.5 kHz was also noted. It was observed that reading‐impaired children yielded normal speech discrimination scores but typically poor binaural scores. Difficulty in perceiving the temporarily altered and/or phonetically deleted speech was also significant for the poor readers. Pitch, intensity, and beat perception were found to be unimpaired. Errors found in listening were primarily restricted to the consonants, while errors in oral reading tended to be chiefly vowels. That is, vowels were usually heard correctly but read incorrectly. Types of errors and relation to orthography are discussed.

A comparison is made between the limits for the detection of binaural beats and the limits for the detection of binaural “fusion.” The functions obtained for these two phenomena appear to be independent.

We present here a model which simulates some recent findings [S. Kuwada et al., Science 206, 586–588 (1979); S. Kuwada et al., Neurosci. Abstr. 76 (1979)] in which the interaural phase sensitivity of inferior colliculus neurons has been studied using interaural delays or binaural beats. The cyclic response patterns of some neurons are altered systematically as a function of stimulus off‐time and interaural intensity differences. In addition, the response to binaural beat stimuli indicates that some cells are sensitive to the direction of interaural phase change. The model is comprised of two inputs (one from each ear), each with crossed collateral inhibition. The two inputs synapse on a third cell, resulting in four synaptic connections; two inputs are presynaptic inhibitory and two are direct excitatory. At each junction, simple rules about transmitter release, transmitter supply, and changes in membrane potential are made. Manipulation of these parameters allows for simulation of the commonly seen cyclic response pattern as well as some of the unique effects of off‐time, interaural intensity differences, and sensitivity to a particular direction of interaural phase change. [Supported by NIH grant NS12732.

Subjects were asked to match a stationary, monaural, “repetition noise” waveform with a sinusoidal waveform presented to the contralateral earphone. The repetition noise waveform was filtered (900–5000 Hz), and had a fixed repetition rate (147, 293, 587 rps). Both the signal and the noiae were maintained at overall levels of approximately 52 dBA. All subjects found strong relationships based upon binaural beats at frequencies corresponding to small integer (1, 2, 3, 4) multiples of the repetition rate. Weaker relationships were found at fractional multiples of the repetition frequency. The perceptibility of frequencies corresponding to certain aspects of the temporal microstructure of the “noise” waveform was also investigated. [This research was supported by a grant from the National Institute of Mental Health.]

Many low‐frequency inferior collicular neurons respond cyclically as a function of interaural delay. Since the interval between peaks of this cyclic function equals the period of the stimulating frequency, then these neurons must be sensitive to phase differences created by varying the interaural delay. Binaural beat stimuli also create a changing phase difference and thus should yield similar response patterns to those found to varying interaural delay. This is in fact the case. Almost all neurons which respond cyclically to interaural delays will also respond similarly to the beat frequency stimulus. Furthermore, the maximal discharge for both types of stimuli occurs at the same phase difference. We have studied neurons which can faithfully follow beat frequencies as high as 70 Hz. The use of binaural beats has the added advantage over interaural delay stimuli in that it provides the opportunity to study the dynamic aspects of a simulated sound source in space, i.e., the responses of neurons to moving sound in different directions and different velocities. In fact, we have studied neurons that respond only when the simulated sound source (via beat frequency) is moving in a particular direction and others that respond maximally to a particular velocity.

(1948). About the Question of Binaural Beats. Acta Oto-Laryngologica: Vol. 36, No. sup78, pp. 150-150.

Historically, the phenomenon of binaural beats has been considered to be a strong indication of binaural beats has been considered to be a strong information. Usually, one listens to the beats with bilaterally matched sound‐pressure levels (zero interaural intensity difference). However, in investigating the limits of dichotic intensity which permit binaural beats, it was noted in the present study that subjects respond to the presence of beats whenever the tones to both ears are above threshold. The frequency range investigated was 100 to 2000 cps. As other authors have previously reported, the best performance occurred in the 500‐ to 600‐cps range. It is obvious (after the fact) on the basis of any of several of the popular schemes used for representing binaural interaction that the binaural beat should follow a physiological rather than a physical logic. The case for separate timing channels in the auditory nervous system is thus further strengthened. The phenomenology of the “unbalanced beat” and implications for pitch theory as well as for binaural interaction theory are discussed.

Activity of superior olive of Nembutal‐anesthetized cats was recorded with bipolar electrodes (100μ 12 mm apart) to a binaural‐beat stimulus paradigm. The binaural‐beat rate was represented in the recorded activity as a periodicity of the “following” response envelope. A measure of the proportion of this activity that may be considered as physiological interaction, rather than the summation of the two independent monaural responses, was obtained by subtracting, on a CAT computer, responses evoked by monaural stimulation of the two ears from the responses recorded during binaural stimulation. The activity remaining (physiological interaction) resembles an amplitude‐modulated sinusoid having a frequency of approximately (f1+f2)/2 and an envelope periodicity corresponding to the binaural‐beat rate. The extent of interaction varied with base frequency and intensity, with interaural differences in frequency and intensity, and with the level of anesthesia. This interaction was found only in a discrete region of...

The question is sometimes raised as to whether the temporal aspects of acoustic signals are analyzed solely at the basal end of the organ of Corti. Three series of experiments were performed on the differential masking of stimuli known to be analyzed by the auditory system on the basis of temporal characteristics. First, a masking‐level difference (MLD) experiment was performed. Binaural masked thresholds (under S0 and Sπ conditions) of a 500‐Hz tone were measured and compared to similar thresholds taken while a loud high‐pass noise, cut off at 800, 1000, 1200, 1600, 2400, or 4800 Hz, was simultaneously presented. Any basal cochlear contribution to the MLD was predicted to be at least partially disrupted by the extra masker (since it would be serving to keep the high‐frequency segments of the basilar membrane busy). Similarly, perception of the Wood effect (a monaural phase effect) and of binaural beats was tested with and without such high‐pass bands of noise. Except for those cutoff frequencies that allowed noise energy to interfere directly with the signal, the influence of the extra masking was negligible. Because a fatigued ear might behave differently, the experiments were repeated following intense high‐frequency exposures (and, in one case, with a subject having a precipitous high‐frequency hearing loss). The results were similar. Implications of these findings are discussed. [Investigation supported in part by the National Institute of Neurological Diseases and Blindness, National Institutes of Health, U. S. Department of Health, Education, and Welfare.]