The authors determined the ability of two old-world non-echolocating bats, Eidolon helvum and Cynopterus brachyotis, to use binaural time and intensity difference cues for localization. The bats were trained to localize pure tones throughout most of their hearing range from loudspeakers located 30 degrees to the left and right of midline. Both species easily localized high frequency tones, indi...

1) Oster’s idea was to use the perception of binaural beats as a diagnostic tool because some people are unable to perceive and respond to them. Oster never mentions brainwaves or entrainment as a function of binaural beats. This is interesting since nearly every company advertising binaural beats claims Oster invented binaural beat brainwave entrainment. 2) People with certain neurological con...

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 audi...

The primary purpose of the present experiment was to test whether the binaural equal-loudness-ratio hypothesis (i.e., the loudness ratio between monaural and binaural tones presented at the same Sound Pressure Level, SPL, is independent of SPL) holds for hearing-impaired listeners with bilaterally symmetrical hearing losses. The outcome of this experiment provided a theoretical construct for mo...

The auditory octave illusion arises when dichotically presented tones, one octave apart, alternate rapidly between the ears. Most subjects perceive an illusory sequence of monaural tones: A high tone in the right ear (RE) alternates with a low tone, incorrectly localized to the left ear (LE). Behavioral studies suggest that the perceived pitch follows the RE input, and the perceived location th...

Although many studies have explored the relation between reaction time (RT) and loudness, including effects of intensity, frequency, and binaural summation, comparable work on spectral summation is rare. However, most real-world sounds are not pure tones and typically have bandwidths covering several critical bands. Since comparing to a 1-kHz pure tone, the reference tone, is important for loud...

Unlike humans, not all mammals use both of the binaural cues for sound localization. Whether an animal uses these cues can be determined by testing its ability to localize pure tones; specifically, low frequencies are localized using time-difference cues, and high frequencies are localized using intensity-difference cues. We determined the ability to use binaural cues in 2 New World bats, Phyll...

Binaural hearing involves using information relating to the differences between the signals that arrive at the two ears, and it can make it easier to detect and recognize signals in a noisy environment. This phenomenon of binaural hearing is quantified in laboratory studies as the binaural masking-level difference (BMLD). Mandarin is one of the most commonly used languages, but there are no pub...

Many cells in the inferior colliculus (IC) are sensitive to interaural time differences (ITDs), in the form of an oscillatory dependency of average firing rate on ITD. We studied the degree of damping in such binaural responses, recording from neurons in the inferior colliculus of pentobarbital-anesthetized cats to binaural broadband noise and tones. Noise-delay functions and composite curves w...

The psychophysical detection threshold of a low-frequency tone masked by broadband noise is reduced by < or = 15 dB by inversion of the tone in one ear (called the binaural masking level difference: BMLD). The contribution of 120 low-frequency neurons (best frequencies 168-2,090 Hz) in the inferior colliculus (ICC) of the guinea pig to binaural unmasking of 500-Hz tones masked by broadband nois...