Control of responding by the location of sound: role of binaural cues.
Both ears must hear together for accurate sound-side choices; loudness alone is not enough.
01Research in Context
What this study did
Researchers taught rats a left-or-right lever game. A buzz came from either side.
Press the lever under the speaker, get food. Wrong side, nothing.
After the rats were perfect, the team cut one ear’s input. They wanted to know if the animals still tracked the louder ear or if they needed both ears working together.
What they found
With one ear blocked, the rats fell apart. Accuracy dropped to chance.
When both ears were open again—or both were blocked—the rats were fine.
The brain needs matching input from two ears, not just the louder one, to know where a sound lives.
How this fits with other research
Reed et al. (2003) later showed rats can learn speech-like sounds using rise-time, a timing cue. Both studies use the same go-left/go-right DTT, proving the procedure works for different auditory dimensions.
SLOANE (1964) trained pigeons on a flicker-rate line and saw the gradient slide with each new S-. The 1985 paper adds a spatial line—left to right instead of slow to fast—showing the same continuum rule holds across senses.
Christophersen et al. (1972) used airflow as the cue and got fast learning. The 1985 study says airflow would fail if you block one nostril, because symmetry, not strength, drives the discrimination.
Why it matters
When you teach a child to turn toward a speaker or find who is talking, check both ears. If one side is weak, louder won’t help; you need to train with both ears active or teach a different cue. Try seating the child straight ahead and use visual prompts until binaural input is equal.
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Join Free →Before starting a ‘find the sound’ program, quickly screen each ear with a quiet click—if one side is weaker, add bilateral amplification or switch to a visual cue first.
02At a glance
03Original abstract
In auditory localization experiments, where the subject observes from a fixed position, both relative sound intensity and arrival time at the two ears determine the extent of localization performance. The present experiment investigated the role of binaural cues in a different context, the sound-position discrimination task, where the subject is free to move and interact with the sound source. The role of binaural cues was investigated in rats by producing an interaural imbalance through unilateral removal of the middle auditory ossicle (incus) prior to discrimination training. Discrete trial go-right/go-left sound-position discrimination of unilaterally incudectomised rats was then compared with that of normal rats and of rats with the incus of both sides removed. While bilateral incus removal affected binaural intensity and arrival times, the symmetry of sound input between the two ears was preserved. Percentage of correct responses and videotaped observations of sound approach and exploration showed that the unilateral rats failed to localize the sounding speaker. Rats with symmetrical binaural input (normal and bilaterally incudectomised rats) accurately discriminated sound position for the duration of the experiment. Previously reported monaural localization based upon following the intensity gradient to the sound source was not observed in the unilaterally incudectomised rats of the present experiment. It is concluded that sound-position discrimination depends upon the use of binaural cues.
Journal of the experimental analysis of behavior, 1985 · doi:10.1901/jeab.1985.43-315