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(TRE-0748) Phase Information in Hearing

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The Role of Phase Information in Frequency Discrimination

Principal Investigator:
Tobias Reichenbach PhD

James Hudspeth

Contact Information:
Clinical Research Support Office
The Rockefeller University
1230 York Avenue
New York, NY 10065
Telephone: 1-800-RUCARES
Enrollment Status:
Closed to Enrollment

Brief Summary of Protocol:
A pure tone of sound consists of a single frequency. We can distinguish two pure sounds if their frequencies differ by 0.2% or even less. This separation is much less than a semitone—a step between adjacent piano keys—which represents about 6% in frequency. We wish to study how this frequency discrimination is achieved.

A sound is changed into electrical signals within the inner ear. The 30,000 fibers of the nerve that allows us to hear (auditory nerve) collects this information and sends it to the brain. In response to a sound, some nerve fibers are excited while the rest remain quiet. Which nerve fibers respond provides information about the sound.

When stimulated by a pure tone at a frequency below 300 Hz, a nerve fiber may produce an electrical signal—called an action potential—at every cycle of stimulation. The position within that cycle at which the action potential occurs is the same from cycle to cycle. This behavior can provide information to the brain about the frequency of the sound. When the frequency of the sound lies between 300 Hz and 4,000 Hz, a nerve fiber can no longer respond to every cycle. The responses still occur, however, at a preferred position within a cycle. This information may help us to distinguish between different frequencies.

In our research we wish to learn whether the phase information described above helps us to discriminate between tones of different frequencies. We will produce tones that have a certain frequency but in which the phase is altered. We will then perform experiments that measure our ability to discriminate such sounds.

Detailed Description of Protocol:
About 10 people will take part in the research study at the Rockefeller University. If you join the research study, you will take part from one two-hour session, and you may be invited to return for up to eight sessions. The research study as a whole will last about 2 years.

What specifically makes a person eligible for the study?
You may be eligible to enter this study:

- Have played a muscial instrument for more than 3 years OR
- Have been a trained singer for more than 3 years
- Fluent in English



Children permitted to participate:

Potential Benefits.....
This study will not benefit you directly. The information learned is meant to help us understand how people hear. In the long run, the work may assist researchers in improving hearing aids, cochlear implants, and other tools for communication.

Compensation is provided.