If you have ever had trouble understanding what a person was saying to you in a noisy
group setting, then you have experienced a condition known as “the cocktail-party problem.”
The cocktail party problem is a condition in which an individual has trouble hearing and
understanding an isolated target signal in a noisy group setting. When natural increases and
decreases in the levels of background noise occur, a phenomenon known as “modulation
masking release” may allow the listener to decipher the target signal during the times when
background noise is lowest.
Frogs breed in noisy groups known as choruses. Within these choruses, females must
isolate the most attractive male call possible from the cacophony around them—thus, they
are also subject to the cocktail party problem. Using simulated mating calls and modulated
chorus noise, my colleagues and I attempted to study how grey tree frogs may use masking
release to resolve the cocktail party problem within mating groups.
I hypothesized that exposure to low-frequency modulated chorus-like noise would allow
frogs to experience modulation masking release, resulting in an overall improved phonotaxis
(sound response) compared to unmodulated (constant) levels of background noise.
Additionally, I expected the effect of masking release to be more prominent when the mating
call was longest. However, experimental results revealed that the presence of modulated
chorus noise confers no significant benefit to females when they are isolating and choosing
male calls with respect to flat, unmodulated noise. Future successful studies such as this
one could ultimately benefit the hearing-impaired by helping audiologists to create better
Additional contributors: Alejandro Vélez; Sandra Tekmen; Mark Bee (faculty mentor)
This research was supported by the Undergraduate Research Opportunities Program (UROP).
Solving the “Cocktail Party Problem:” Fluctuating Background Noise Effects on Signal Recognition in Cope’s Grey Tree Frog.
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