Field crickets solve the cocktail party problem through behavioural adjustments

by Rahul Kumar

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Imagine you are at a crowded wedding reception where many people are talking at the same time. There are loud noises all around and you are trying to listen to just one person, a situation designated by scientists as the “cocktail party problem.” To deal with this acoustic chaos, your brain ignores the background noise and focuses on one voice. Also, you start speaking louder, a response called as the Lombard effect, named after its discoverer, E. Lombard.

The field cricket, Acanthogryllus asiaticus, a field cricket from the Indian subcontinent, also encounters the same problem. In these insects, the multiple males generate long distance mating calls. Such simultaneous signalling evolved to evade detection by predators. But these group calls can also cause acoustic masking of individual calls, obscuring mate recognition by females and individual mating chances.

How does A. asiaticus deal with this problem?

To answer this question, Manjari Jain and Richa Singh from IISER, Mohali along with Jimmy Bahuleyan from Microsoft India Pvt. Ltd., Hyderabad, conducted a series of behavioural studies on A. asiaticus along with some simulations. Behavioural studies were conducted both in natural habitats and under laboratory conditions.

The scientists measured sound pressure level of the male calling behaviour in the field during their peak calling hours using acoustic instruments. Average sound pressure level was 62 decibels. Then, they measured the distance over which the calls of A. asiaticus males are audible. They broadcasted the simulated call of A. asiaticus at 62 decibels in field and measured the sound pressure levels at different distances. The call of A. asiaticus was audible up to 3 meters. Beyond 3 meters, the call and background noise become indistinguishable. These baseline measurements were the fundamental prerequisites for designing experiments to investigate the specific mechanisms A. asiaticus employs to deal with the cocktail party problem.

An individual can deal with the challenges of acoustic masking by conspecifics in three possible ways: by horizontal spacing, by changing its temporal call features, and by increasing its sound level, the Lombard effect. 

Does A. asiaticus utilize a single strategy, or a combination of all three?

To answer this question, scientists studied the spatial distribution of calling males and acoustic interactions among them in natural habitats during their peak calling hours. They also studied acoustic interactions under laboratory conditions. They played several rounds of species-specific simulated calls of 62 decibels to an A. asiaticus male. The simulated calls were paused briefly, and the sound pressure level of the male was recorded. They also calculated phase angles, recorded call patterns, and other characteristics of calls both from natural habitats and laboratory conditions. Phase angle calculations allowed the scientists to find synchrony and alternation among calls of different individuals. 

Analysis of spatial distribution revealed that there is only a 17% chance that a calling male will face acoustic masking interference from others. It shows the existence of horizontal spacing between calling males of A. asiaticus, which allows a calling male to avoid acoustic masking from others. Acoustic interaction data and calculation of phase angle suggests change in temporal call features of the focal male, the male under focus or study, when exposed to calls of other individuals. The change included the focal male alternating chirps with the audible maskers. Also, an increase in chirp rate was observed in the presence of an acoustic masker. 

To test the Lombard effect, they conducted a playback experiment where a recorded call of a solo-calling individual was played five decibels higher and five decibels lower than the normal sound pressure level in front of an A. asiaticus male for two minutes, with a break of two minutes between them. The sound pressure level of the A. asiaticus male was recorded immediately after the playback stopped. The same experiment was repeated after two minutes. This experiment disproves the existence of the Lombard effect in A. asiaticus males against acoustic masking. It was found that, rather than simply increasing its sound pressure level, an A. asiaticus male can either decrease or increase it depending on the intensity of the stimulus as well as the number of times the stimulus is presented. A steep increase in the sound pressure level is not evolutionarily favourable. Rather, a decrease in sound pressure level helps to avoid detection by predators, reduces competition, and conserves energy.

Therefore, through behavioural adjustments including the separation of activities across space and time, and the sound pressure level modulations, A. asiaticus efficiently solves the cocktail party problem under conditions where separation of acoustic signals is difficult to achieve.

For more details, please refer:

Richa Singh, Jimmy Bahuleyan and Manjari Jain (2026). A field cricket's solutions to the cocktail party problem in conspecific choruses. Behavioral Ecology, Volume 37, Issue 1, araf143. https://doi.org/10.1093/beheco/araf143

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About the author:

Dr Rahul Kumar is one of the associate editors of “Indian Entomologist.” He is currently working as an Assistant Professor and Head of the Department of Zoology at Sheodeni Sao College (Magadh University), Kaler-824127, India. His ongoing research primarily addresses the behavioural, evolutionary, and taxonomic aspects of insects and spiders. Additionally, he has worked on molecular biology (eukaryotic gene regulation) at JNU, New Delhi; nanotechnology (nano-therapeutics and diagnostics) at AIIMS, New Delhi; science education (activity-based teaching-learning) at NCERT, New Delhi and insect taxonomy (micro-moths) at ICAR-IARI, New Delhi as a research fellow.

Email: rahuldayanand33@gmail.com

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