Forest Acoustic Ecology

An interactive experiment comparing human hearing (20 Hz - 20 kHz) with ultrasonic animal hearing (up to 300 kHz). Observe the difference between raw acoustic power and the vast bandwidth of high-frequency information.

Human Range Ultrasonic Range

Real-time Frequency Visualization

Animated representation of sound waves in the forest canopy. Humans hear the high-power, low-frequency rumbles (red). Animals hear the low-power, high-frequency ultrasonic chirps (blue).

The Power vs. Info Paradox

Sound Power: Low frequencies carry immense physical energy and travel great distances (wind, thunder, large animals). Humans are well-adapted to hear this raw power. Ultrasonic frequencies attenuate (fade) very quickly in the air.

Information: Bandwidth equals information capacity. The ultrasonic spectrum is vast. While humans hear ~20 kHz of bandwidth, a bat has access to over 150 kHz of bandwidth. This allows for incredibly fast, highly detailed, and complex communication and echolocation that we are completely deaf to.

Ambient Sound Power (dB SPL)

Estimated average acoustic energy in a forest environment.

Relative Information Capacity (Bandwidth)

Wider hearing ranges allow for processing vastly more ecological data per second.

Ray-Traced Acoustic Simulator: Direction & Reflection

Physics of Echolocation: Sound waves only reflect off objects larger than their wavelength. This ray-traced simulation models hundreds of acoustic paths, showing exactly how power scatters in different directions upon reflection, and how low frequencies diffract (pass through) small obstacles.

Experiment Designer: Target Sizing & Mathematical Acoustics

Because acoustic energy drops by extreme orders of magnitude via spherical spreading and Rayleigh scattering, we must use a Decibel (dB) scale to properly compare returning power. Target placed at 1.5 meters (3m round trip). Max possible reflection = 0 dB.

Raw Reflected Power (~4 kHz) -0 dB
0 dB -60 dB

Calculated via target surface area interception and Rayleigh scattering limits.

Perceived Ear Power (~4 kHz) -0 dB

Remaining energy integrated against human hearing sensitivity thresholds.

Human Audibility Verdict:
Select a size

Power Spectrum (Logarithmic dB)

Notice how high frequencies drop off heavily due to atmospheric attenuation ($0.0003 \times f^2$ dB/m). Low frequencies drop off on small targets due to Rayleigh scattering.

🔬 Advanced Spectrographic Analysis: Avoidance of Self-Deafening

This 3-panel spectrograph models absolute physical energy (-60 to 0 dB) and displays three temporal phases:
1. Source (t≈0) | 2. Received Echo (t≈10ms) | 3. Perceived Echo (t≈18ms): Filtered by the subject's brain (H(f)).
Observe the biological mastery: The Bat CW emits a tone at 74 kHz, but its brain is tuned to an 80 kHz "Acoustic Fovea". This decoupling prevents the loud emission from deafening the bat, relying on the Doppler-shift of flight to perfectly land the echo into the 80 kHz fovea! The Bat FM emits a 100-25 kHz sweep, but its brain ignores the heavily attenuated highest frequencies, peaking its sensitivity near 45 kHz.

0 ms (Source Emission) Time ➔ 28 ms