Species shift calls to ultrasonic frequencies to escape constant noise masking

Evidence

In soundscape ecology noise is not simply an unwanted sound but a sound that reduces, by masking, the quality of every other acoustic signal. … To reduce the masking effect of background noise, some species have modified their vocalizations, shifting the vocalizations to ultrasonic frequency bands. It is the case of the concaveeared torrent frog (Amolops tormotus), a species of arboreal frog of Central China that has ultrasonic harmonics used to communicate in a noisy environment … Ultrasonic components have been found also in the song of the black-faced warbler (Abroscopus albogularis), an oscine songbird that lives close to the torrents in a constant noisy environment (Narins et al. — Almo Farina, Soundscape Ecology, 1288

Categorization

• XREF: Extends the masking-reaction claims: frequency shift, amplitude shift, and repetition are the three noise responses. — connects to: Noise masks at least one of the three sound-source types — Almo Farina, Soundscape Ecology: Principles,…, 1234; Lombard effect describes raising vocal intensity when background noise is loud — Almo Farina, Soundscape Ecology: Principles,…, 1296; Birds either shift song frequency up or abandon noisy areas to escape traffic masking — Almo Farina, Soundscape Ecology: Principles,…, 1366 (+17 more)

Broader Connections

• Masking acts within critical bandwidths, leaving distant-frequency sounds unaffected #qualifies (0.80) — Eric J. Heller, Why You Hear What You Hear- An…, 2009
• Organisms adapt to natural noise but suffer stress from anthropogenic noise #expands (0.78) — Almo Farina, Soundscape Ecology, 1275
• Habitat structure drives the evolution of animal vocal signals #expands (0.75) — Almo Farina, Soundscape Ecology, 494
• Ambient noise impairs birds’ territory defense and mate attraction #expands (0.72) — Gordon Hempton, John Grossmann, One Square Inch of Silence- One Man’s…, 942