4.2 Distortion of patterns and masking by noise

What is the role of transfer functions in sound frequency distortion?

how sound frequencies change due to environmental factors

Distortion of frequency pattern factors

heat loss, scattering, boundary effects

Heat loss

loss of energy with distance

Scattering

filtering of high frequencies (differences in impedance)

Boundary effects

Between two senders and receivers and two media with different impedance

Main issue of sender and receiver height on boundary interference

Out of phase waves causing interference

- angles

Distortion of temporal pattern

Reverberation, modulation, dispersion

Reverberations (echoes) where is it high

In forested areas

Modulation what adds heterogeneity

turbulences and eddies add heterogeneity to medium

Modulation what adds amplitude modulation

currents and wind

What contributes to more distortions in modulation

distance and high frequencies

Dispersion

different frequencies propagate at different times > temporal and spatial dispersion > speed and waveform changes

What does noise do in active space

set the limits of active space size

What will noise affect

detection

discrimination

identification

scaling

localization

Signal detection theory shows us what

receiver's accuracy, decision, bias or criterion, noise or competition between stimuli

Liberal vs conservative

Liberal: more likely to indicate yes when idk

Conservative: more likely to indicate no when idk

What is the concept of 'signal-to-noise ratio'?

Signal-to-noise ratio refers to the comparison between the level of a desired signal and the level of background noise.

Noise or competition between stimuli factors

Amplitude, frequency, spatial distribution, temporal pattern

Factors in noise masking

High amplitude signals/stimuli

Contrast in frequency between noise and signal/stimulus

Continuity

directionality

distance

topography

High amplitude signals/stimuli

yellings vs whisper

Contrast in frequency between noise and signal/stimulus

AC vs voice

Continuity

Continuous noises may be harder to detect

Directionality

of sensory-auditory organs

Background noise examples

Wind, moving water, rain, vehicular traffic (bus), sound-making animals

What kind of animals tend to use continuous sounds

Insects and amphibians

What kind of animals tend to use discreet, intermittent sounds and take advantage of the "quiet" band

birds and mammals

How do small and large animals differ in sound frequency trends?

Smaller animals tend to produce higher frequencies, while larger animals produce lower frequencies.

What does body size and sound apply to

species, individuals, age, sex (in sexually dimorphic)