Part B · Wave boundaries, echoes and hearing Waves mind map

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Part B · Wave boundaries, echoes and hearing Waves mind map

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Boundaries

Interactions: Reflection, transmission, refraction and absorption may coexist
Frequency: Source sets f; crossing boundary changes v / λ, not f
Echo · Higher: One-way distance = speed × round-trip time ÷ 2

Applications · Higher

Frequency bands: Ultrasound >20,000 Hz; infrasound <20 Hz
Ultrasound: Tissue reflections → fetal image; sonar; non-ionising sound
Infrasound / seismic: Long-distance monitoring; boundaries reveal Earth’s structure

Hearing · Higher

Signal path: Eardrum → ossicles → cochlea → auditory nerve
Human range: Young healthy ear ≈20–20,000 Hz; age / damage reduce it
Transducers: Microphone / speaker diaphragms have limited frequency response
Protect / distinguish: Limit loud exposure; pitch relates to f, loudness to intensity

Connections

Boundaries → Applications · Higher: Reflections and travel times enable imaging and sonar.
Applications · Higher → Hearing · Higher: Sound frequency determines applications and the limits of hearing.