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3.2Chapter 3: Sound

Detecting sounds — Alhussan Physics - Stage 7 Revision Notes & Topical Questions

5 min read 7 parts Lesson 2 of 4 1 quiz

📚 Alhussan Physics - Stage 7 Hub / Topical Revision
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Lesson summary

3.2 Detecting sounds — The Human Ear and Microphones — Alhussan International Academy — Physics (Stages 7–9) notes: Describe how the ear detects sound, how hearing can be damaged, and how microphones and loudspeakers work as transducers.Detectors — the ear and a microphone both d…

  • Membranes and bones
  • Specialised cells
  • Delicate structures
  • Loud sounds
  • Pressure changes
  • Ear infection

Part 1 of 5Detecting sounds

Detectors
  • Detectors the ear and a microphone both detect sounds.
Two ears
  • Two ears they help you work out where a sound comes from, because sounds reach the ears at slightly different times.
Pinna
  • Pinna the part of the ear you can see in a mirror.

Part 2 of 5How the ear works

1
The outer ear gathers the sound wave and directs it down the auditory canal to the eardrum.
2
The wave makes the eardrum vibrate, and this makes the ossicles vibrate.
3
The ossicles pass the vibration to the oval window and then to the inner ear.
4
The oval window transmits the vibration to the fluid in the cochlea.
5
The vibrating fluid makes hairs in the cochlea vibrate.
6
The hairs are connected to sound-detecting cells, which release chemicals that produce a signal.
7
The signal travels down the auditory nerve to the brain, which processes it, and you hear the sound.
Ossicles
  • Ossicles the three smallest bones in the body, which make up the middle ear.
Inner ear
  • Inner ear it is made of the semicircular canals and the cochlea.
  • The semicircular canals help you to balance.
  • The cochlea is curled like a snail shell and contains fluid.
Membranes and bones
  • Membranes and bones the membranes and bones of the middle ear transfer the vibration from the outer to the inner ear.
Specialised cells
  • Specialised cells sound-detecting cells are examples of specialised cells studied in biology.

Part 3 of 5Hearing loss

Hearing loss
Delicate structures
  • Delicate structures the ear contains the tiny ossicle bones and the thin membranes of the oval window and eardrum,
    • which can be damaged in several ways.
Loud sounds
  • Loud sounds they can destroy the sound-detecting cells in the cochlea, causing permanent hearing loss.
  • Loud music at concerts can damage hearing.
Pressure changes
  • Pressure changes they can perforate (make a hole in) the eardrum, which usually heals in a few weeks or months.
Ear wax
  • Ear wax ears make wax naturally to clean themselves, but too much can affect hearing, and excess wax is easy to remove.
Ear infection
  • Ear infection fluid can be produced around the small bones, which interferes with transfer of the sound wave from the outer ear to the inner ear.
Head injuries
  • Head injuries they can damage the auditory nerve and affect the ability to hear.
Sharp objects
  • Sharp objects putting them in the ear is dangerous because they can damage the eardrum.
Age
  • Age older people do not hear high-pitched sounds as well as younger people, and some people wear hearing aids.

Part 4 of 5Microphones

Transducer
Transducer a device that converts energy from one form to another.
Microphone
  • Microphone a type of transducer that converts a sound wave into an electrical signal, and the ear is the body's microphone.
Diaphragm
  • Diaphragm a flexible plate in a microphone that moves backwards and forwards with the sound wave, like an eardrum.
Signal
  • Signal the movement produces an electrical signal that can be amplified and sent to a loudspeaker or recorded.
Similarity with the ear
  • Similarity with the ear both detect sound and produce an electrical signal.

Part 5 of 5Loudspeakers

Loudspeaker
  • Loudspeaker another type of transducer, which converts an electrical signal into a sound wave.
Action
  • Action the electrical signal makes the cone vibrate, so the air particles move backwards and forwards to make a sound wave.
Reverse of a microphone
  • Reverse of a microphone a microphone is a bit like a loudspeaker in reverse.
DeviceInputOutput
MicrophoneSound waveElectrical signal
LoudspeakerElectrical signalSound wave

Key terms

TermMeaning
Pinnathe visible part of the outer ear that gathers sound.
Eardruma thin membrane that vibrates when sound waves reach it.
Ossiclesthree tiny bones that pass vibrations from the eardrum to the oval window.
Cochleathe fluid-filled part of the inner ear containing the sound-detecting cells.
Transducera device that converts energy from one form to another.
Diaphragma flexible plate in a microphone that moves with a sound wave.

Avoid these mistakes

1
Thinking the pinna is the whole ear — it is only the part you can see, and most of the ear is inside the head.
2
Saying the cochlea collects sound — the pinna and canal collect it, and the cochlea changes vibrations into nerve signals.
3
Thinking a perforated eardrum is permanent — it usually heals in weeks or months.
4
Mixing up what a microphone and a loudspeaker do — a microphone makes an electrical signal and a loudspeaker makes sound.

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