What is sound caused by?
changes in air pressure
What are the three pressure waves characterised by?
Amplitude - loudness
Frequency - pitch
Phase - position in a cycle
What is the simplest sound wave?
A pure tone (sine wave)
What is the human hearing range
20 - 200000 Hz
What is the typical vocal range?
80-1100HZ
What are Sine Waves?
A sine wave represents a pure tone — a sound with only one frequency (e.g., a tuning fork).
What are complex sounds?
Complex sounds are many sine waves together, all with differing amplitude, frequency and phase
What is the fundemantal
The lowest frequency component of a complex sound
What are harmonics
These are additional frequencies that appear naturally when something vibrates.
They’re integer multiples of the fundamental (the lowest component of a complex sound) — meaning they’re exactly 2×, 3×, 4×, etc. the base frequency.
Each harmonic adds richness to the sound.
In sound what happens if the harmonics is not a perfect multiple of the fundamental?
your ear treats them as separate tones or noise, not part of one clean sound.
What components are in the outer ear
Pinna
External auditory canal
Eardrum
What is the Pinna (outer ear)
- increases the sound amplitutde
- helps determine the direction in which the sound is coming
What is the external auditory canal? (outer ear)
- provides protection
- increases the sound amplitude
What is the eardrum? (outer ear)
- vibrates in response to sound
- moves bones in the middle ear
Whats in the middle ear?
- This eardrum is connected to three tiny bones called Ossicles
- These bones transmit the vibration of the eardrum into the choclea
- They also protect high-altitude sounds
- these are the smallest bones in the human body
Three types of Ossicles (middle ear)
Malleus
Incus
Stapes
What does the inner ear consist of?
- Choclea
- semicircular canals
What do semi-circular canals do? (inner ear)
- provide sense of orientation
What is the Choclea (inner ear)
A spiral-shaped structure deep in the inner ear that turns sound vibrations into nerve signals that the brain understands as sound
Process of sound through the Choclea
- The stapes (smallest ossicles) is attached directly to the Cochlea membrane’s oval window (this is where vibrations get into the choclea)
- The oval window is smaller than the eardrum, so helps amplify the sound
- -
What are the three canals in the Choclea?
- Vestibular Canal
- Tympanic canal
- Choclea Duct
*vibrate in response to oval window
The three Choclea canals (vestibular, tympanic and choclear duct) are separated by what?
- Reisnner membrane
- Baisler membrane (hair cells)
When the basisler membrane vibrates, what does this do?
hair cells are set in motion - converts the vibrations into neural signals
When sound waves enter your ear they are transformed into electrical signals by the Choclea. These electrical signals (which represent different sounds) travel along nerve fibres to the brain. However, the pathway from the choclea to the primary auditory cortex goes through this path:
(how does the path of sound look from the cochlear nerve to the primary auditory cortext)
- the choclear nucleus
- the superior oliviary nucleus
- The inferior nucleus
- The medial genicuate nucleus
The signal arriving at the cochlear nucleus splits and goes to each of the superior olivary nuclei
