Podcast
Questions and Answers
What do sound waves result from?
What do sound waves result from?
How do sound waves travel through media at different speeds?
How do sound waves travel through media at different speeds?
Which psychological aspect of sound is mainly related to the perceived frequency?
Which psychological aspect of sound is mainly related to the perceived frequency?
What is the physical quality of sound waves that is associated with loudness?
What is the physical quality of sound waves that is associated with loudness?
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How are differences in amplitude described when measuring sound pressure levels?
How are differences in amplitude described when measuring sound pressure levels?
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What is the term used to describe combinations of sine waves that create complex sounds?
What is the term used to describe combinations of sine waves that create complex sounds?
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Which part of the human ear protects the eardrum from damage and amplifies sounds in the 2000-6000 Hz range?
Which part of the human ear protects the eardrum from damage and amplifies sounds in the 2000-6000 Hz range?
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What is the main structure in the inner ear where transduction of pressure changes into neural signals occurs?
What is the main structure in the inner ear where transduction of pressure changes into neural signals occurs?
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Which ossicle in the middle ear receives vibrations from the tympanic membrane and is attached to the incus?
Which ossicle in the middle ear receives vibrations from the tympanic membrane and is attached to the incus?
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What term is used to describe the lowest harmonic frequency in a sound produced by a vibrating object?
What term is used to describe the lowest harmonic frequency in a sound produced by a vibrating object?
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Study Notes
Hearing: Physiology and Psychoacoustics
- Hearing is secondary to vision, but it plays a crucial role in our daily lives, and its absence would make life more difficult to navigate.
- Sound is created when objects vibrate, causing molecules to vibrate and resulting in waves of pressure changes in the medium.
Physical Quality of Sound Waves
- Sound waves have two main qualities: amplitude (intensity) and frequency.
- Amplitude (dB) measures the difference between the highest and lowest pressure in the wave.
- Frequency (Hz) measures the number of times per second that a pattern of pressure change repeats.
- Sound waves travel at different speeds through media: 340 m/s through air and 1500 m/s through water.
- Light waves travel approximately 1 million times faster than sound waves.
Qualities of Sound
- Loudness: the psychological aspect of sound related to perceived amplitude (or intensity).
- Pitch: the psychological aspect of sound related mainly to the perceived frequency.
- Timbre: the quality of the sound.
- Frequency is associated with pitch: low-frequency sounds correspond to low pitches, and high-frequency sounds correspond to high pitches.
- Amplitude is associated with loudness: high-amplitude sounds are louder, and low-amplitude sounds are quieter.
Measuring Sound Pressure Levels
- Sound levels are measured on a logarithmic scale, in decibels (dB).
- Relatively small decibel changes correspond to large physical and perceptual changes.
Sine Waves and Complex Sounds
- Sine waves dictate how they sound to us: a single sine wave results in a pure tone.
- Complex sounds (speech, instruments, environmental noise) are made up of combinations of sine waves.
- Complex sounds have a spectrum of amplitudes present at multiple frequencies.
- Complex sounds have harmonic spectra: one vibrating object will emit a spectrum of frequencies.
Physiology of the Human Ear
- The pinna funnels sound into the ear via the ear canal.
- Only mammals have pinnae (external ear structures).
- The side and shape of pinnae vary greatly between species.
Physiology of the Human Ear: Outer Ear
- The outer ear amplifies sounds in the 2000-6000 Hz range and protects the eardrum from damage.
- The pinna and ear canal make up the outer ear.
Physiology of the Human Ear: Middle Ear
- The tympanic membrane (eardrum) is a thin sheet of skin that moves in and out in response to sound pressure changes.
- The middle ear contains three ossicles (small bones) that amplify sound and transmit it to the inner ear.
- The three ossicles are: malleus, incus, and stapes.
Physiology of the Human Ear: Inner Ear
- The inner ear is where transduction of pressure changes into neural signals happens.
- The main structure of the inner ear is the cochlea.
- Activity in the cochlea is sent to the auditory nerve, then transmits info to auditory processing.
Physiology of the Human Ear: The Cochlea
- Vibrations in the middle ear push and pull the oval window from the vestibular canal.
- Pressure changes (traveling waves) flow in the fluid of the vestibular canal.
- Because the cochlea is closed, pressure can build up, and is then relieved via the round window.
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Description
Test your knowledge on the physiology and psychoacoustics of hearing. Learn about the importance of audition in our perception and how sound is created through the vibration of objects and molecules.
