4) Audition I

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Questions and Answers

What does the amplitude of a sound wave primarily relate to?

Sound duration

The type of sound

Frequency of sound

Perception of loudness (correct)

Which structure in the ear is responsible for amplifying vibrations from the tympanic membrane?

Pinnae

Ossicles (correct)

Cochlea

Auditory canal

What is the relationship between frequency and perception of pitch?

Higher frequencies produce stronger amplitudes

Higher frequencies produce lower pitches

Lower frequencies produce lower pitches (correct)

Frequency has no effect on pitch perception

What initiates auditory transduction in the inner ear?

Motion of the basilar membrane Signup and view all the answers

What defines sound in a physical sense?

Vibrations of an object creating pressure changes Signup and view all the answers

Which part of the ear is responsible for protecting the middle ear?

Auditory canal Signup and view all the answers

What is a fundamental frequency in complex sounds?

The basic pitch of a sound Signup and view all the answers

How does the ear perceive loudness when sound wave amplitudes vary?

Loudness perception increases with larger amplitudes Signup and view all the answers

What role do hair cells in the organ of Corti play in the auditory process?

They produce impulses sent to the brain Signup and view all the answers

What can lead to hearing loss regarding the hair cells in the auditory system?

Overstimulation by excessively loud sounds Signup and view all the answers

What primarily determines the perceived pitch of a sound?

The fundamental frequency of the sound Signup and view all the answers

What is the phenomenon called when a pitch is perceived even in the absence of its fundamental frequency?

Missing fundamental illusion Signup and view all the answers

Which structure of the auditory system is responsible for amplifying vibrations?

Ossicles Signup and view all the answers

How is loudness perception related to sound waves?

It correlates with the amplitude of sound waves Signup and view all the answers

What type of sounds are made up of multiple waveforms with different frequencies?

Complex sounds Signup and view all the answers

At what range of frequencies does the auditory nerve respond phase-locked to pressure changes?

Up to 4000 Hz Signup and view all the answers

What mechanism allows the auditory system to encode different frequencies of sound?

Timing code and place code Signup and view all the answers

What role do hair cells in the organ of Corti play in the auditory system?

They convert vibrations into electrical signals Signup and view all the answers

Which part of the ear is responsible for funneling sound into the ear canal?

Pinnae Signup and view all the answers

Why might sounds of the same amplitude differ in perceived loudness?

Because of frequency variations Signup and view all the answers

What is the relationship between amplitude and loudness in sound perception?

An increase in amplitude by a factor of approximately 3.16 is needed for perceived doubling of loudness. Signup and view all the answers

How are sound levels measured?

On a logarithmic scale in units called decibels. Signup and view all the answers

Which of the following statements about pitch is true?

The basilar membrane responds to specific frequencies along its length. Signup and view all the answers

What does the timing code refer to in auditory perception?

The synchronization of auditory nerve responses to frequency. Signup and view all the answers

What is indicated by a change of 20 dB on the decibel scale?

A ten-fold increase in amplitude. Signup and view all the answers

Which of the following factors does NOT influence loudness perception?

Duration of the sound. Signup and view all the answers

What is phase-locking in the context of hearing?

The synchronization of auditory nerve fiber firing with sound waves. Signup and view all the answers

At what frequency range is phase-locking most effective?

Up to about 4000 Hz. Signup and view all the answers

Where along the basilar membrane do low frequencies primarily activate hair cells?

Near the apex. Signup and view all the answers

Which of the following best describes the sensitivity of the human auditory system to different frequencies?

Sensitivity is poorer for both very low and very high frequencies. Signup and view all the answers

Study Notes

Cognitive Psychology 1 - Audition I: Loudness and Pitch

Learning Objectives:
- Describe the stimulus for hearing
- Outline the basic structure and operation of the human auditory system
- Describe perception of loudness and pitch, relating them to auditory input and how this input is coded by the auditory system

The Sound Stimulus

What is sound?
- Perceptual definition: Sound is the experience we have when we hear.
- Physical definition: Sound is pressure changes in the air (or other medium) caused by the vibration of an object.
  - A pure tone results when changes in air pressure create a perfect sine wave.

Characteristics of Sound - Pure Tones

Amplitude:
- The size of the variation in air pressure (difference between peak and trough).
- Correlates with perceived loudness.
Frequency:
- Number of cycles per second (measured in Hertz).
- Correlates with perceived pitch.

Characteristics of Sound - Complex Sounds

Most sounds are more complex than pure tones.
Sounds are combinations of sine waves.
Natural sounds often consist of a fundamental frequency with additional higher frequency waveforms (harmonics).

Overview of the Ear

The human ear is divided into three parts: outer, middle, and inner.

Outer Ear

Pinna: The visible external part of the ear.
Auditory canal: A ~3cm tube-like structure that protects the middle ear.
Tympanic membrane (eardrum): A cone-shaped membrane separating the outer and middle ear; vibrates in response to sound waves.

Middle Ear

The middle ear is a small cavity containing the ossicles (malleus, incus, stapes).
The ossicles amplify vibrations from the tympanic membrane and transmit them to the inner ear via the oval window.

Inner Ear

The inner ear's main structure is the cochlea, a snail-like, liquid-filled organ.
Vibration of the oval window displaces fluid in the cochlea, resulting in changes in pressure that propagate through the cochlea's spiral structure.
The cochlea consists of three parallel canals (vestibular, middle, and tympanic).
Auditory transduction is triggered by the motion of the basilar membrane, which separates the middle and tympanic canals.

Auditory Transduction

Motion of the basilar membrane translates into neural signals via specialized hair cells in the organ of Corti.
A voltage is generated when these hair cells are bent.
This produces impulses in auditory nerve cells sent to the brain.
Hair cells are extremely sensitive.
Overstimulation (loud sounds) can damage hair cells, leading to hearing loss.

Loudness

Perception of loudness relates to sound wave amplitude.
Sound levels are measured on a logarithmic scale in decibels (dB).
A change of 20dB corresponds to a ten-fold increase in amplitude.
Loudness is coded (encoded) by the firing rate of auditory nerve fibers (rate code).
Higher amplitude sounds lead to faster firing rates of auditory nerve fibers.
Loudness perception is not directly proportional to amplitude, it requires a relatively greater change in sound amplitude for equal increases in the amount of perceived loudness.

Pitch

Humans are sensitive to a wide range of sound frequencies (20 Hz to 20,000 Hz).
Place code: Sound frequencies cause vibration in specific areas along the basilar membrane.
- Low frequencies vibrate near the apex.
- High frequencies vibrate near the base.
Timing code: Auditory nerve responses are synchronized to pressure changes in sounds up to ~4000 Hz (phase-locking).
Pitch perception is typically determined by the fundamental frequency of the sound but also affected by harmonics and other phenomena like the missing fundamental illusion.

Summary

Sound: Pressure changes in a medium (typically air), caused by the vibration of objects.
Pure Tones: Sine-wave pressure changes characterized by amplitude, frequency.
Complex Tones: Contain various frequencies and are often composed of a fundamental frequency and harmonics (with different amplitude relationships).
Loudness: Related to sound wave amplitude; measured in decibels; coded by the rate of auditory nerve firing.
Pitch: Determined by sound frequency; coded in two ways: place code along the basilar membrane and timing code within the auditory nerve (synchronization to pressure changes).

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Description

This quiz explores the fundamentals of audition, focusing on the perception of loudness and pitch. It covers the structure of the human auditory system and how sound stimuli are processed. Ideal for students studying cognitive psychology.