Refers to the purity of a sound and is influenced by the timing, amplitude, and frequency of the sound waves combined. For example, the timbre of a sound is what makes different musical instruments playing the same note and loudness sound distinct.

Timbre

The anatomy of the human auditory system comprises several anatomical structures that capture sound waves and transmit them inward. Sound waves initially enter the auditory canal. The visible external ear includes the pinna, which leads to the tympanic membrane (eardrum). Beyond this are the ossicles, which consist of the malleus, incus, and stapes. Further inward, a close-up of the inner ear reveals additional structures, including the semicircular canals, utricle, saccule, oval window, cochlea, basilar membrane, and hair cells.

Anatomy of the Auditory System

People can discriminate changes in frequency between two tones by about 2 Hz for sounds up to 2000 Hz. Pitch relies on the subjective expereince of sound, which means frequency of sound is not the only determinant of pitch. There are two complementary ways that pitch information is encoded.

Encoding pitch information

Auditory signals are able to integrate information from both ears in order to identify the sourse of a sound. This helps with allerting danger, potential mates, or other situational information that is necessary for survival and normal activities throughout the day. Humans have an accuracy of about 1 degree horizontally around their head, and may animals demonstrate even higher accuracy. There are two types of binaural (two-ear)cues that help with localization on the horizontal plane; intensity and latency.

Auditory systems for localizing sound

Sound transduction is the continuous process where sound waves funneled into the auditory canal cause eardrum vibrations that move the ossicles. The stapes then presses the cochlea's oval window, moving fluid that enlarges hair cells on the basilar membrane, which ultimately send neural impulses to the brain via the auditory nerve.

Sound Transduction in the Ear

Based on the fundamental principle that hearing involves converting pressure waves from the environment into sound, explain why the person's hearing was temporarily affected and what happened when they yawned.

Explaining an Everyday Auditory Phenomenon

A musician plays a note on a guitar. They then tighten a string and pluck it more gently, producing a second note that is perceived as higher in pitch and quieter. What physical changes in the sound waves correspond to this perceptual change?

Sound localization is the auditory ability to identify the origin of a sound within an environment, which is a crucial aspect of hearing. This ability is analogous to depth perception in the visual system. Just as depth perception relies on monocular and binocular visual cues, the auditory system utilizes both monaural (one-eared) and binaural (two-eared) cues to pinpoint where a sound is coming from.

Sound Localization

Audition, or hearing, is the process by which the auditory system converts pressure waves from the environment into meaningful sounds. This capability is fundamental for human experience, enabling communication through spoken language, the appreciation of music, and the perception of environmental sounds.

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The common idea that humans have only five senses is oversimplified. Along with vision, hearing or audition, smell or olfaction, taste or gustation, and touch or somatosensation, humans also have sensory systems for balance, body position and movement, pain, and temperature.

The Senses

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

People tend to use a high amount of visual information to inform their daily activities. There is also a lot of sensory information coming in through the eyes, which makes the visual system a highly researched field of neuroscience. 

Vision

The vestibular sense is the sensory system responsible for maintaining balance and body posture. It operates through the response of specialized hair cells located in the utricle, saccule, and semi-circular canals of the inner ear, which detect changes in head position and gravity.

Vestibular Sense

Gustation (also known as "taste") is a chemical sense that allows individuals to sense and perceive five major flavors: sweet, salty, sour, bitter, and umami.

Gustation (Taste)

Audition (Hearing)

Proprioception is the sensory perception of the position of the body's parts. This sense allows an individual to understand their body's orientation in space without relying on visual cues.

Proprioception

Kinesthesia refers to the perception of the movement of the body through space.

Kinesthesia

Nociception is the sensory system that provides the brain with information related to pain, typically in response to potentially damaging stimuli.

Nociception (Pain)

Somatosensation, commonly known as the sense of touch, is the sensory system responsible for perceiving contact with the skin.

Touch (Somatosensation)

The sensory modalities of taste (gustation) and smell (olfaction) are classified as chemical senses. This categorization is due to the fact that they rely on specialized sensory receptors designed to detect and respond to specific molecules present in the food consumed and the air inhaled.

Chemical Senses

Thermoception is the sensory system that enables an organism to perceive temperature. This process relies on specialized sensory receptors, known as thermoreceptors, which are primarily located in the skin and detect changes in temperature from the external environment.

Thermoception (Temperature)

The body senses are a group of sensory modalities that provide information about the body itself and its interaction with the environment. This category includes touch (somatosensation), temperature perception (thermoception), pain (nociception), balance (vestibular sense), and the sense of body position and movement (proprioception and kinesthesia).

Body Senses

Analyze the following scenario and explain the roles of three key sensory systems (other than vision) that are critical for the individual's performance.

Sensory Integration in Action

Nociception is a sensory system that provides information about pain.

Nociception

The senses function as the interface between the mind and the external environment. They receive environmental stimuli and translate them into nervous impulses, which are then transmitted to the brain for processing.

Sensory Interface with the External Environment

Thermoception is a sensory system that provides information about temperature.

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