Psych 3320 1st EditionExam # 4 Study Guide Chapters: 11-13Chapter 11-131. Describe the physical stimulus for sound, including the concepts of sound waves, pure tones, amplitude, and frequency. a. Physical stimulus=sound has frequency of 1,000 Hz. Also referred to as “sound.” b. Sound=refers to physical stimulus or perceptual response. Sound is pressure changes in theair or other medium. c. Perceptual definition=sound is the experience we have when we hear. d. Sound waves=pattern of pressure changes in a medium. Most of the sounds we hear are due to pressure changes in the air, although sound can be transmitted through water & solids as well. e. Pure tone=a tone w/pressure changes that can be described by a single sine wave.f. Amplitude=in the case of a repeating sound wave, such as the sine wave of a pure tone, amplitude represents the pressure diff. bwn. Atmospheric pressure & maximum pressure of the wave.g. Frequency=the # of times per second that pressure changes of a sound stimulus repeat. Frequency is measured in Hertz, where 1 Hertz is one cycle per second.2. Discuss how physical characteristics of the sound wave are related to the perceptual dimensions of loudness and pitch.a. Loudness=perceptual quality most closely related to the level or amplitude of an auditory stimulus, that is expressed in decibels. b. Pitch=perceptual quality we describe as “high” or “low,” can be defined as the property of auditory sensation in terms of which sounds may be ordered on a musical scale.c. Decibels associated w/loudness. d. Thresholds & loudness depend not only on decibels but also on frequency.--3. Explain what an audibility curve is and how these curves are different for different species. a. Audibility curve=a curve that indicates the sound pressure level (SPL) at threshold for frequencies across the audible spectrum. b. Humans can hear frequencies btwn 20 Hz & 20,000 Hz, other animals can hear frequenciesoutside the range of human hearing. Dogs can hear frequencies above 40,000 Hz, cats can hear about 50,000 Hz & elephants can hear stimuli below 20 Hz.4. Define timbre and discuss how perception of timbre is related to perception of complex sounds. a. Timbre=the quality that distinguishes btwn 2 tones that have the same loudness, pitch, & duration, but still sound different. b. Timbre depends on differences in harmonics of diff instruments & depends on the time course of a tone’s attack & decay. Difficult to distinguish btwn same instruments when tone’s attack & decay eliminated by erasing the first & last ½ second of the recording. c. Diff to distinguish one instrument from another is to play an instrument’s tone backward. d. Sounds produced by periodic & aperiodic sound events (have sound waves that do not repeat) more complex than musical tones, but all of these sound stimuli can be analyzed into a # of simpler frequency components. e.5. Be able to label the major ear structures: pinna, auditory canal, tympanic membrane, malleus, incus,stapes, eustachian tube, oval window, round window, semicircular canals, cochlea, auditory nerve).6. Identify the structures of the outer ear, middle ear, and inner ear. Discuss the functions of the outer, middle, and inner ear.a. Outer Ear=consists of the pinna & auditory canal.i. Pinnae=the structures that stick out from the side of the head. Most obvious part of the ear is important in helping us determine location of sounds and is of great importance for those who wear eyeglasses, it is part of the ear we could most easily do without.ii. Auditory canal=tubelike structure, about 3cm long in adults that protects the delicate structures of the middle ear from the hazards of the outside world. Auditory canal’s 3cm recess, along w/its wax, protects the delicate tympanic membrane. iii. Tempanic membrane (eardrum)=at the end of the canal & helps keep this membrane & the structures in the middle ear at a relatively constant temperature.iv. Resonance=occurs in auditory canal when sound waves that are reflected back from the closed end of the auditory canal interact w/sound waves that are entering the canal. b. Middle Ear=small cavity, about 2 cubic cm in volume, that separates the outer & inner ears. i. Ossicles=3 smallest bones in the human body. ii. Malleus=1st bone of the ossicles. (also known as the hammer) is set into vibration by the tympanic membrane to which it is attached, & transmits its vibrations to the Incus. iii. Incus=(also called anvil) which transmits malleus’ vibrations to the stapes (stirrup).iv. Stapes=(also called stirrups) Stapes transmits its vibrations to inner ear by pushingon the membrane covering the oval window. v. Middle ear muscles=smallest skeletal muscles in the human body. Attached to the ossicles, & at very high sound levels they contract to dampen the ossicles’ vibration. Reduces the transmission of low frequency sounds & helps to prevent intense low freq. components from interfering w/our perception of high frequencies. c. Inner Ear=main structure of the ear. i. Cochlea=liquid filled, snail-like structure. ii. Cochlear partition=upper half of the uncoiled cochlea, called the scala vestibuli & the lower half called the scala tympani, are separated by structure called cochlear partition. Extends almost entire length of cochlea, from its base near the stapes to its apex at the far end. iii. Organ of Corti=contains hair cells (receptors for hearing). iv. Basilar membrane & tectorial membrane=play crucial roles in activating the hair cells.v. Cilia=thin processes that protrude from the tops of the hair cells, which bend in response to pressure changes. vi. Two types of hair cells=inner & outer, located in diff places on the organ of Corti. vii.7. Be able to label the major structures of the cochlea (oval window, round window, scala vestibuli, scala tympani, basilar membrane, organ of corti, inner and outer hair cells, tectorial membrane). State the main principles of Bekesy’s place theory and discuss supporting evidence for the theory. a. Place theory of hearing=states that frequency of a sound is indicated by the place along the cochlea at which nerve firing is highest. Each place on basilar membrane is tuned to respond best to a different frequency. Base is tuned to high frequencies, apex is tuned to low frequencies, & best frequency varies continuously along the basilar membrane btwn these extremes. b. Evidence=confirmed by measuring the electrical response at different places along the