Pitch Perception
Music & Science Tutorial
2nd Essay question:
‘It might be tempting to assume that the pitch of a complex harmonic tone is simply determined by this lowest frequency component. However, the phenomenon of the ‘missing fundamental’ indicates that this is not the case.’ (STAINSBY) Give an account of the processes involved in the perception of pitch, with specific reference to the missing fundamental.
Introduction In order to perceive the pitch of a sound, the mechanical energy of the sound waves must be transformed into the electrical energy of nerve impulses. The auditory system is able to process the sound waves travelling through the air and carry out this transformation of energy which leads to the perception of a pitch. When a pitch is heard, it is the frequency of the sound (or the number of times per second the waveform repeats itself) which is being coded in the auditory system and then perceived as a pitch in the brain – although pitch is closely related to frequency, pitch is an auditory sensation of frequency and thus the two are not interchangeable. Research into how the auditory system is able to encode frequency information entering the ear suggests possible mechanisms taking place on the basilar membrane of the inner ear. Interestingly, studies also show how the brain is able to perceive a pitch when its corresponding frequency is not present in the sound entering the ear. This phenomenon is called the ‘missing fundamental’, as mentioned in the quote from Stainsby. The ‘missing fundamental’ has lead to further theories aiming to explain how frequency information is encoded in the auditory system and how analysis of this information can lead to the perception of a single pitch.
The Processes of Hearing The process of hearing a pitch begins when the sound is collected by the pinna of the outer ear. The pinna acts to channel the sound waves into the ear canal and the reflections of the sound waves off the pinna help to locate the source
2nd Essay question:
‘It might be tempting to assume that the pitch of a complex harmonic tone is simply determined by this lowest frequency component. However, the phenomenon of the ‘missing fundamental’ indicates that this is not the case.’ (STAINSBY) Give an account of the processes involved in the perception of pitch, with specific reference to the missing fundamental.
Introduction In order to perceive the pitch of a sound, the mechanical energy of the sound waves must be transformed into the electrical energy of nerve impulses. The auditory system is able to process the sound waves travelling through the air and carry out this transformation of energy which leads to the perception of a pitch. When a pitch is heard, it is the frequency of the sound (or the number of times per second the waveform repeats itself) which is being coded in the auditory system and then perceived as a pitch in the brain – although pitch is closely related to frequency, pitch is an auditory sensation of frequency and thus the two are not interchangeable. Research into how the auditory system is able to encode frequency information entering the ear suggests possible mechanisms taking place on the basilar membrane of the inner ear. Interestingly, studies also show how the brain is able to perceive a pitch when its corresponding frequency is not present in the sound entering the ear. This phenomenon is called the ‘missing fundamental’, as mentioned in the quote from Stainsby. The ‘missing fundamental’ has lead to further theories aiming to explain how frequency information is encoded in the auditory system and how analysis of this information can lead to the perception of a single pitch.
The Processes of Hearing The process of hearing a pitch begins when the sound is collected by the pinna of the outer ear. The pinna acts to channel the sound waves into the ear canal and the reflections of the sound waves off the pinna help to locate the source
References: Campbell M. and Greated, C. (1987), The Musician’s Guide to Acoustics, 39 - 62 Moore B. (1982), An Introduction to the Psychology of Hearing, 115 - 149 ----------------------- Fig. 1 [pic] [pic] Fig. 2 (Cross – Lecture 6, 12/11/10) (Cross – Lecture 6, 12/11/10) process produce neural firings which outline periods corresponding to the output waveforms. Each temporal pattern is analysed by a device which measures the time intervals between successive firings. Common time intervals are then found between the neural firings across the range of ‘channels’ and the most prominent time interval equals the period of the fundamental component. Thus, the perceived pitch corresponds to the reciprocal of the period of the fundamental component (Moore 1982).