Auditory imagery

Auditory imagery is a form of mental imagery that is used to organize and analyze sounds when there is no external auditory stimulus present. This form of imagery is broken up into a couple of auditory modalities such as verbal imagery or musical imagery. This modality of mental imagery differs from other sensory images such as motor imagery or visual imagery. The vividness and detail of auditory imagery can vary from person-to-person depending on their background and condition of their brain. Through all of the research developed to understand auditory imagery behavioral neuroscientists have found that the auditory images developed in subjects' minds are generated in real time and consist of fairly precise information about quantifiable auditory properties as well as melodic and harmonic relationships. These studies have been able to recently gain confirmation and recognition due to the arrival of Positron emission tomography and fMRI scans that can confirm a physiological and psychological correlation. Auditory imagery is a form of mental imagery that is used to organize and analyze sounds when there is no external auditory stimulus present. This form of imagery is broken up into a couple of auditory modalities such as verbal imagery or musical imagery. This modality of mental imagery differs from other sensory images such as motor imagery or visual imagery. The vividness and detail of auditory imagery can vary from person-to-person depending on their background and condition of their brain. Through all of the research developed to understand auditory imagery behavioral neuroscientists have found that the auditory images developed in subjects' minds are generated in real time and consist of fairly precise information about quantifiable auditory properties as well as melodic and harmonic relationships. These studies have been able to recently gain confirmation and recognition due to the arrival of Positron emission tomography and fMRI scans that can confirm a physiological and psychological correlation. The accuracy of tempo within an auditory image usually suffers when recalled however the consistency of a person’s perception of tempo is preserved. When surveying subject’s auditory imagery that their sense of tempo usually stays within 8% of the original tempo heard in a song that the subject heard at some point in the past. This was shown by having subjects compare the pitch of two words in a song. For instance, people can sing through “Jingle Bells” in their head and determine if there is a difference in pitch between the word ‘Snow’ and ‘Sleigh’. Experiments like this have shown it takes longer to compare the pitches of two words if the space between the two words is larger. Therefore the tempo structure of the melody is preserved in the auditory image. However, if someone had musical training then the person has more flexibility in his or her auditory imagery tempo representations. Humans retain a relatively strong auditory image for details in pitch, which can be improved with musical training. The development of cultivating an auditory image with absolute pitch, which is being able to determine a note upon hearing a sound, however, is dependent on childhood musical training and genetic factors. People are able to improve their discrimination of pitch; however, they cannot improve their detection. Auditory image pitch detection studies have shown that response time decreases when judging two high pitches as opposed to judging two low pitches. Of the many aspects of sound, loudness is a characteristic of auditory imagery that is usually lost or impaired. This is evident when people attempt to image a song and there is little noticeable volume dynamics in the auditory image. According to Pitt and Crowder, the encoding of loudness into our auditory imagery was shown to have little correlation with any physiological neural factors. Other scientists such as Intons-Petersons believe that there is encoding for loudness in our auditory images that if so it most likely occurs in a person’s motor cortex. The auditory imagery developed from lyrics or words generally is also considered a part of inner speech. When people image their voice or the voices of others it is considered inner speech but some researchers argue that it is a lack of self-monitoring of speech. This generally refers to imagining speech which can occur when trying to remember what someone said or the sound of their voice which can be elicited voluntarily or involuntarily. Auditory verbal imagery is considered useful for practicing and organizing things people would like to say in person. For instance, practicing a speech or getting ready to sing a part in a song. Cognitive scientists are very interested in finding out what brain structures are involved with mental imaging in order to provide consistent, localized, and more tangible evidence. It has been established that auditory imagery makes use of the right lobe since people with right lobe lesions tend to have difficulty generating auditory images. This is because auditory imaging requires the usage of the frontal and superior temporal right lobe as well as a lot of the right auditory association cortices. These portions of the brain are usually involved with interpreting the inflections of sounds (such as sad or angry sounds). The supplementary motor area is also involved in image generation and encodes motor processes to do, while the right thalamus is hypothesized to be a part of auditory image retrieval. The activation of the supplementary motor area is also relevant since it is a portion of the brain that is involved when a motor task is imagined as opposed to overly executed. This shows that developing an auditory image is partially a motor task. During auditory verbal imagery, the inferior frontal cortex and the insula were activated as well as the supplementary motor area, left superior temporal/inferior parietal region, the right posterior cerebellar cortex, the left precentral, and superior temporal gyri. Other areas of the brain have been activated during auditory imagery however there hasn’t been an encoding process attributed to it yet such as frontopolar areas, and the subcallosal gyrus. As associations between pieces of sound such as music or repetitive dialogue become stronger and more complex even the silence involved in the sound can initiate auditory images in the brain. Studies have been done in which people listen to a CD over and over with silence in between tracks and the neural activity was analyzed using fMRI. It was consistently found the prefrontal cortex and premotor cortical areas were active during the anticipation of auditory imagery. The caudal PFC was used a lot during the early stages of learning of the song while in later stages the rostral PFC was used more indicating a shift in the cortex regions used during auditory imaging association.