Levitin effect

Levitin's original study consisted of 46 volunteer students from Stanford University who were asked to participate in the study. Upon arriving at the study, the students filled out a background questionnaire and were then asked to select two songs from 56 previously chosen CDs. After the students choose their songs, they were asked to sing a part of their songs. The results of the study showed that 40% of the participants were able to sing a correct pitch in at least one of their songs, 12% were able to hit the correct pitch on both trials, and 44% were able to hit the pitch within two semitones.[1] The secondary study performed in 2012 was completed in 6 European Labs. This study was a competitive replication of Levitin's original study. The results of this study showed that 25% of participants were able to sing the correct pitch in at least one of their songs, 4% sang the correct pitches in both songs.[6] These studies show that people are generally able to remember songs similar to how they heard them, even with no reference music. When compared to Levitin's original study, the replication showed a lower trend of data, meaning that a smaller percentage of the population was able to recall the relative pitch. More data is needed to get a better understanding of how much of the population is able to accurately recall the relative pitch of a selected song.

Levitin offers possible explanations for this phenomenon, by describing how even young children have this ability to a certain degree, so this ability to recognize musical patterns could be located in the cerebellum the brain.[7] The cerebellum helps to control balance and coordination, but when listening to music the cerebellum helps the body interpret rhythm. Researchers at Lawrence Parsons and Peter Fox of University of Texas Health Science Center ran brain scans on conductors and saw an increase of blood flow to the cerebellum when they were following along to sheet music and listening to it at the same time. The scans showed that as the rhythm changed, the amount of blood flow in the cerebellum changed as well.[8] There are few theories that try and explain this occurrence. One theory states our ancestors needed to synchronize their steps in nature to avoid making more noise than necessary while hunting. Another theory suggests that those early humans who were able to distinguish rudimentary rhythms may have been able to hear and interpret different footsteps making them more attune to the environment around them and have better survival instincts.[9] Those who distinguish different sounds in the environment were more likely to survive and pass along their genetics. These are just possible theories as to how humans have developed pitch and rhythmic interpretation. There is no distinct evidence proving or disproving these theories.

Absolute pitch, also referred to as perfect pitch, is the ability to correctly identify or recreate a sound or pitch without needing a reference. This ability is rare among people but there has been shown to be a correlation between those who were exposed to music while they were babies and those who possess this ability. There is also evidence that this can be genetic. Meaning those who have a family member with absolute pitch are more likely to have it as well.[10] This skill is considered to be helpful to musicians, but many very successful musicians only rely on relative pitch. Relative pitch is more common in the population and is not believed to be based on any musical training or exposure. People's accuracy with determining relative pitch is what Levitin tries to show in his experiments. Relative pitch is people's ability to identify if the pitch of a note increases or decreases, as well as relative timbre of the music.[11]  Timbre is the overall tone or sound of the music, like if a person describes a song as happy, sad, warm, or cold. While many people in the population have some general understand of pitch it is not a necessary ability. There are people who cannot distinguish between pitches who lead a normal life. People who cannot distinguish between pitches can be born with this lack of ability or can develop it in their lives.

There are certain disorders in the brain that can prevent someone from having the ability to perceive relative pitch. These disorders can be congenital or developed. Amusia is a term used to describe someone who has difficulty differentiating pitch or identifying music. Congenital amusia is often referred to as being tone-deaf. Those with congenital amusia can process speech, differences in people's voices and hear environmental sounds, but most cannot identify patterns in music.[12] They describe it as not being able to "hear" music, it sounds like somebody banging different pots and pans, rather than a rhythmic melody. The level of Amusia can differ too. Some people can distinguish different songs and "hear" the music, while others have absolutely no understanding of music. Amusia can also be developed through traumatic brain injuries or lesions and tumours on the brain. Those who once could perceive relative pitch can lose this ability through an event like a head injury in a car crash. Sometimes this condition is reversible but there is not a way to know if the person will get be able to distinguish pitches again. Brain lesions or tumours can also have the same effect on people that causes them to develop amusia.[13] This reason for this condition is not exactly known, but research and brain scans indicate that part of the cause may be located in the frontal cortex of the brain.[14]