Vocalization and Imitation in Learning Sound Recognition

Hypothesis: vocalizing to imitate heart sounds and murmurs can improve their recognition

It is generally recognized that human learning is facilitated by imitation. At any age, imitation of actions, sounds and visual objects is important in learning the recognition and reproduction of what is perceived¹. Among vertebrates, some like dogs are auditory learners and can recognize sounds, as judged from their behaviour. Others such as songbirds, seals, bats, whales and humans can imitate perceived sounds and are vocal learners. Studies of songbirds have revealed the importance of imitation of sounds created by a bird tutor, in the learning of songs by young birds². It is evident that young birds must mimic the sounds they hear from a parent in order to develop appropriate songs themselves. In order to accurately mimic sounds they must also hear their own attempts and compare these with what they have heard from the parent. This comparison is possible due to neural connections between the aural input from the ear and motor control centre for the larynx, and possibly to “mirror neurons” which activate when actions are both performed and heard1. Experimental corruption of auditory neural signals leads to corruption of the sounds created by the birds.
In humans, normal hearing is important for accurate speech acquisition. Further, imitation facilitates learning of both speech and song. Functional Magnetic Resonance Imaging studies show activation of auditory and motor areas of the brain during vocalization, consistent with activation of auditory feedback influencing the sounds produced1. Musical training in many cultures involves extensive imitation which has been shown to enhance voice and instrumental learning³.

Thus, evidence in several species supports the crucial role of imitation in accurate speech and song production. Since this is apparently dependent on the comparison of vocalized sound and external sounds, it is reasonable to suggest that part of this process is enhanced recognition of the perceived sounds. This suggests that vocalization may enhance not just the mimicry but also the recognition of certain sounds.

Relation to heart auscultation

The teaching of heart sound and murmur recognition typically involves listening to live, recorded or synthesized sounds in order to provide examples of sounds for later recognition by students. Many teachers are adept in vocally mimicking heart sounds and murmurs which can give emphasis to their teaching. I suggest that a further step in the use of this mimicry is to encourage students to mimic heart sounds themselves. There are several reasons for this suggestion.

First, as noted above, vocalization may enhance more accurate recognition of what students are hearing. Second, the act of producing sounds engages muscle groups and motor areas in the brain as well as the auditory areas. There is some evidence from investigation of music recognition that with more areas of the brain activated, memory is enhanced^4,5.

Third, with vocalization I argue that learning becomes a more active process than the passive learning of simply listening, and active learning tends to be more effective than passive. Some instrumental music educators use vocalization of instrument sounds to enhance the learning of tone production⁵.

Assessing the effect of vocalization on heart sound and murmur recognition is problematic since it is such a simple intervention that a controlled investigation would be difficult. However, given the minimal time required, the ease of introducing it into presentations and the apparent lack of adverse consequences, I am using the technique in all medical student auscultation teaching. It is well received and often adds some humour to the teaching.