The phenomenon you are describing is known as the "Lombard effect" or the "Lombard reflex." It is a natural and involuntary response that occurs when an individual is in a relatively quiet environment and starts speaking or making noise. In this situation, the person's vocal volume and intensity tend to increase, seemingly amplifying their own voice.
The Lombard effect is named after Étienne Lombard, a French otolaryngologist who first described it in 1911. It is commonly observed in various species, including humans, as a means to adapt communication to noisy environments.
The main characteristics of the Lombard effect are as follows:
Increased vocal volume: When individuals find themselves in a noisy environment, they instinctively raise the volume of their speech to ensure that they are heard by others.
Pitch changes: In addition to increased volume, the Lombard effect can also lead to changes in pitch. People may speak at a higher pitch in noisy surroundings to enhance the audibility of their speech.
Persistence: As you mentioned, the Lombard effect can persist even after the noisy situation has passed. Once individuals become accustomed to speaking louder, they may continue doing so for some time until they consciously adjust their vocal volume back to a more normal level.
The Lombard effect is considered an adaptive response to noisy environments, as it helps maintain effective communication and ensures that speech remains audible amidst background noise. It is not a conscious decision; rather, it is an automatic mechanism that takes place in the brainstem and is related to auditory feedback and neural pathways involved in vocalization.
In addition to its role in speech communication, the Lombard effect has also been studied in the context of singing and musical performances, where performers may unconsciously adjust their vocal intensity in response to changes in ambient noise levels.