Pronunciation: [dˌiːˌɛnˈɛl] (IPA) 
The spelling of the word "DNL" is quite easy to understand when looking at its phonetic transcription using the International Phonetic Alphabet (IPA). The word is spelled as "dee-en-el" /diː.en.ɛl/. The first syllable "dee" is pronounced as the letter "D", followed by "en" which sounds like the letter "N". The last syllable "el" is pronounced as "L". Thus, the spelling of "DNL" corresponds to its IPA transcription /diː.en.ɛl/.
DNL is an acronym that stands for Day-Night Level. It is a term commonly used in acoustics and environmental noise assessment to represent a metric that measures the long-term average sound level, integrating both daytime and nighttime noise measurements. DNL is often used in the context of aircraft noise studies, particularly in relation to the evaluation of noise exposure around airports.
DNL is expressed in decibels (dB) and is calculated by summing the noise levels measured during a 24-hour period, considering certain adjustments to account for the increased sensitivity of human hearing during nighttime hours. Specifically, DNL takes into account a 10-decibel penalty for nighttime noise exposure, reflecting the fact that individuals generally have a lower tolerance for noise disturbance during sleep.
The DNL metric allows for the comparison and assessment of noise exposure over a significant period, providing an indication of the overall impact of noise on a given area. It is often used in urban planning, regulatory decision-making, and environmental impact assessments to evaluate whether noise levels are within acceptable limits and to assess potential impacts on human health and well-being.
In conclusion, DNL is a quantitative measure that combines daytime and nighttime noise levels to assess long-term noise exposure. Its use provides insight into the overall noise impact on a specific area, aiding in decision-making and the development of noise mitigation strategies.
