Bronchiolitis is an infectious disease, with no effective treatment. Music and Mozart's works specifically, has been shown to have a positive effect on physiological parameters, while environmental noise is considered to be harmful. We aimed to evaluate the short-time effect of listening to music and detachment from environmental noise on the severity of bronchiolitis in hospitalized children.

MP3 player devices were uploaded with 3 different pieces: 1) sonata for 2 pianos in D major, K.488 by Mozart (2) instrumental music ("To the Point", by Dean Evenson & Tom Barabas) and (3) silence. All music or silence pieces were identical in length (24 minutes in accordance to the duration of the sonata).

Music fragments were played using headphones suitable and approved for use in children - GSI (Grason-Standler) Insert Earphone TIP-50 (50 ohm) (Grason Standler Inc. Madison, WI, USA). Sound frequency and volume were adjusted to the age appropriate values33 Children were randomly divided into 3 groups according to the type of intervention. Randomization, numbering of the MP3 players and coding of the content were done by a research coordinator not involved in evaluation of the patients nor in analysis of the results.

Inclusion Criteria:

• Patients aged 0-24 months, with the clinical diagnosis of bronchiolitis.

Exclusion Criteria:

• Children who failed neonatal hearing screening or in whom the results of the screening were not available were excluded from the study.
• Children who were not able to maintain listening for at least 10 minutes were excluded from data analysis