Completar Frases SoundVersión en línea Sound wave por Ayuni Amat 1 energy molecules compressions transferring longitudinal energy molecules lower air rarefactions further vibrates vibration vibrate longitudinal apart sound air molecules vibrate vibrates parallel higher closer other compressions rarefactions A longitudinal wave is a wave which travels in a direction to the direction of vibrations . An example of a longitudinal wave is . This is an example of how sound is produced from a loudspeaker : The loudspeaker , making air molecules surrounding it and therefore transferring vibration and to other molecules . This will produce a wave which is made up of series of and . Here is another example of how sound is produced from a guitar : The guitar's string , making surrounding it and therefore and to . This will produce a wave which is made up of series of and . Compression is a region where air molecules are together and they have pressure . Rarefaction , on the other hand , is a region where are and they have pressure .