Audio filtration Notch filtering, an audio filtration technique, is proposed to reduce the vuvuzela sound in broadcasts and increase clarity of commentary audio. The vuvuzela produces notes at a frequency of approximately 235 Hz and its first partial at 465 Hz. However, this filtration technique affects the clarity of commentary audio. Proposals of adaptive filters by universities and research organisations address this issue by preserving the amplitude and clarity of the commentators' voices and crowd noise. Such filtration techniques have been adopted by some cable television providers. 2018 FIFA World Cup Vuvuzelas made a comeback at the 2018 FIFA World Cup in Russia, used mainly by Iranian supporters. Much like in 2010, there was a backlash against their use. Health effects and regulation Health concerns A study conducted in 2010 by Dr Ruth McNerney of the London School of Hygiene & Tropical Medicine and colleagues, concluded that the airborne transmission of diseases by means of vuvuzelas was possible. They measured tiny droplets emitted from a vuvuzela that can carry flu and cold germs that are small enough to stay suspended in the air for hours, and can enter into the airways of a person's lungs. The study concluded that vuvuzelas can infect others on a greater scale than coughing or shouting. The vuvuzelas have the potential to cause noise-induced hearing loss. Prof James Hall III, Dr Dirk Koekemoer, De Wet Swanepoel and colleagues at the University of Pretoria found that vuvuzelas can have a negative effect when a listener's eardrums are exposed to the instrument's high-intensity sound. The vuvuzelas produce an average sound pressure of 113 dB(A) at from the device opening. The study finds that subjects should not be exposed to more than 15 minutes per day at an intensity of 100 dB(A). The study assumes that if a single vuvuzela emits a sound that is dangerously loud to subjects within a radius, and numerous vuvuzelas are typically blown together for the duration of a match, it may put spectators at a significant risk of hearing loss. Hearing loss experts at the U.S. National Institute for Occupational Safety and Health (NIOSH) recommend that exposure at the 113 dB(A) level not exceed 45 seconds per day. A newer model has a modified mouthpiece that reduces the volume by 20 dB. Noise levels and bans Concerns about the constant intensities produced by the vuvuzelas during the 2010 FIFA World Cup matches