According to Official Guinness Records,
The most people fitted with hearing aids in 8 hours is 4,840, and was achieved by Starkey Hearing Foundation India (India) in Pune, Maharashtra, India, on 26 October 2018.The hearing aids were distributed to participants from the age of 5 to 85 without any charges.
For a complete list of 2018 records, please visit 2018 Guinness Records in India.